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Old 12-10-2008 - Glossary and Definitions - Networking Computer Systems - Computer Networking Systems - Genaral - Voltage Talk forum
Brigette Power
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Default Glossary and Definitions - Networking Computer Systems

ablative The development of a hard char that resists the erosion of fire and flames; a characteristic of a firestop when exposed to fire.
above finished floor (AFF) Standard mounting height or vertical distance (e.g., 1220 mm [48 in] AFF) for a fixture, ceiling, device, or any other object measured from the finished floor surface to the center line of the object as the measurement point.
absolute filter A filter capable of collecting solid particles greater than a stated micron size.
absorption 1. A phenomenon causing attenuation of radio signals passing through a medium. It occurs when gaseous molecules or suspended water particles in the atmosphere absorb the signal energy and convert it into heat due to molecular resonance. 2. In the transmission of electrical, electromagnetic, or acoustic signals, the conversion of transmitted energy into another form, usually thermal. Absorption is one cause of signal
accelerator A chemical agent used to hasten a chemical reaction for setting permanent bonds on epoxy glues.
acceptance plan A facilitating agreement between parties (e.g., contractor and client or client representative) that defines satisfactory completion of a project task or complete project. It may include items on which the client’s acceptance is dependent (e.g., delivery of as-built drawings, test certification).
acceptance test A test or set of tests performed to demonstrate satisfactory completion of a predetermined task or group of tasks on which acceptance is dependent.
access control mechanism The way devices on a LAN are granted or denied access to the network.
access floor A system consisting of completely removable and interchangeable floor panels that are supported on adjustable pedestals or stringers (or both) to allow entry to the area beneath.
access point (AP) 1. The point of entry into a secure area. 2. A stand-alone hardware device or a computer wireless adaptor with software that acts as a wireless communication hub for users of wireless devices to connect with each other and to bridge those devices to the cabled portion of the network.
access provider (AP) 1. A company (e.g., telephone company) that provides a circuit path between a service provider (SP) and the client user. An AP also can be the SP. 2. The operator of any facility that is used to convey telecommunications signals to and from a customer premises. See also service provider (SP).
acrylate A coating applied during the optical fiber manufacturing process to provide physical and environmental protection for the optical fiber.
active circuit Any circuit connected to an energized system.
active equipment Energized equipment used for receiving or transmitting analog or digital signals (e.g., switches, hubs, routers, private branch exchanges).
adapter A device that enables any or all of the following: • Different sizes or types of plugs to mate with one another or to fit into a telecommunications outlet. • Rearrangement of leads. • Large cables with numerous wires to fan out into smaller groups of wires. • Interconnection between cables. (TIA)
adapter; optical fiber duplex A mechanical device designed to align and join two duplex optical fiber connectors (plugs) to form an optical duplex connection. (TIA)
addendum A document used to provide additional requirements and recommendations to a published document (e.g., standards, contracts). When published, an addendum effectively becomes part of the document that it supports.
address 1. A unique identification code assigned to a network device, used to associate a message with its source and destination. See device address, medium access control (MAC) address, and network address. 2. A unique location in a computer’s memory or other electronic storage medium. See medium access control (MAC) and network address.
address resolution A process used to associate network addresses with media access control addresses.
adjacent channel discrimination A measure of the ability of a receiver to successfully receive a signal in a wanted frequency channel in the presence of unwanted signals on adjacent frequency channels, which are being picked up by the antenna.
administration 1. The methodology defining the documentation requirements of a cabling system and its containment, the labeling of functional elements, and the process by which moves, additions, and changes are recorded. (ISO) See also cable labeling system. 2. See network administration.
aerial-buried plant A general term for all outside plant cable runs made up of both aerial and direct-buried cables.
aerial cable Telecommunications cable installed on aerial supporting structures (e.g., poles, sides of buildings, other structures). (TIA)
aerial entrance An entrance facility where the cables providing service to a building are placed overhead and the entry point is located above the ground level.
aerial plant An overhead infrastructure to provide telecommunications services between facilities.
afterset insert See insert, afterset.
air bottle Portable compressed air or gas source.
air handling unit (AHU) The AHU monitors and controls the air by volume, temperature, and humidity before being released into a specified building area. Typically, an AHU consists of a fan, hot and/or cold coils, and supply/return ducts and dampers. The AHU mixes indoor/outdoor air and passes the mixture of air through the coils.
air terminal A strike termination device that is a point receptor for attachment of flashes to the lightning protection system and is listed for the purpose. Typical air terminals are formed of a tube or solid rod. Also called a lightning rod.
alarm indicator A device or a combination of devices (e.g., a bell, lamp, strobe, horn, gong, or buzzer) that responds to a signal from an alarm sensor and indicates a fault or emergency condition.
alien crosstalk Unwanted coupling of signals into a balanced twisted-pair in a given cable from one or more balanced twisted-pair(s) external to the given cable.
alternate entrance A supplementary entrance facility into a building using a different routing to provide diversity of service and for assurance of service continuity. (TIA)
alternate route A secondary communications path used to reach a destination. See diverse route.
alternating current (ac) 1. Current flow that alternates periodically (usually sinusoidal) in magnitude and direction. 2. The letters ac are used generically to refer to any periodically alternating (e.g., a sinusoid) waveform or signal (e.g., a line voltage of 115 Vac). Contrast with direct current.
alternating current equipment ground (ACEG) A conductor installed from the equipment grounding busbar inside an electrical panel to a telecommunications grounding busbar or telecommunications main grounding busbar.
American Institute of Architects (AIA) An organization that provides resources, continuing education, and networking for architects.
American National Standards Institute (ANSI) A private, nonprofit membership organization focused on meeting the standards and conformity assessment requirements of its diverse constituency. It provides a neutral forum for the development of consensus agreements on issues relevant to voluntary standardization. The United States (U.S.) representative to the International Organization for Standardization, and through the U.S. National Committee, to the International Electrotechnical Commission.
American Society of Heating, Refrigerating, and Air-Conditioning Engineers (ASHRAE) An international society organized for the sole purpose of advancing the arts and sciences of heating, ventilating, air conditioning, and refrigerating for the public’s benefit through research, standards writing, continuing education, and publications.
American wire gauge (AWG) A system used to specify wire size. The greater the wire diameter, the smaller the AWG value. Historically, the AWG number has represented the number of drawing processes applied to a given wire.
Americans with Disabilities Act (ADA) United States Department of Justice regulations and guidelines under civil rights law that ensure individuals with disabilities have access to, or may use, public entities and government buildings.
ampacity The current, in amperes, that a conductor can carry continuously under the conditions of use without exceeding its temperature rating. (NEC®)
ampere (A, amp) A unit of measurement of electric current. One ampere is equal to the current produced by one volt flowing through a resistance of one ohm.
amplifier A device that increases the power level (amplitude) of an analog signal (waveform). Amplifiers boost the power in its assigned frequency range, including the intended signal and any induced noise.
amplitude The maximum absolute value reached by a voltage or current waveform.
amplitude modulation (AM) Modulation in which the amplitude of a carrier wave is varied in accordance with some characteristic of the modulating signal.
analog input (AI) A device (e.g., a temperature sensor) that sends a continuously variable signal to a building automation system controller.
analog output (AO) A device (e.g., a damper actuator) that receives a continuously variable signal from a building automation system controller.
analog signal A continuous function of time. Contrast with digital signal.
anchor 1. A fastening device. 2. In an outside plant environment, a device made up of a single plate or series of flat plates, and combined with a rod having a connecting eye.
annular space A space between a penetrating item and the inside wall of penetration.
annunciator A unit containing one or more indicator lamps, alphanumeric displays, or other equivalent means in which each indication provides status information about a circuit, condition, or location.
ANSI/TIA/EIA Associations involved in developing telecommunications industry standards.
antenna A conductive structure specifically designed to couple or radiate electromagnetic energy. In radio frequency systems, the antenna may be used to both transmit and receive electromagnetic energy.
apparatus closet See telecommunications room.
application address An address used to uniquely identify each software process running on a network device. See medium access control address and network address.
application specific cabling Cabling installed to meet the requirements of a specific transmission system or application.
application software Software used to perform a specific task (e.g., word processing, spreadsheet analysis, or database management).
approved Official consent typically denoted by an authority having jurisdiction.
approved floor ground See approved ground, earth ground, and ground.
approved ground A grounding (earthing) source approved for use by the authority having jurisdiction. See also earth ground and ground.
aramid A material with exceptional tensile strength and coefficient of thermal expansion near that of glass. Widely used as a strength member in optical fiber cables. See aramid yarn.
aramid yarn A strength element used in cable to provide support and additional protection of the fiber bundles. See also aramid.
arbitration 1. A method of negotiation used in resolving disputes between parties. 2. The process of determining which requesting device will gain access to a resource. (IEEE)
architectural assemblies Walls, partitions, or other barriers that are not load bearing. (TIA)
architectural drawing A two-dimensional graphical representation of a building, space, or object prepared with adequate detail to convey design information in a manner to serve as a guide for construction thereof.
architectural structures Walls, floors, floor/ceilings, and roof/ceilings that are load bearing. (TIA)
archive Collection and storage of data, records, or information.
armoring Method used for protecting cables against crush, impact, rodents, etc. Can be achieved through the use of corrugated steel, fiber-reinforced polymer rods, steel wire, glass yarns, or other suitable materials under or over the outer sheath of the cable.
asbestos Fibrous mineral substance used in buildings as insulation between the mid-1940s and 1978 and later found to be carcinogenic (cancer causing).
as-built The documentation of measurements, location, and quantities of material work performed. May be in the form of marked up documents or other work order forms.
as-built drawing See record drawing.
asymmetric digital subscriber line (ADSL) A digital service designed to provide high data transfer rates over traditional telephone cable. Asymmetric refers to different speeds for uplink and downlink traffic. See also digital subscriber line (xDSL).
asymmetric full-duplex A transmission process that allows different sending and receiving transfer rates to coexist on the same path for Ethernet video-on-demand.
asynchronous communication See asynchronous signaling.
asynchronous signaling A form of signaling in which each data character is coded as a string of bits. The bits are separated by start character and stop character bits. See also isochronous communication, synchronous communication, and synchronous transmission.
asynchronous transfer mode (ATM) A high-speed packet switching protocol that utilizes fixed-length (53-byte) packets, called cells, to carry all types of traffic (e.g., voice, data, still image, audio/video).
asynchronous transmission See asynchronous signaling.
attenuation The decrease in magnitude or the power loss of a signal that propagates between points, expressed in dB as the ratio of received signal to transmitted signal level. See also insertion loss.
attenuation-to-crosstalk ratio (ACR) The ratio obtained by subtracting insertion loss (attenuation [dB]) from near-end crosstalk (dB). ACR is normally stated at a given frequency. See also bit error rate (BER) and signal-to-noise ratio (SNR).
audit trail A sequential record that accounts for all the activities of an access control system. This record allows for the analysis of events over a given time period.
aught Colloquial term for numerical symbol “0” that is used in the numbering scheme for conductors larger than 0 AWG [8.3 mm (0.33 in)] (e.g., 2/0 AWG [13.41 mm (0.528 in)]) is two aught.
authority having jurisdiction (AHJ) The entities responsible for interpretation and enforcement of local building and electrical codes.
autotest A function used by field test instruments to run all the required tests in a sequential manner without operator intervention.
auxiliary disconnect outlet (ADO) 1. An extension of a demarcation point from a common owner’s space into a tenant’s individual space. 2. A device usually located within the tenant or living unit used to terminate the ADO or backbone cable. (TIA)
auxiliary disconnect outlet (ADO) cable 1. The cable that extends the demarcation point in a common owner’s space to a tenant’s individual space. 2. In individual applications, the cable from the auxiliary telecommunications disconnects outlet/connector or the distribution device in a customer’s premises to the backbone facility or the point of demarcation. (TIA)
average power (PA) Sustainable or usable portion of electrical energy in an alternating current over some amount of time. For sinusoidal signals, it is the peak power (PP) multiplied by .707 (e.g., 100 watts of PP is approximately equal to 71 watts of PA). See also power and peak power.

backboard A panel (e.g., wood, metal) used for mounting connecting hardware and equipment.
backbone 1. A facility (e.g., pathway, cable, conductors) between any of the following spaces: telecommunications rooms, telecommunications enclosures, common telecommunications rooms, floor-serving terminals, entrance facilities, equipment rooms, and common equipment rooms. (TIA) 2. In a data center, a facility (e.g., pathway, cable, conductors) between any of the following spaces: entrance rooms or spaces, main distribution areas, horizontal distribution areas, and telecommunications rooms.
backbone cable See backbone and backbone cabling.
backbone cabling Cable and connecting hardware that provide interconnections between telecommunications rooms, equipment rooms, and entrance facilities. See also backbone.
backbone loop diversity A type of loop diversity that assigns circuits among different intrabuilding backbone cables.
backbone networks An intermediate data network connecting two or more LANs. See internetwork.
backbone pathway The portion of the pathway system that permits the placing of main and high-volume cables between the entrance location and all cross-connect points within a building and between buildings.
backbone raceway See backbone pathway.
backscatter The scattering of light into a direction opposite to the original direction.
backscatter coefficient The ratio of backscattered light to transmitted light. The backscatter is a fixed percentage of the transmitted light.
backup path A secondary or alternate channel for signal flow. It is typically used when there has been a failure of the main (primary) path.
BACnet® broadcast management device (BBMD) A BBMD is one of the BACnet/IP broadcast management methods outlined in ISO 16484-5. This standard incorporates all amendments to ANSI/ASHRAE Standard 135 since 1995.
BACnet® interoperability building block (BIBB) The purpose of a BIBB is to simplify interoperability into common functions that are intuitive to specifiers and owners and then define a name and set of simple BACnet requirements for each.
BACnet® Testing Laboratories (BTL) The BACnet Manufacturer’s Association offers a product testing and listing program for building automation products that have BACnet capability. Laboratories that conduct such testing and listing services are known as the BACnet Testing Laboratories.
BACnet® virtual link layer (BVLL) A BACnet/IP communication is implemented by defining a new protocol layer called the BACnet virtual link layer. The BVLL provides the interface between the BACnet Network layer and the underlying capabilities of a particular communications subsystem.
badge reader See card reader.
balanced cable Two or more insulated pairs of wires—identical in composition, size, and length—uniformly twisted together.
balanced copper cable A cable consisting of one or more copper symmetrical cable elements (twisted-pairs or quads). See also balanced cable.
balun A balanced-to-unbalanced circuit-coupling device, used to convert from unbalanced to balanced transmission, and provides impedance matching for connecting twisted-pair to coaxial cabling.
bandwidth 1. A range of frequencies available for signaling expressed in hertz. 2. The information-handling capability of a medium, expressed in units of frequency (hertz).
barrel connector A female-to-female adaptor used to join two connectorized segments of coaxial cable together.
barrier A partition installed in a raceway or cable tray that provides complete separation from the adjacent compartment.
barrier (architectural) Architectural structures or assemblies. (TIA)
baseband service A method of communication in which all of the bandwidth is dedicated to a single communications channel allowing only one single message transfer to occur at a time.
baseband signaling See baseband transmission.
baseband transmission A transmission technique in which all of the available bandwidth is dedicated to a single communications channel. Only a single message transfer can occur at a given time.
baseboard pathway A distribution method in which channels containing cables run along or within the baseboards of a building or modular furniture.
basic link test configuration Obsolete term. Refer to permanent link.
bearing plate A steel plate placed under one end of a beam, column, or truss at a support point for load distribution.
bearing wall A wall supporting a load other than its own weight. (TIA)
bel A logarithmic ratio of analog signal strengths; named in honor of telephone pioneer Alexander Graham Bell.
bend radius The radius of curvature that a media can bend without signal degradation.
bias tee A type of connection used to inject dc power to combine the ac radio frequency signal on one end of a coaxial cable, and tap it off at the other end, thereby allowing remote powered devices to operate without a separate local power source.
BICSI® An international telecommunications association offering training, conferences, publications, and registration programs for cabling distribution designers, as well as commercial and residential installers.
bid form A prepared document that the bidder will submit to the owner, or contracting agent.
bidders’ conference A meeting conducted by the issuer of a request for quote or request for proposal to review and address any questions from respondents (bidders) with regard to the bid documents.
bidding documents All construction documents issued to bidders before the signing of an owner-contractor agreement.
binary digit (bit) 1. The smallest unit of information in digital systems. 2. Zeros and ones used to represent data processed by digital devices.
biometrics An automated method of recognizing a person based on physiological or behavioral characteristics.
bit error rate (BER) 1. The ratio of incorrectly transmitted bits to total transmitted bits. A primary specification for all transmission systems, it is usually expressed as a power of 10. The number of errors made in a digital transmission as compared to complete accuracy. 2. The fraction of bits transmitted incorrectly. See attenuation-to-crosstalk ratio and signal-to-noise ratio.
bit per second (b/s) A unit of measure used to express the binary data transfer rate of a device, system, or communications channel. Also called bit rate.
bit stream A series of binary digits (zeros and ones) representing the message being transferred between devices.
blank cell The hollow space of a cellular metal or cellular concrete floor unit without factory installed fittings. (TIA)
blended floor system A combination of cellular floor units with raceway capability and other floor units with raceway capability, systematically arranged in a modular pattern. (TIA)
Bluetooth® A low-power radio frequency personal area network technology that enables cordless data transfer between Bluetooth-equipped devices at short range.
bond 1. An electrical connection using a low-resistance path. 2. A written obligation under seal to guarantee that specific documents are accurate or that the bonded party will meet specific requirements, in a specific way, within a specific time period.
bonding The permanent joining of metallic parts to form an electrically conductive path that will ensure electrical continuity and the capacity to conduct safely any current likely to be imposed. (TIA)
bonding conductor (BC) A conductor used specifically for the purpose of bonding.
bonding conductor for telecommunications (BCT) A conductor that interconnects the building’s service equipment (power) ground to the telecommunications grounding system.
boring A method to displace earth under the ground without breaking the ground surface (trenching) or cutting ground surfaces (e.g., sidewalks, driveways, parking lots, road surfaces). Normally, as dirt is displaced or removed, conduit is inserted.
break-out cable Multifiber cables where each optical fiber is further protected by an additional jacket and optional strength elements.
bridge A Layer 2 networking device used to connect separate LAN collision domains (or network segments) to extend network reach or selectively isolate network traffic.
bridged tap A connection that enables multiple appearances of the same cable pair at several distribution points. (TIA)
bridging (architectural) A system of bracing between floor beams to prevent lateral instability.
broadband transmission The transmission of multiple signals on a medium at the same time, sharing the entire bandwidth of the medium (e.g., video signals multiplexed into channels with a bandwidth of 6 MHz each).
browser Applications software used to access Web-based content.
buffer A temporary storage area in a networking device used to hold incoming data until it can be processed.
buffer coating A protective thermoplastic material that is applied to the acrylate layer of the optical fiber to protect against environmental hazards. May be more than one layer.
buffering The process of providing a supplemental air supply to pressurized cables during splicing operations.
buffer tube A supplemental loose-fitting cover, which is applied over the primary coated optical fibers at the time of installation.
building automation and control network (BACnet®) An industry standard protocol for building automation and control networks developed under the auspices of the American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE), published as ANSI ASHRAE standard 135-2004. BACnet defines a fourlayer
architecture that includes the Physical, Data Link, Network, and Application layers of the Open Systems Interconnection Reference Model (ISO 7498).
building automation system (BAS) Equipment and telecommunications infrastructure that supports monitoring, control, operation, and management of building services. (TIA)
building automation system outlet A connecting device between a horizontal cable and a coverage area device. (TIA)
building core A three-dimensional space, permeating one or more floors of the building and used for the extension and distribution of utility services (e.g., elevators, washrooms, stairwells, mechanical and electrical systems, and telecommunications) throughout the building. (TIA)
building distributor (BD) A distributor in which the building backbone cable(s) terminate(s) and at which connections to the campus backbone cable(s) may be made. International equivalent term for intermediate cross-connect.
building entrance The point where services media enter or leave the building. See also entrance room or space (telecommunications) and entrance facility (EF[telecommunications]).
building entrance terminal Cable termination equipment used to terminate outside plant cables at or near the point of building entry.
building module The standard selected as the dimensional coordination for the design of the building. The international standards have established a 101 mm (4 in) basic module. This produces modular coordination to all building materials, products, and utilization of the floor space.
building horizontal pathway See pathway.
building signaling system See building automation system.
bundle 1. Many individual optical fibers contained within a single jacket or buffer tube. Also, a group of buffered optical fibers distinguished in some fashion from another group in the same cable core. 2. Used to indicate time and common handling of multiple cables routed together.
bundled cable An assembly of two or more cables continuously bound together to form a single unit. (TIA) Contrast with hybrid cable.
buried cable A cable installed under the surface of the ground in such a manner that it cannot be removed without disturbing the soil. (TIA) See direct-buried cable and underground cable.
bursty A characteristic of digital transmission where the transmission rates have large variations during short periods of time.
bushing An insulating lining for an aperture through which multiple conductors may pass.
butt set See telephone test set.
butterfly detail A maintenance hole diagram showing all four walls and detailing route and splicing locations of cable passing through the maintenance hole.
byte A data unit made up of eight bits. Also called an octet.

cabinet A container that may enclose connection devices, terminations, apparatus, wiring, and equipment. (TIA)
cable An assembly of one or more insulated conductors or optical fibers, within an enveloping sheath. (TIA)
cable assembly A cable that has connectors installed on one or both ends. See jumper and pigtail.
cable labeling system 1. The scheme employed when identifying cable or its associated hardware. 2. Scheme adapted for labeling cables to identify them based on ANSI/TIA/EIA-606-A, Administration Standard for Commercial Telecommunications Infrastructure. See administration.
cable rack The vertical or horizontal open support structure (usually made of aluminum or steel) that is attached to a ceiling or wall.
cable reel A spool or bobbin for storing and distributing cable.
cable sheath A covering over the optical fiber or conductor assembly that may include one or more metallic members, strength members, or jackets. (TIA)
cable terminal An assembly used to access the conductors of a cable.
cable tray (CT) A rigid structure for housing and protecting cables or conductors. Usually consists of one-piece solid or ventilated bottom or individual transverse members with two side rails.
cabling A system of cables, cords, and connecting hardware.
calibration Task of verifying test equipment against a reference.
campus The buildings and grounds having legal contiguous interconnection. (TIA)
campus distributor (CD) The distributor from which the campus backbone cabling emanates. (ISO, CENELEC, AS/NZS) International equivalent term for main crossconnect.
capacitance 1. The ability of an electronic component to store electrical energy. 2. Opposition to a change in voltage.
capacitance unbalance A capacitance unbalance between conductors of two pairs (or between the conductors and the ground) that are located in close proximity to each other within a cable that can result in the undesirable transferring of signal that is commonly referred to as crosstalk.
capping 1. Applying a closure device to an insert after the floor fitting is removed. 2. Covering cables located within a wall chase. 3. Sealing the end of a cable to prevent moisture intrusion prior to termination.
carbon protector An overvoltage protector that uses closely spaced carbon electrodes (granules) for voltage limiting.
card reader A device that retrieves information stored on an access card or badge and transmits the information to a controller. Also called badge reader.
carrier A signal modulated by an information source, thereby making it carry the information. See also access provider (AP).
carrier sensing The monitoring of a communications channel to check if it is free before transmitting (i.e., to see if any network devices are transmitting).
category A rating that defines the performance of cabling components and systems. Describes mechanical properties and transmission characteristics of balanced twisted-pair cabling and provides a numbered designation. Categories are defined in many regional standards (e.g., ANSI/TIA/EIA, ISO, AS/NZS, JIS).
category 3 Balanced twisted-pair copper cable specifications characterized in a frequency range from 1 to 16 MHz.
category 4 The Telecommunications Industry Association no longer recognizes this category.
category 5 The Telecommunications Industry Association no longer recognizes this category. ISO/IEC 11801.E.0.2, Generic Cabling for Customer Premises, does recognize this category. It is the functional equivalent of TIA category 5e.
category 5e Balanced twisted-pair copper cable specifications characterized in a frequency range from 1 to 100 MHz. This category specified transmission parameters that were not characterized by category 5 (e.g., power sum near-end crosstalk, return loss, equal level far-end crosstalk, and power sum equal level far-end crosstalk) and
features more stringent near-end crosstalk than category 5.
category 6, augmented Balanced twisted-pair copper cable specifications characterized in a frequency range from 1 to 500 MHz. The augmentation from category 6 covers frequency range, insertion loss specifications, and alien crosstalk mitigation.
category 7 Balanced twisted-pair copper cable specifications characterized in a frequency range from 1 to 600 MHz.
catenary wire See support strand (messenger).
cavity wall A wall built of solid masonry units arranged to provide air space within the wall. (TIA)
CEBus® Industry Council (CIC) A multi-industry organization of companies, incorporated as a nonprofit corporation, to develop and enlarge the market for products compliant with the CEBus standard and/or the common application language as implemented in the home plug and play specification. The council maintains the value of its certification marks while facilitating interoperability among product and with multiple
transport protocols through the maintenance of the standard and specification, its application database, product testing, and conformance certification.
ceiling distribution system 1. A distribution system that utilizes the space between a suspended or false ceiling and the structural surface above. (TIA) 2. In open-ceiling areas, cables serving the work area outlets from above.
cell 1. A single raceway of a cellular or underfloor duct system. (TIA) 2. A 53-byte data transfer unit used by asynchronous transfer mode networks. 3. The fixed area in which a wireless base station is configured to operate. 4. A single wireless LAN access point and its associated clients.
cellular floor (CF) A floor distribution method in which cables pass through floor cells, constructed of steel or concrete to provide a ready-made raceway for distribution of power and telecommunications cables. (TIA)
cellular floor raceway An assembly of hollow, longitudinal units constituting part of a floor, and systematically placed for the distribution of cables. (TIA)
CE marking A Conformité Européene mark fixed to the product itself or its packaging, instructions for use, or guarantee certificate. It indicates that the product complies with all relevant European directives that call for its application (e.g., electromagnetic compatibility directive).
cementitious firestop A firestopping material that is mixed with water, similar in appearance to mortar. See also firestopping. (TIA)
CENELEC (Comité Européen de Normalisation Electrotechnique) European standards organization responsible for electrotechnical standardization in the field of information technology.
central member The center component of a cable installed as a strength element.
central office (CO) A common carrier switching center office (also called central office or public exchange) that is conveniently located in areas to serve subscriber homes and businesses.
central processing unit (CPU) That part of a computer in which logical operations are performed.
centralised optical fibre cabling Techniques that create a combined backbone/horizontal channel. The channel is provided from the work area to the centralised crossconnect or interconnects by allowing the use of pull-through cables or splices. (ISO)
certification test set A test set designed specifically to measure the properties of a circuit to determine whether the circuit meets certification standards.
change order A document issued after the construction agreement has been signed authorizing modifications of the work to be completed or an adjustment in the contract sum or time. (CSI)
channel 1. The end-to-end transmission path connecting interfaces of any two pieces of application-specific equipment. Equipment cords and work area cords are included in the channel. 2. In frequency division multiplexing, a band in the frequency spectrum that is assigned to a specific logical connection. 3. In time division multiplexing, a time that is assigned to a specific logical connection.
channel bank A multiplexing device that divides a high-speed digital service into multiple, smaller, fixed-size channels that can be separated accessed. The device also allows several channels to be linked into larger bundles (often referred to as Nx64).
chase nipple A metallic bushing used with a locknut, inserted into a hole (typically in a metal enclosure) to protect cabling from abrasion on sharp edges.
chemical electrode Copper tubes containing a chemical that slowly leaches into the soil, lowering the soil’s resistance. Also called a chemical ground rod.
chemical ground rod See chemical electrode.
circuit (ckt [U.S.], cct [European]) The electrical or optical path used for communications between two devices.
circuit switching A communications method in which a dedicated communications path is established between two devices prior to message transfer. Contrast with packet switching.
circular mil Measuring unit used to specify the cross-sectional area of conductors.
cladding The outer concentric glass layer that surrounds the optical fiber core and has a lower index of refraction than the core.
classified Suggests that a product or system has been organized into a class or category.
client A network device that requests services from a server.
client/server model A form of distributed computing in which a series of interdependent tasks are processed by two or more computers on a network, allowing client devices with limited processing capabilities to gain access to the available resources of one or more servers attached to the network.
client software Addition to a station’s operating system that enables access to network resources.
clock A signal used to synchronize communications between devices.
closed-circuit television (CCTV) A private television system, typically used for security purposes, in which the signal is transmitted to a limited number of receivers.
cluster A collection of servers and associated storage devices interconnected using a dedicated, high-speed network. The collection appears as a single device to the network. All incoming requests are divided among the servers for quicker response. See load balancing.
coating See buffer coating.
coax See coaxial cable.
coaxial cable A cable consisting of a central metallic inner conductor separated from an enclosing outer conductor by a dielectric material. This material may be solid, foam, a suitable gas, or dry air. The outer conductor comprises a metallic braid, a foil layer, combination of braid, and foil
code A rule intended to ensure safety during the installation and use of materials, components, fixtures, systems, premises, and related subjects. Codes are typically invoked and enforced through government regulation.
codec A device that can transform an analog signal into a digital bit stream (coder) and digital bit stream into an analog signal (decoder).
collapsed backbone An internetwork contained in one device. Individual networks are connected to this central device and can then communicate with one another.
collision An event on a network indicating that two or more devices have simultaneously accessed the communications channel.
collision detection The process initiated when two or more network devices on an Ethernet network attempt to send a message at the same time and their messages collide.
A device stops transmitting when it detects a collision and only attempts to retransmit after waiting a random period of time.
common element (CE) A portion of a dock that is publicly accessible to all marina users.
common-mode (CM) circuit The closed circuit for the common-mode or ground loop current.
common-mode (CM) noise (and longitudinal) See common-mode voltage and longitudinal noise.
common-mode (CM) voltage A symmetrical noise voltage that is coupled into a cabling channel or link with equal magnitudes and in phase from each conductor measured at the cable’s point relative to ground potential.
communications plenum (CMP) cable Type CMP communications plenum cable shall be listed as being suitable for use in ducts, plenums, and other spaces used for environmental air and shall also be listed as having adequate fire-resistant and low smokeproducing characteristics.
communications protocol See protocol.
communications riser (CMR) cable Type CMR communications riser cable shall be listed as being suitable for use in a vertical run in a shaft or from floor to floor and shall also be listed as having fire-resistant characteristics capable of preventing the carrying of fire from floor to floor. (NEC)
community antenna television (CATV) system A system of television reception in which signals from distant stations are picked up by a master antenna and sent by cable to the individual receivers.
compartmentation The segregation of components, programs, and information. Provides isolation and protection from compromise, contamination, or unauthorized access.
complementary code keying (CCK) A single carrier modulation technique used in IEEE 802.11b and IEEE 802.11g networks.
completion bond An obligation made binding by a money forfeit that ensures a contractor will finish a project to the specifications of its request for quote within a specified time.
composite conductor A conductor constructed from nontraditional materials (e.g., metallic resins or graphite).
concrete-encased electrode An electrode encased in concrete that is in direct contact with the earth.
concrete fill A minimal-depth concrete pour to encase single-level underfloor duct. (TIA)
conductance (G) The measure of the ease with which electrical current flows through a conductor. Uniformly distributed along the conductor length, conductance varies as a function of a conductor’s geometry and the dielectric properties of the materials surrounding the conductor. One of the primary transmission parameters for transmission lines is the opposite of resistance. The unit of measure is siemens (S).
conductor A media (e.g., solid, liquid, gas) for transmitting electric current, electromagnetic waves/light.
conduit 1. A raceway of circular cross-section. 2. A structure containing one or more ducts. (TIA)
conduit run Multiple sections of conduit that are joined together with fittings.
conduit stub-up A short section of conduit that is installed from a receptacle box, usually in a wall, into an accessible ceiling space directly above the receptacle box.
condulets A conduit coupling that has a removable side plate to allow access to the cable for pulling purposes.
cone of protection A cone-shaped space, the apex of which is the top of the conductor or lightning protective mast and with the base being a circle at the earth surface. See zone of protection.
confined space The work space defined by the Occupational Safety and Health Administration as one a worker can enter and work in but that has limited or restrictive means of entry or exit and that is not designed for continuous occupancy (e.g., maintenance holes, splice pits, crawl spaces, and attics).
congestion A state in which the volume of messages exceeds the designed capacity of a communications channel or network fabric, resulting in transfer delays or failures.
connecting hardware A device, or a combination of devices, used to connect cables or cable elements.
connector A mechanical device used to provide a means for aligning, attaching, and achieving continuity between conductors or optical fibers.
connector, small form factor An optical fiber duplex connector with a footprint approximating that of an 8-position outlet connector typically used with 4-pair copper connectors.
consistency check A method of verifying the confidence of a field measurement.
consolidation point (CP) A location for interconnection between horizontal cables extending from building pathways and horizontal cables extending into furniture pathways. (TIA)
construction document (CD) The written and graphic document prepared or assembled by the architect or engineer for communicating the design of the project.
construction management and manager An added participant in the process, employed by the owner to oversee and administer the project.
Construction Specifications Institute (CSI) Creates and maintains a construction specifications book that is used by the American Institute of Architects.
consultant A specialist who provides services to the design team that is headed by an architect or engineer who is under contract with the owner.
Consumer Electronics Bus (CEBus®) An open architecture set of specification documents that define protocols for making home products and appliances communicate.
containment 1. The process of dividing a structure into fire zones. Also called compartmentation. 2. A term used in the to describe cable raceway products (e.g., wall trunking, basket trunking, galvanised tray work).
contention A networks access method in which devices compete for use of the available communications channel.
contingency A sum of money, usually a percentage of the estimated construction cost, held in reserve to pay for unforeseen costs that may arise during a project.
contract Written document covering the entire understanding between the customer and the contractor.
contract documents Plans, specifications, and other documents that together set forth the requirements of the contract and become legally enforceable when the agreement is signed. Executed agreements between owner and contractor that become part of the contract when the agreement is signed. (CSI)
control module (CM) A unit that provides addressable outputs for signaling devices (e.g., fire alarm horns, speakers).
controlled access The process in which access to the resources of an area or system is limited to authorized personnel, users, programs, processes, or other systems and denied to all others.
convergence The linking of many systems, which remain independent in operation, to common information transport systems. As related to electronic safety and security, convergence involves many similar and dissimilar systems and facilitates their integration.See also integration.
converter 1. A device that changes a signal from one transmission medium type to another (e.g., from copper to optical fiber). 2. A device that changes from one signaling type to another (e.g., analog to digital).
coordinated protection The application of protection engineering across a set of premises systems to prevent electrical failure of telecommunications cabling and equipment.
core The central, light-carrying part of an optical fiber through which light pulses are transmitted.
core area See building core. (TIA)
core wall Building structure that runs from the structural floor to the structural ceiling to separate the core area from the rest of the building.
coupled bonding conductor (CBC) A bonding conductor placed (e.g., strapped) on the outside surface of telecommunications cable; used to reduce transient noise.
coupler A device for connecting two other devices (e.g., connectorized cables) together.
coupling The electromagnetic energy transfer from a disturbing circuit or channel into a disturbed circuit or channel due to either separated or combined influence of electric and magnetic fields.
cross-connect A facility enabling the termination of cable elements and their interconnection or cross-connection. (TIA)
cross-connection A connection scheme between cabling runs, subsystems, and equipment using patch cords or jumpers that attach to connecting hardware on each end. (TIA)
cross-coupling The coupling of a signal from one circuit or conductor to another.
crossover The junction unit at the point of intersection of two cable trays, raceways, or conduit (pathways) on different planes. (TIA)
crosstalk Unwanted transfer of signal from one or more circuits to other circuits as a result of electromagnetic interference.
current (I) Flow of electrons in a conductor measured in amperes.
customer premises equipment (CPE) Telecommunications equipment located on the customer’s premises. (TIA)

data center A building or portion of a building whose primary function is to house a computer room and its support areas.
datagram A piece of message sent over a packet switching network containing the address.
data network An interconnected system of computers, peripherals, and software over which commands, files, and messages are sent and received.
data transfer rate The rate at which information is transferred between network devices over a communications channel. Also called throughput or operating speed.
DB## connector A connector widely used for connections between data equipment, available in a variety of configurations (e.g., DB15, DB25). Also called a D-subminiature connector.
dB(A) Decibels (dB) above reference noise, adjusted for frequency (with F1A weighting). Adjusted reference noise is equivalent to a 1004 hertz (Hz) test tone at –85 dBm.
dBm 1. Decibel referenced to 1 milliwatt (mW); 0 dBm is equal to 1 mW; –10 dBm corresponds to 0.1 mW; –20 dBm corresponds to 0.01 mW; –30 dBm corresponds to 0.001 mW. 2. Psophometrically weighted noise power in decibels, with respect to a power level equivalent to an 800 Hz test tone at 0 dBm.
dBmV Decibel (dB) referenced to 1 millivolt often used in cable antenna television installations across 75 ohms.
dBrnc Decibels above reference noise (with C-message weighting). Reference noise is equivalent to a 1004 Hz test tone at –90 dBm.
decibel (dB) A logarithmic unit for measuring the relative voltage, power (in watts) or strength (in voltage or current) of a signal. A decibel is one tenth of a bel. See also bel.
dedicated in-floor service fitting See insert.
dedicated LAN A network on which a separate communications channel is assigned exclusively to each device by using switching technologies.
de facto standard An informal standard resulting from popular acceptance of a product or practice.
degradation The decline in operational performance.
delay skew The difference in propagation delay between the pair with the highest and the pair with the lowest propagation delay value within the same cable sheath.
delta (delta-connected power system A power system having none of the normal current-carrying conductors connected to ground.
demand priority An arbitration scheme that provides network access on the basis of the priority level of the message or sending device.
demarcation point (DP) 1. A point where the operational control or ownership changes. (TIA) 2. The point of interface between service providers and customer facilities.
demodulation The recovery of information from a modulated carrier of a signal having substantially the same characteristics as the original information.
demodulator An electronic device that removes information from a modulated signal.
demultiplexing The process of reconstituting the individual channels from the composite signal.
design-build construction When an owner contracts with a single entity employed to both design and build a project.
design development (DD) A design phase that follows a schematic design and is prior to construction documents.
design specification Documentation that defines a goal or set of goals including specific performance and design parameters.
despread The process of filtering out or shrinking a digitally coded signal to its original form in the direct sequence (pseudo-noise) technology.
detail drawing A detailed graphical representation of a specific area or element of construction, often not drawn to scale.
device address An address to uniquely identify each device on a network. The address is coded in the physical hardware. See also network address and medium access control (MAC) address.
dielectric A material that is nonmetallic and nonconductive used to insulate a conductor.
dielectric constant A unit of relative electric permittivity of an insulator.
dielectric strength Measures the maximum voltage that an insulation can withstand without breakdown.
differential-mode (DM) circuit The closed circuit for the intended signal current.
differential-mode voltage The symmetrical noise voltage that appears equally and in opposite phase in each active signal-carrying conductor. Contrast with common-mode voltage.
diffraction The bending of radio, sound, or lightwaves around an object, barrier, or aperture edge.
digital input (DI) The input to a device that receives a digital signal from an output device.
digital output (DO) The output of a device that sends a digital signal to an input device.

digital signal A signal that encodes information in the form of a sequence of discrete states. For example, a binary signal uses two states to encode the two states (0,1). Contrast with analog signal.
digital subscriber line (xDSL) A family of digital technologies designed to provide a variety of data transfer rates using different encoding and delivery methods. See also asymmetric digital subscriber line.
digital versatile disc (DVD) A high-density development of the compact disc, available in a number of formats and storage capacities.
direct broadcast satellite (DBS) A service that uses satellites to broadcast multiple channels of television programming directly to a small-dish antennas. direct-buried cable A telecommunications cable designed to be installed under the surface of the earth, in direct contact with the soil. (TIA) Contrast with underground
direct current (dc) A constant-value electric current that flows in one direction in an electric circuit.
direct current (dc) loop resistance Cable conductor resistance with the far end of the cabling shorted. This is the resistance for two conductors of a metallic cable.
direct digital control (DDC) A control loop used in building automation systems in which a microprocessor-based controller controls equipment (e.g., air handlers, chillers, boilers) based on sensor inputs and set-point parameters according to a sequence of operations.
directional antenna An antenna characterized by a broad coverage zone that preferentially sends or receives signals in a specific direction. See also omnidirectional antenna and unidirectional antenna.
directional coupler A device with one input port and two or ore output ports that splits a single input to multiple outputs while providing a high attenuation for reverse signals.
direct sound Sound that travels directly from a speaker to a listener.
discrimination The process of selecting the desired signal of the proper input level.
diskless work station A personal computer that depends upon a network server for loading data and applications. Diskless workstations are configured without a floppy or hard disk drive, thereby providing additional security.
dispersion 1. The loss of signal resulting from the scattering of light pulses as they are transmitted through a medium. 2. The widening or spreading out of the modes in a light pulse as it progresses along an optical fiber. 3. The characteristics of the sound coverage field of a speaker.
dissipation factor The relative power loss in the insulation due to molecular excitement and subsequent kinetic and thermal energy losses.
distributed antenna system (DAS) Systems that transmit or relay radio frequency signals (e.g., signals from cellular/personal communications system telephones, text pagers, wireless local area networks) within buildings, structures, tunnels, or other areas where wireless services cannot be otherwise provided.
distribution cable See horizontal cable.
distribution cell The cellular floor sections from which cables emerge into work areas.
distribution duct A raceway of rectangular cross-section placed within or just below the finished floor and used to extend the wires or cables to a specific work area. (TIA)
distribution frame A structure with terminations for connecting the cabling of a facility in such a manner that interconnection or cross-connections may be readily made. (TIA)
distribution panel A wiring board that provides a patch panel function and mounts either in a rack or on a wall.
diverse route An alternative routing for cables and/or services to provide a different pathway for resilience or security. See alternate route.
Division 1 A division in the Construction Specifications Institute (CSI) MasterFormat™ that standardizes the way information about a nonresidential construction project is organized. Division 1 is subordinate to the general conditions and supersedes part 1 of each section. (CSI)
downlink 1. Signals transmitted from satellites to ground stations. 2. In demand priority access method, the communications channel between a repeater and a connected end node or between a repeater and a lower-level repeater.
drag line Pull cord or line installed in a cable pathway. The line may be used for pulling in a stronger strength rope to pull cable(s) of greater mass and weight into the finished conduits. See pull cord.
draw Payment method for a telecommunications project in which the contractor receives an initial payment on commencement of the contract and makes periodic draws during the term of the project.
drip loop The length of cable, usually on the exterior of a building, placed above the entry hole of the building, extended to below the entry hole, and looped back up to the entry hole of the structure. The use of such cable installation will impede moisture infiltration.
drop and insert A process where a part of the information carried in a transmission signal passing through the repeater site is demodulated (dropped) to serve local consumers from the repeater site or information is inserted for further transmission.
drop cable 1. A branch cable. 2. The cable allowing connection and access to and from the trunk cable of a network.
drop ceiling See suspended ceiling.
dry pipe A pipe system that is fixed and installed permanently in place and distributed throughout an area of a floor or building for the purpose of delivering water in case of fire. Dry pipes are not normally filled with water until a fire alarm is activated, causing the pipes to fill with water to extinguish a fire; the pipes are thus normally dry and so named.
drywall An interior wall construction consisting of gypsum or plasterboard.
dual-duplex signaling A form of bidirectional signaling in which data transfer can flow in both directions at the same time over a single communications channel. See full-duplex signaling, half-duplex signaling, and simplex signaling.
duct 1. A single enclosed raceway for conductors, wires, or cables. See conduit and raceway. See also raceway. 2. An enclosure in which air is moved. Generally part of the heating, ventilating, and air-conditioning system of a building.
ductbank (DB) An arrangement of ducts, for wires or cables, in tiers. (TIA)
ducted skirting A cable raceway with a removable cover made of either wood, plastic, or metal found on the perimeter of walls of a building. May have separate channels for power in telecommunications. See raceway.
duplex A simultaneous two-way independent transmission in both directions. See also half-duplex and full-duplex signaling.

earth current Alternating or direct current that flows in the earth whether momentary, intermittent, or continuous.
earth ground An electrical connection to earth obtained by a grounding electrode system. See also approved ground and ground.
earthing electrode See grounding electrode.
earth potential rise (EPR) See ground potential rise.
easement A right acquired by one party to use land belonging to another party for a specific purpose.
effective ground Intentional connection to earth through a ground connection or connections of sufficiently low impedance (whose value is specified in suitable grounding/ earthing/bonding standards) and having sufficient current-carrying capacity to prevent the buildup of voltages that may result in undue hazards to connected equipment or to persons. (NEC)
elastomeric Characteristic of a material or substance allowing stretching and/or flexibility, resembling rubber or elastic.
elastomeric firestop A flexible firestopping material resembling rubber.
electric field strength A vector quantity fully described when its magnitude and direction are given. Electric field is expressed in volts per meter, and the direction of the electric field at each point in space is that in which a positive electrical charge placed at that point will move. See also voltage gradient.
electrical metallic tubing (EMT) Thin-wall metal tubing that does not have threaded ends, which is widely used in electrical distribution systems and as a pathway for telecommunications cabling.
electromagnetic compatibility (EMC) The ability of the design and operation of equipment in a manner that makes them immune to certain amounts of electromagnetic interference, while keeping the interference generated by them within specific limits.
electromagnetic disturbance Any electromagnetic occurrence that may degrade the performance of a device, unit of equipment, or system. An electromagnetic disturbance may be noise, an unwanted signal, or a change in the propagation medium.
electromagnetic emission The phenomenon by which electromagnetic energy emanates from a source. Emissions can be either radiated or conducted when coupled into a given disturbed circuit. Such emissions may be divided into two categories— intentionally emitted signals and unintentional electromagnetic emissions. See also
electromagnetic environment The electromagnetic field existing in a transmission medium.
electromagnetic immunity The ability of a device, equipment, or system to perform without degradation in the presence of an electromagnetic disturbance.
electromagnetic induction Current flow in telecommunications conductors produced by coupling of a magnetic field (e.g., by current in power lines, the cable shield, or other cable pairs).
electromagnetic interference (EMI) Radiated or conducted electromagnetic energy that has an undesirable effect on electronic equipment or signal transmissions. (TIA)
electromagnetic pulse (EMP) High-intensity electromagnetic radiation generated by a nuclear blast high above the earth’s surface and held to disrupt electronic and electrical systems.
electromagnetic radiation (EMR) Radiation made up of oscillating electric and magnetic fields and propagated with the speed of light. Includes gamma radiation, X-rays, ultraviolet, visible, and infrared radiation, radar, and radio waves.
electromagnetic spectrum The full range of electromagnetic emissions, which includes all light and radio waves.
electromagnetic susceptibility The inability of a device, equipment, or system to resist an electromagnetic disturbance.
electromagnetic wave A wave produced by the interaction of time-varying electric and magnetic fields.
Electronic Industries Alliance (EIA) An alliance organized along specific electronic product and market lines, and, as a standards association, develops and publishes industry guidelines.
electrostatic coupling The induction of electrical charges in electrical conductors that may be the result of capacitive coupling from the electric field (e.g., of a nearby power line).
electrostatic discharge (ESD) Electrical release of static electricity generated by interaction of dissimilar materials.
elevation drawing A two-dimensional graphical representation of a vertical plane (side view).
emergency power A stand-alone secondary electrical supply source not dependent upon the primary electrical source. (TIA)
emission The phenomenon by which electromagnetic energy emanates from a source. Emission can be either radiated or conducted. Such emissions may be divided into two categories—intentionally emitted signals and unintentional electromagnetic emissions.
emulation The technique of modifying a device with hardware or software to make it operate in the same manner as another device. See terminal emulation.
encoding The process of writing data to a card. See also signal encoding.
encroachment permit A legal document (usually issued by a government agency) that gives the permit holder permission to install and maintain facilities over or under the property designated by the permit.
end-of-line resistor (EOLR) Resistor that permits active monitoring of a two-wire circuit by using low-level circuit current to detect a short or break.
energy management system (EMS) A computerized monitoring and control system used to manage and provide operational efficiency for electrical power, heating, ventilating, and air-conditioning, and lighting control systems.
engine generator A unit that uses a fuel-powered engine to drive a rotary generator to produce electrical power.
engineered judgment by a professional for a slight variance.
entrance facility (EF) 1. An entrance to a building for both public and private network service cables (including wireless) including the entrance point at the building wall and continuing to the entrance room or space. (TIA) 2. A facility that provides all necessary mechanical and electrical services for the entry of telecommunications cables into a building and that complies with all relevant regulations. (ISO)
entrance room or space A space in which the joining of inter or intrabuilding backbone facilities takes place. (TIA)
equalizer An electronic device that compensates for the selective frequency losses of the cable that feeds into it.
equal level far-end crosstalk (ELFEXT) Crosstalk measured at the opposite end from which the disturbing signal is transmitted, normalized by the attenuation contribution of the cable or cabling.
equipment cable A cable or cable assembly used to connect equipment to horizontal or backbone cabling. (TIA)
equipment grounding conductor The conductor used to connect the noncurrent carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment.
equipment room (ER ) An environmentally controlled centralized space for telecommunications equipment that usually houses a main or intermediate cross-connect. (TIA)
error Any unwanted change in the original contents of a transmission.
errors and omissions (E&O) The failure to include or accurately define a requirement in a design document.
Ethernet A LAN protocol using a logical bus structure and carrier sense multiple access with collision detection. Ethernet standards are formulated by the IEEE 802.3 committee and apply to Open Systems Interconnection Reference Model Layers 1 and 2.
European economic area (EEA) An area composed of European Union, Iceland, Norway, and Liechtenstein.
exothermic weld A method of permanently bonding two metals together by a controlled heat reaction, resulting in a molecular bond. (TIA)
expansion joint A joint between adjoining surfaces (e.g., concrete, conduit) arranged to permit expansion and contraction with changes in temperature.
exposed Capable of being inadvertently touched or approached near than a safe distance by a person. It is applied to parts that are not suitably guarded, isolated, or insulated. (NEC)
exposed facilities Any cable facilities subjected to such effects as lightning, power crosses, power induction, or differences in ground potential.

fading The variation in path loss between the transmitter at one station and its normal receiver at the following station.
false ceiling See suspended ceiling. (TIA)
far-end crosstalk (FEXT) loss A measure of the unwanted signal coupling from a transmitter at the near end into another pair measured at the far end, and relative to the transmitted signal level. Also called input/output far-end crosstalk loss. (TIA)
fault tolerance The ability of a system to continue operations after the failure of one or more components or communications paths.
fault voltage (current) See foreign voltage (current).
Federal Communications Commission (FCC) Regulatory body for United States (U.S.) interstate telecommunications services and international service originating in the U.S.
feedback An unwanted oscillation or tone that quickly increases in loudness.
feeder duct See header duct and trench duct.
ferroresonance The resonance of iron molecules due to the application of a magnetic field that produces a magnetic flux on the iron structure. This is the principle of operation of transformers.
ferroresonant transformer A device that gives regulated alternating current (ac) voltages, capable of acting as a step-up or step-down voltage transformer and as an ac voltage regulator.
ferrule (optical fiber) The alignment sleeve portion of an optical connector used to protect and align the stripped optical fiber.
fiber See optical fiber.
fiber optics A communications system that uses optical fiber as its media.
Fibre Channel A high-speed, network point-to-point network protocol commonly associated with storage area network technologies.
field order (FO) Allows the engineer to authorize or order minor variations in the work when such changes do not involve a change in contract price or contract time. These orders must be in writing, but do not require an executed change order or the owner’s signature. (CSI)
fill 1. A sequence of added bits used to meet timing, sizing, or spacing requirements in and between messages. 2. Use of material (or material used) to equalize or raise earth topography to a certain elevation.
fire alarm (FA) A system that provides a reasonable level of safety by reducing the probability of injury and loss of life from fire, smoke, and heat in buildings by providing detection, suppression, and notification functions.
fire alarm control panel (FACP) A system-level controller that initiates sequences of operation for fire detection, suppression, and notification functions.
fire break A fire-rated material, device, or assembly of parts installed along a cable, other than at a cable penetration of a fire-rated barrier, to prevent the spread of fire along a cable. (TIA)
fireproof A property of a material (e.g., masonry, block, brick, concrete, and drywall) that does not support combustion even under accelerated conditions. No material is entirely fireproof.
fire-rated door A door assembled of various materials and types of construction used in wall openings to retard the passage of fire. These doors are rated in hours or fractions of hours.
fire rating system See fire resistance rating.
fire resistance A property of a material or assembly of materials that can withstand combustion and delay the passage of flame for some known period of time.
fire resistance rating The time in hours, or fraction thereof, that a material or assembly of materials will withstand the passage of flame and the transmission of heat when exposed to fire under specified conditions of test and performance criteria. (TIA)
fire retardant (FR) Any substance added to delay the start of fire ignition or to slow the spread of flame by the burning material.
fire shield A fire-rated material, device, or assembly of parts between pathways (e.g., between two parallel cable trays or between layers in vertically stacked trays) to prevent propagation of flames from one pathway to an adjacent pathway. (TIA)
firestop A fire-rated material, device, or assembly of parts installed in a penetration of a fire-rated barrier. (TIA)
firestopping The process of installing (specialty) listed fire-rated materials into penetrations of fire-rated barriers to reestablish the fire-resistance rating of the barrier. (TIA)
firestop seal See firestop system. (TIA)
firestop system A specific installation consisting of the material(s) (firestop penetration seals) that fill the opening in the wall or floor assembly, and around and between any items that penetrate the wall or floor (e.g., cables, cable trays, conduit, ducts, pipes), and any termination devices (e.g., electrical outlet boxes) along with their means of support.
firewall 1. A continuous barrier used to prevent fire spreading from one fire zone or area to another. 2. One or more security mechanisms (hardware and/or software) designed to prevent, detect, suppress, and/or contain unauthorized access to a network.
fire zone A contained area completely enclosed by fire-resistant rated walls, floors, and ceilings.
float current The current that is drawn by a battery when it is being kept in a fully charged state. The float voltage will determine this current. See float voltage.
float voltage The voltage at which a battery is maintained (floated) in order to keep it in a fully charged state. See float current.
floor distributor (FD) The distributor used to connect horizontal cable and cabling subsystems or equipment. International equivalent term for horizontal cross-connect.
floor plan 1. A scaled diagram or plan of a building floor or other structure. 2. Plan showing the layout of a building floor.
floor slab 1. That part of a reinforced concrete floor, which is carried on beams below.
(TIA) 2. A concrete mat poured on subgrade serving as a floor rather than as a structural member.
foil twisted-pair (FTP) cable See screened twisted-pair cable.
foreign voltage (current) Any unwanted voltage (current) imposed on a system that is not supplied from the central office or from telephone equipment, or from within the system itself. Also called fault voltage (current).
frame A data unit created at the Data Link layer of the Open Systems Interconnection model. It contains the data and control information necessary to transfer a message from one device to another on the same network.
free space loss The signal loss that occurs between two isotropic antennas in free space, unaffected by blocking, refraction, diffraction, or absorption.
free space optics (FSO) Low-power laser beam used for outdoor point-to-point highrate protocol-independent transmission.
frequency (freq) The number of cycles that a periodic signal completes in a given time; if the unit of time is one second, the frequency is stated in hertz (Hz). One Hz is equal to one cycle per second.
frequency band A range of communications frequencies.
frequency modulation (FM) Modulation in which the instantaneous frequency of a sine wave carrier is caused to depart from the center frequency by an amount proportional to the instantaneous value of the modulating signal. In FM, the center frequency is called the carrier frequency.
Fresnel zone The circular zone about the direct path between an electromagnetic wave transmitter and receiver in an unbounded transmission medium free of radiation sources.
frost lift Ground buckling upward as a result of heavy frost.
frost line The deepest level below grade to which frost penetrates in a particular geographic area. Usually specified in 50-year increments.
full-duplex signaling The transmission of data in two directions simultaneously. See also dual-duplex signaling, half-duplex signaling, and simplex signaling.
furniture system Furniture walls combined with furniture units designed to form a work area (e.g., a cubicle).
furniture wall A component of a furniture system.
fuse An overcurrent protective device with a circuit-opening fusible element that is severed (open) when heated by the passage of an overcurrent. Fuses are normally onetime devices; once they are open, they are not reusable.
fuse cable A length of cable that is two gauges smaller than the conductors of the cable being protected and at least 0.6 m (2 ft) long. Fuse cable is inserted in the plant and intended to open on excessive foreign power currents, thus protecting the station wiring cable or apparatus. Fuse cable does not protect against lightning currents or sneak currents. Also called fuse link.
fusing 1. The process of joining fibers together by fusion or melting. 2. The process of joining materials through a chemical or heating process. This fusing can occur as an unwanted action that can appear as an open or a short.
fusion splice A permanent joint accomplished by applying localized heat sufficient to fuse or melt the ends of two optical fibers together, forming a continuous single fiber.

Gantt chart A simple chart that diagrams a project schedule.
gas tube protector An overvoltage protector featuring metallic electrodes that discharge in a gas atmosphere within a glass or ceramic envelope. This type of protector does not require replacement each time it discharges.
gateway An internetworking service that is used to connect dissimilar applications running on different networks with different communications protocols. Gateways normally operate at one or more of the top four layers of the Open Systems Interconnection Reference Model. See also portal and wireless LAN gateway.
general conditions Any of a number of standards or code documents published that are applicable to the project delivery method.
general requirements See Division 1.
Gigabit Ethernet (GbE) A LAN protocol with a data transfer rate of 1000 Mb/s (1 Gb/s).
gigahertz (GHz) A unit of frequency denoting one billion cycles per second. See also hertz (Hz).
global area network (GAN) A network of different interconnected computer networks spanning an unlimited number of geographically distinct cities.
graded-index fiber An optical fiber design in which the refractive index decreases continuously from the center of the core to the outside of the core.
grommet Generally a rubber insulator used to protect a wire passing through an aperture. See also bushing.
ground A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of earth. (TIA) See also approved ground and earth ground.
grounded Connected to earth or to some conducting body that serves in place of the earth.
grounded conductor A system or circuit conductor that is intentionally grounded.
ground electrode See grounding electrode.
ground fault circuit interrupter (GFCI) A device intended for the protection of personnel that functions to de-energize a circuit or portion thereof, within an established period of time, when a current to ground exceeds the values established for a Class A device. (NEC)
grounding See grounded.
grounding bushing A fitting for attaching a ground wire to a conduit.
grounding conductor A conductor used to connect the grounding electrode to the building’s main grounding busbar. (TIA)
grounding electrode 1. A conductor, usually a rod, pipe, or plate (or group of conductors), in direct contact with the earth for the purpose of providing a low-impedance connection to the earth. (TIA) 2. A device that establishes an electrical connection to the earth. (NEC)
grounding electrode conductor (GEC) The conductor used to connect the grounding electrode to either the equipment grounding conductor, or to the grounded conductor of the circuit at the service equipment, or at the source of a separately derived system. (TIA)
grounding electrode system One or more grounding electrodes bonded to form a single reliable ground for a structure.
grounding equalizer (GE) A conductor that interconnects elements of the telecommunications grounding infrastructure (formerly telecommunications bonding backbone interconnecting bonding conductor).
grounding mat An extensive system of bare conductors, buried below the surface of the earth, intended to provide a low-resistance connection to earth and to equalize the potential within the area covered. (TIA)
grounding system A system of hardware and wiring that provides an electrical path from a specified location to an earth ground point.
grounding terminal A suitable bar, bus, terminal strip, or binding post terminal where grounding and bonding conductors can be connected.
ground loop Interference in electrical communication links due to the ground at each end being at different potentials.
ground potential The zero reference level used to apply and measure voltages in a system.
ground potential rise (GPR) A voltage difference between a grounding electrode system and the earth return currents produced by a lightning strike or a power fault current.
ground resistivity The measured direct current resistance of a volume of earth.
ground wave A low-frequency radio wave that bends along the earth’s surface rather than traveling through the atmosphere.
ground wire See bonding conductor and bonding conductor for telecommunications.
guaranteed maximum price (GMP) Bidders may be required to state a GMP that is not to be exceeded. This allows the owner an understanding of the absolute maximum cost of the project before start of construction.
guy A steel stranded wire used to provide counter tension to the pole opposite that of the installed cable pull tension to keep the pole upright.

half-duplex signaling A bidirectional signaling method in which data transfer can take place in either direction, but in only one direction at a time. Contrast with dual-duplex signaling, full-duplex signaling, and simplex signaling.
handhole (HH) A structure similar to a small maintenance hole in which cable can be pulled, but not large enough for a person to fully enter to perform work.
handoff The process that occurs when a mobile user moves from one cell (thereby terminating communications) to another cell (thereby initiating communications) in a cellular network. The handoff is accomplished without disruption of the exiting connection.
handover See handoff.
handshaking A connection-oriented protocol. The process whereby verification is established before controlled data is sent to a remote system. When handshaking is successful, the systems establish connection.
hardened The condition of a facility with protective features that enables it to withstand destructive forces (e.g., explosions or natural disasters).
hard-line trunk A rigid coaxial cable, typically used for backbone cabling. (TIA)
hard-sheath cable A cable or wire contained within a continuous inner or outer metallic sheath. (TIA)
headend The equipment located at the start of a coaxial cable distribution system where the signals are processed and combined prior to distribution.
header duct (trench duct, feeder duct) A raceway of rectangular cross-section placed within the floor to tie distribution duct(s) or cell(s) to the telecommunications room. (TIA)
heat coil A device that grounds a conductor when the conductor’s current time limits are exceeded.
hertz (Hz) A unit of frequency equal to one cycle per second.
high-rise building A multistory building (at least three stories) of structural steel or reinforced concrete construction.
home run A pathway or cable between two locations without a splice or intermediate termination points in between.
horizontal cable Distribution media that connect the telecommunications outlet/connector at the work area and the first piece of connecting hardware in the horizontal cross-connect (floor distributor).
horizontal consolidation point/telecommunications outlet cable A segment of horizontal cable between the consolidation point connector and the telecommunications outlet/connector. This cable should be easily moved for modular office rearrangement.
horizontal cross-connect (HC [floor distributor (FD)]) A group of connectors (e.g., patch panel, punch-down block) that allows equipment and backbone cabling to be cross-connected with patch cords or jumpers. Floor distributor is the international equivalent term for horizontal cross-connect.
horizontal HC-CP cable The segment of horizontal cable permanently installed between the horizontal cross-connect (HC) and the consolidation point (CP) connector.
horizontal pathway See pathway.
hub A network device that provides a centralized point for LAN communications, media connections, and management activities of a physical star topology cabling system.
hybrid cable An assembly of two or more cables, of the same or different types or categories, covered by one overall sheath. (TIA) Contrast with bundled cable.
hybrid coupler A component used to combine two wireless bands to a single antenna feed or distribution cable.

ice load The weight factor calculated from the potential amount of ice that can build up on outside plant structures from storm conditions.
identifier (ID) An item of information that links a specific element of the telecommunications infrastructure with its corresponding record. (TIA)
immunity The ability of a device, equipment, or system to perform without degradation in the presence of an electromagnetic disturbance.
impedance The total opposition (resistance and reactance [capacitance and inductance]) that a circuit, cable, or component offers to the flow of alternating current at a given frequency. It is measured in ohms.
index of refraction (IOR) The ratio of the velocity of light in a vacuum to the velocity of a light in another medium. Also called refractive index.
inductance A condition that opposes the flow of current while causing a voltage phase shift in +90.
inductive coordination The cooperative effort of telecommunications and power company personnel in the engineering and application of measures and devices to ensure compatibility of operation between both systems for noise reduction and protection.
infrastructure (telecommunications) A collection of those telecommunications components, excluding equipment, that together provides the basic support for the distribution of all information within a building or campus. (TIA)
innerduct A nonmetallic raceway, usually circular, placed within a larger pathway. (TIA)
input impedance The ratio of the voltage at the sending end of the line to the current in the line at the sending end.
insert An opening into the distribution duct or cell from which wires or cables emerge. (TIA) See also insert, afterset and insert, preset.
insert, afterset An insert installed after the installation of the concrete floor slab or other flooring material. (TIA) See also insert; contrast with insert, preset.
insertion loss The signal loss resulting from the insertion of a component, or link, or channel, between a transmitter and receiver (often referred to as attenuation). (TIA) See also attenuation.
insertion loss deviation The difference between the actual insertion loss as measured on a permanent link or channel and the insertion loss as determined by adding the component losses. (TIA)
insert, preset An insert installed prior to the installation of the concrete floor stab or other flooring material. (TIA) See also insert; contrast with insert, afterset.
Institute of Electrical and Electronics Engineers, Inc.® (IEEE®) An international organization whose purpose is to advance global prosperity by promoting the engineering process of creating, developing, integrating, sharing, and applying knowledge about electrical and information technologies by the definition and application of standards.
insulating joint An opening in a cable sheath or down guy where continuity is deliberately interrupted to prevent the flow of currents.
insulation resistance The insulation’s ability to resist the flow of current through it. For inside conductors, insulation resistance is typically expressed in megohm•km or megohm•1000 ft.
integrated services digital network (ISDN) A fully digital communications facility designed to provide transparent end-to-end transmission of voice, data, audio/video, and still images across the public switched telephone network. Different versions exist for North America and Europe.
integration The seamless gathering of many similar and dissimilar systems as if they were one system. In relation to electronic safety and security, integration may involve the interconnection or convergence of components of these systems as well as other building, vehicle, or communications systems for purposes of data collection, monitoring, management, and control. See also convergence.
intelligent device (ID) Addressable device used to monitor and control functions in a building automation system network.
interbuilding (campus) backbone A backbone network providing communications between more than one building.
intercom/paging system A communications device used for either one-way or two-way voice broadcasts.
interconnection 1. A connection scheme that employs connecting hardware for the direct connection of a cable to another cable without a patch cord or jumper. 2. A type of connection in which single-port equipment connections (e.g., 4-pair and optical fiber connectors) attach to horizontal or backbone cabling by means of patch cord or jumper.
intermediate cross-connect (IC [building distributor (BD)]) The connection point between a backbone cable that extends from the main cross-connect (campus distributor [first-level backbone]) and the backbone cable from the horizontal cross-connect (floor distributor [second-level backbone]). Building distributor is the international equivalent term for intermediate cross-connect.
intermediate network A network used to connect two or more networks. See internetwork.
International Electrotechnical Commission (IEC) The commission responsible for international electronics standards.
International Organization for Standardization (ISO) The organization responsible for defining international cabling standards.
Internet A worldwide internetwork using TCP/IP (transmission control protocol/Internet protocol).
Internet protocol (IP) The Open Systems Interconnection Reference Model Layer 3 (Network layer) protocol most commonly used for internetworking. Required for communications over the Internet.
Internet service provider (ISP) An entity that provides or sells Internet services and/or access to the Internet.
Internet Society (ISOC) The organization that oversees the overall development of the Internet.
internetwork The connection of two or more networks.
internetworking Enables communications between devices attached to different networks.
interstitial space A small or narrow space located above or below the occupant’s space on each floor that is used for routing building services (e.g., lighting; heating, ventilating, and air conditioning; power; telecommunications; plumbing).
intrabuilding backbone cable Cable that runs between telecommunications rooms inside a building. Can be vertical or horizontal in physical orientation.
intranet A collection of users/servers designed to provide content, via methods similar to the World Wide Web, to a limited group of users, defined by security restrictions, on an internal network.
intumescent firestop A firestopping material that expands under the influence of heat. (TIA)
IP address The Network layer address assigned to devices using the Internet protocol. Also called an Internet address.
isoceraunic map A geographical map of a wide area (e.g., the United States) with continuous lines connecting points of equal thunderstorm-day activity that provides a relative comparison of the thunderstorm activity in one area to that of another area.
isochronous communication A signaling method where a set data transfer rate within a communications channel is guaranteed. See asynchronous communication and synchronous communication.
ISO/IEC Jointly develops and defines international cabling standards. See International Electrotechnical Commission and International Organization for Standardization.
isolation transformer A transformer with high galvanic insulation used to break ground loops at low frequency in communications systems operating over copper cables.
issuer The person or company that issues a request for quote or request for proposal.

jack A common term for telecommunications outlet/connector. See modular jack.
jack header A raceway similar to a header duct, usually provided in short lengths to connect a quantity of distribution ducts together. (TIA)
J-hook A supporting device for horizontal cables that is shaped like a J. It is attached to some building structures. Horizontal cables are laid in the opening formed by the J to provide support for the cables.
jumper 1. An assembly of twisted pairs without connectors, used to join telecommunications circuits/links at the cross-connect. (TIA) 2. An optical fiber cable with connectors installed on both ends. See also cable assembly and pigtail.
junction (spur) interference The point where a microwave path leaves the main route on the same tower and the main line slot or vice versa. The junction (spur) interferes with the main path slot.

key telephone system (KTS) ground terminal A screw terminal located on the key system power supply that must be connected to the grounding lug on the station protector.
kilohertz (kHz) One thousand cycles per second (hertz).
kilowatt (kW) A unit of electrical power equal to 1000 watts.
kilowatt hour (kWh) Watts indicate the amount of power that is consumed by a circuit during a given period of time. Utility companies charge for power in kWh.

ladder cable tray A prefabricated structure consisting of side rails connected at the bottom by transverse members (rungs) for supporting and routing cables or conductors within the structure.
ladder rack A device similar to a cable tray but more closely resembles a single section of a ladder. It is constructed of metal with two sides affixed to horizontal cross members.
ladder tray See ladder cable tray and cable tray.
LAN address See local area network (LAN) address and medium access control (MAC) address.
latency The time it takes for a signal to pass through a device or network (e.g., the delay between the time a switch receives a message on an input port and forwards it to an output port).
LC connector A small form factor (SFF) single fiber, optical fiber connector used for the termination of both multimode and singlemode optical fiber cables. A two-fiber, duplex connector option is also available. The housing mechanism of the LC connector (simplex and duplex) is a push-pull type connection.
legend A list of symbols and abbreviations on construction documents.
legend sheet A part of a drawing set, maintained by the architect and providing a list of standard symbols and abbreviations used throughout the document.
license An interest in property for a limited time and purpose.
lifting belt Safety device designed to be worn around the abdomen to help support the stomach muscles while encouraging proper posture.
light amplification by stimulated emission of radiation (laser) A device that produces coherent, highly directional light with a narrow range of wavelengths used in a transmitter to convert information from electric to optical form.
light-emitting diode (LED) A semiconductor diode that spontaneously emits incoherent light from the PN junction when forward current is applied. It converts information from electrical to optical form. An LED typically has a large spectral width.
lightning down conductor A metallic conductor running vertically down a building, connecting the air terminals, and equalizing conductors to the lightning ground terminals.
lightning equalizing conductor A closed metallic loop around the top and bottom of a building that aids in equalizing the potential of a lightning strike over the entire building and offers multiple connection points to the ground terminals.
lightning ground terminal A grounded metallic conductor installed for lightning protection.
lightning rod See air terminal.
limited common element (LCE) A portion of a dock that is accessible only to those boat slips that it serves on either side.
line cord Telecommunications equipment cord typically using stranded or tinsel conductor. See also work area cable (cord).
linearity A signal output voltage directly proportional to the signal input voltage.
line-of-sight (LoS) The imaginary line that connects the observer’s eye with the object the observer is looking at. See also Fresnel zone.
link A transmission path between two points, not including terminal equipment, work area cables, and equipment cables. Can be up to 90 m (295 ft) in length for horizontal cabling. See also permanent link test configuration.
link access device (LAD) An internetworking device used to convert LAN signals into a format suitable for transmission over a wide area internetwork link.
link aggregation A mechanism that combines multiple network communications channels into a single large channel to improve data transfer efficiency. Also called trunking. See also port aggregation.
listed 1. Equipment included in a list published by an organization, acceptable to the authority having jurisdiction (AHJ), that maintains periodic inspection of production of listed equipment, and whose listing states either that the equipment or material meets appropriate standards or has been tested and found suitable for use in a specified manner.
(TIA) 2. Buildings of historic/public interest that structurally cannot be altered or can only be altered with approval of the AHJ. 3. A product listed after it successfully completes a series of mechanical, electrical, and thermal characteristic tests that simulate all reasonable, foreseeable hazards.
load balancing A mechanism for distributing incoming requests among a collection of devices or circuits to reduce response times. A technology that complements server clustering. See cluster.
local A geographic zone large enough to encompass a multibuilding campus. See also metropolitan.
local area network (LAN) The standard industry term for a network installation that serves a relatively small area (e.g., structured cabling installation serving a building).
local exchange carrier (LEC) A telecommunications company that provides public switched network access service. (TIA) Can be referred to as incumbent local exchange carrier (ILEC) and competitive local exchange carrier (CLEC).
local multipoint distribution service (LMDS) A fixed wireless technology that operates in the 28 GHz band and offers line-of-sight coverage over distances up to 3.0 km to 5.0 km (1.9 mi to 3.1 mi). It can deliver data and telephony services to 80,000 customers from a single node.
local station A station that is directly connected to the network over cabling or wireless media. See also remote station and station.
logical topology 1. The path taken by messages as they travel from one device to another on a network. 2. The actual method (ring, bus, star) by which different nodes in a network communicate with one another as compared to the physical connections. Contrast with physical topology.
longitudinal noise Noise coupled due to electrostatic or electromagnetic fields that induces longitudinal currents into the disturbed circuit. See also common-mode voltage.
LonTalk® (Local Operating Network Talk) A protocol developed by the Echelon Corporation for interoperable control networks using the LonWorks® technology.
LonWorks is used for processing and communicating signals in distributed control networks consisting of intelligent devices (e.g., Neuron® chips).
loop 1. In telephone systems, the wire pair that connects the customer to the switching center. This path is called a loop because it is generally two wires electrically tied together through the customer terminal set when the customer goes off hook. 2. The outside plant facilities that extend from a serving main entrance facility or remote site to the exchange boundary. 3. A communications channel from a switching center or an individual message
distribution point to the user terminal.
loop diversity The placing of alternate facilities to back up the main system in case of failure. See alternate entrance.
loop loss The word “loop” in loop loss refers to the physical telecommunications circuit loop from a telephone company central office (CO) location to the customer premises equipment (CPE). This “loop” is effectively the round trip circuit between the CO and the CPE. Signal loss occurs between the CO and the CPE as a result of distance between the two points, cabling imperfections and resistance of the wire pairs. Loop loss refers to the
telecommunications circuit signal loss between the CO and the CPE.
loose tube A type of optical fiber cable construction where one or more fibers are laid loosely in a protective tube often filled with gel. Also called loose tube fiber.
low voltage disconnect (LVD) An electromechanical device designed to disconnect a battery from the load at a predetermined voltage.
low-wide building A building (e.g., a large shopping mall, factory, warehouse). The private branch exchange and key systems may be remotely located from the entrance facility protector, creating the need for special attention to grounding and bonding.
lump sum Payment method for a telecommunications project in which the contractor is paid the full amount upon completion and acceptance of the work.

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Old 12-10-2008 - Glossary and Definitions - Networking Computer Systems - Computer Networking Systems - Genaral - Voltage Talk forum
Brigette Power
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magnetic field strength The magnitude of the magnetic field vector expressed in amperes per meter (A/m).
main cross-connect (MC [campus distributor (CD)]) The cross-connect normally located in the (main) equipment room for cross-connection and interconnection of entrance cables, first-level backbone cables, and equipment cables. Campus distributor is the international equivalent term for main cross-connect.
main terminal room See main terminal space. (TIA)
main terminal space The location of the cross-connect point of incoming cables from the telecommunications external network and the premises cable system. (TIA)
maintenance hole (MH) (telecommunications) 1. A vault located in the ground or earth as part of an underground duct system and used to facilitate placing, connectorization, and maintenance of cables as well as the placing of associated equipment, in which it is expected that a person will enter to perform work. (TIA)
Formerly called manhole. 2. A hole through which an underground or enclosed structure may be used.
managed personal computer (PC) A personal computer having hardware and software features that allow it to be remotely monitored and configured over a network by a central computer.
Manchester encoding A digital encoding scheme where a voltage transition occurs in the middle of each binary digit sent. A high-to-low transition represents the binary digit zero and a low-to-high transition represents the binary digit one.
manhole See maintenance hole (MH) (telecommunications).
MasterFormat™ Jointly developed by the Construction Specifications Institute and Construction Specifications ; it is an organizational structure providing numbers and titles for the variety of subject matter necessary for the construction, operation, and maintenance of a facility. (CSI)
material safety data sheet (MSDS) Information system describing hazardous chemicals and materials.
measurement accuracy The possible difference between the measured value and the actual value of the parameter.
mechanical splicing The joining of two optical fibers through mechanical means to enable a continuous signal.
media (telecommunications) Wire, cable, or conductors used for telecommunications. (TIA) See also transmission media.
medium 1. The transport media through which network devices communicate with each other. 2. A material (e.g., magnetic disk) on which data may be stored.
medium access control (MAC) address A hexadecimal identifier, unique to each device on a LAN.
megabit per second (Mb/s) A transmission rate denoting one million bits per second.
megahertz (MHz) A unit of frequency equal to one million cycles per second (hertz).
megahertz•kilometer (MHz•km) The expression of optical fiber cable bandwidth where half power is realized at a specific point in frequency at 1 kilometer (e.g., 160 MHz•km @ 850 nm and 500 MHz•km @ 1300 nm).
megaohmmeter 1. An instrument used to measure resistance. 2. A portable instrument used to measure insulation resistance.
megger 1. A device that can be used to measure electrical resistance in a grounding system. 2. A testing unit used to generate a high voltage between cable conductors to detect current leakage between conductors or conductor to ground.
membrane penetration An opening through only one surface or side of a barrier. (TIA)
mesh topology A topology where each device or network is connected to all other devices or networks by multiple paths.
messenger See support strand (messenger).
metropolitan A geographic zone (e.g., a city, town, or municipal area). See metropolitan area network.
metropolitan area network (MAN) A data communications network that covers an area larger than a campus area and smaller than a wide area network.
micron (μm) 1. A unit of length equal to one millionth of a meter. 2. An abbreviation for micrometer.
microprocessor-based controller A controller that uses a microprocessor to perform logic and control functions in a building automation system network. Typically controls or monitors a specified building area through wired devices and resident software, but also has the ability to communicate with other controllers via a communications bus.
microsegmentation The technique used to divide a network into multiple small networks to improve performance. Ultimately, each device can have its own dedicated LAN through an exclusive connection to a switch port.
Mie scattering A phenomenon related to free space optics that describes light scattered by particles the size of the optical wavelength (e.g., fog).
mil A unit of length equal to 0.0254 mm (0.001 in), used in measuring the diameter of wires.
mode Loosely, a possible light path followed by light rays, as in multimode or singlemode. Strictly, a distribution of electromagnetic energy that satisfies Maxwell’s equations and boundary conditions in guided wave propagation.
modification (contract) A document issued after a contract has been awarded that alters, adjusts, or limits the terms or requirements of the agreement (contract).
modular jack A female telecommunications connector (socket) that may be keyed or unkeyed and may have six or eight contact positions. (TIA)
modulation 1. Any of several techniques (e.g., AM and FM) used to modulate a carrier signal with an information-bearing signal. 2. The process of coding and decoding information for transmission.
modulator An electronic device that modulates baseband video, audio, and data signals to specific carrier frequencies for insertion into the broadband radio frequency distribution system.
monolithic pour The single, continuous pouring of a concrete floor or columns of any given floor of a building structure. (TIA)
monolithic slab The result of a monolithic pour. (TIA)
motor control center (MCC) Electrical unit typically located in the main electrical room primarily used to control mechanical equipment (e.g., motors, pumps, compressors).
MT-RJ connector A small form factor (SFF) multi-fiber, optical fiber connector used for the termination of both multimode and singlemode optical fiber cables. The housing mechanism of the MT-RJ connector is a push-pull type connection.
multi-dwelling unit (MDU) Category includes apartments, townhouses, condominiums, and assisted-living facilities. These facilities may be under a single roof or consist of multiple buildings in a residential campus.
multi-dwelling unit telecommunications room (MDU-TR) Space where backbone and auxiliary disconnect outlet cables terminate to support multiple living units.
multiground neutral (MGN) system A utility power system where the neutral conductor is continuously present along with the phase conductors. The neutral conductor is connected to earth periodically along its path, typically, four times per 1.6 km (1.0 mi).
multimeter Test equipment that can be set up to perform a variety of electrical property measurements, usually including resistance, voltage, and current.
multimode optical fiber An optical waveguide that allows many bound modes to propagate.
multiple access 1. A scheme that allows users to share the same channel instead of each being assigned separate, unique channels. 2. In satellite communications, the capability of a satellite to function as part of a link between more than one pair of satellite terminals.
multiple prime contract When the owner divides the work among several contractors and enters into a separate contract with each.
multiplex (mux) Combining two or more signals into a single wave (the multiplex wave) from which the signals can be individually recovered. See also multiplexing.
multiplexer (mux) A device that combines two or more signals over a single communications channel (e.g., time-division multiplexing and wavelength-division multiplexing).
multiplexing (muxing) The combining of two or more communications channels into a common, high-capacity channel from which the original signals may be individually recovered.
multi-user telecommunications outlet assembly (MUTOA) A grouping in one location of several Telecommunications outlet/connectors. (TIA)

N type or N connector A medium-size threaded coaxial connector for use with direct current through 11GHz with Series-8, thicknet, and Series-11U coaxial cables. It features a characteristic 50 ohm impedance structure. N-type connectors have a center pin that must be installed over the cable’s center conductor.
nanometer (nm) 1. A unit of length equal to one billionth of a meter. 2. The most common unit of measurement for optical fiber operating wavelengths.
narrowband Any analog signal or analog representation of a digital signal whose essential spectral content is limited to that which can be contained within a voice channel of nominal 4 kHz bandwidth. Narrowband radio uses a voice channel with a nominal 3 kHz bandwidth.
National Electrical Code® (NEC®) A safety code written and administered by the National Fire Protection Association (NFPA®).
National Fire Protection Association, Inc. (NFPA®) Association that writes and administers the National Electrical Code® (NEC®).
near-end crosstalk (NEXT) loss 1. The unwanted signal coupling between pairs. It is measured at the end of a cable nearest the point of transmission. Contrast with far-end crosstalk. 2. The signal transfer between circuits at the same (near) end of the cable.
NetPC A device similar to a personal computer with respect to processing power, memory capacity, and graphics capabilities but lacking removable storage devices such as diskette drives. See network computer.
network A series of controllers, all connected via a telecommunications cable.
network address A Layer 3 address used to uniquely identify each LAN connected to an internetwork. See also media access control (MAC) address.
network administration The set of tasks performed to provide secure and reliable access to selected network resources.
network computer (NC) A device similar to a personal computer with respect to processing power, memory capacity, and graphics capabilities but lacking any storage capabilities (no built-in diskette or hard disk drives). See also thin client.
network interface (NI) 1. The point of connection between a user terminal and a private or public network. 2. The point of interconnection between the public switched network and a privately owned terminal.
network interface card (NIC) Circuitry in a device that provides the means to physically connect to the network.
network interface device (NID) The point of connection between networks. (TIA)
network operating system (NOS) An integrated collection of software programs designed to control and coordinate all access to network resources. It enables the sharing of software applications, peripheral devices, communications services, and user-created files by authorized network users.
noise An unwanted electrical signal on a wire that provides a random or persistent disturbance that interferes with the clarity or quality of the expected signal and alters the shape of the signal.
nominal velocity of propagation (NVP) The coefficient used to determine the speed of transmission along a cable relative to the speed of light in a vacuum.
noncollusion statement A document often required with the submission of a bid certifying that the bidder has not conferred, conveyed, or otherwise communicated with another party in an attempt to restrict competition.
non-power limited (NPL) Refers to 115 volts alternating current power circuits.
non-power-limited fire alarm (NPLFA) In the United States, a fire alarm system using 115 volts alternating current power circuits for control rather than reduced voltage.
nonzero dispersion shifted A type of optical fiber designed to introduce a small amount of dispersion without a zero point crossing being in the wavelength division multiplexer passband. With this type of optical fiber, it is possible to eliminate, or at least greatly reduce the degradation due to four-wave mixing, a distortion mechanism that requires the spectral components to be phase matched along the optical fiber.
numerical aperture (NA) 1. A number that expresses the light-gathering ability of an optical fiber, defining the maximum angle to the fiber axis at which light will be accepted and propagated through the fiber. NA = sin q, where q is the acceptance angle. 2. Describes the angular spread of light from a central axis, as in exiting a fiber,
emitting from a source, or entering a detector.

Occupational Safety and Health Administration (OSHA) United States (U.S.) agency that develops and enforces safety and health standards that apply to the work conditions, practices, means, methods, operations, installations, and processes performed in U.S. workplaces, including telecommunications locations and at telecommunications field installations.
ohm Unit of measure of electrical resistance; one ohm is defined as the resistance that allows one ampere, the unit of electric current to flow when one volt is applied.
Ohm’s law The mathematical relationship among electric current, resistance, and voltage. The voltage in volts is equal to the current in amperes multiplied by the resistance in ohms.
ohmmeter A device used to measure voltage and resistance.
omnidirectional Radiating in all directions for the source signal.
omnidirectional antenna An antenna characterized by a broad coverage zone that radiates signals in all directions equally. See directional antenna and unidirectional antenna.
open invitation request for quote (RFQ) An invitation to any company, of any size, reputation, or capability, to respond to an RFQ (e.g., bid on a project).
open office A floor space division provided by furniture, movable partitions, or other means instead of by building walls. (TIA)
open office cabling The cabling that distributes from the horizontal cross-connect (floor distributor) to the open office area utilizing a consolidation point or multiuser telecommunications outlet/connector.
Open Systems Interconnection (OSI) Reference Model A seven-layer architecture developed by the International Organization for Standardization that has served as a foundation for the development of many standards for network systems communications. The seven layers are physical, data link, network, transport, session, presentation, and application.
operating system (OS) Software that controls the execution of all programs and the utilization of resources on a device such as a personal computer.
optical fiber A transmission media using a thin filament of glass or plastic to transmit pulse light signals. Its bandwidth is higher than copper and not subject to electromagnetic interference. The optical fiber consists of a central core (glass or plastic) and an outer cladding. See also plastic optical fiber.
optical fiber cable Cable made up of one or more strands of glass consisting of a central core and outer cladding (optical fibers), strength members, and an outer jacket.
optical fiber cladding See cladding.
optical fiber core See core.
“or equal” Used to identify a level of quality or feature(s) of a specific product or assembly that can be substituted but must be equivalent to the specified product in every way. Better phrases are “or as approved” or “or approved substitute.”
outer protection An outer layer of material, composed of armored wire or metallic tape, covering the sheath of the cable.
outlet box (telecommunications) A metallic or nonmetallic box mounted within a floor, wall, or ceiling and used to hold telecommunications outlets/connectors or transition device. (TIA)
outlet cable (OC) A cable placed in a residential unit extending directly between the telecommunications outlet/connector and the distribution device. (TIA)
outlet/connector (telecommunications) A connecting device in the work area on which horizontal cable or outlet cable terminates. (TIA)

packet Bits grouped serially in a defined format containing a command or data message sent over a network. A generic term used to describe a unit of data at any layer of the Open Systems Interconnection Reference Model protocol stack. See also frame and datagram.
packet switching A data communications switching and transmission system in which an input data stream is broken down into uniform data packets. Each packet is transmitted independently between devices through the network without first establishing a dedicated communications path between the devices. At the receiving end, the packets are checked for errors, resequenced as necessary, and combined into an output data stream. Contrast
with circuit switching.
PageFormat™ A guide published by the Construction Specifications Institute (CSI) that describes the recommended arrangement of text on a specification page; provides a system for designating articles, paragraphs, and subparagraphs; and includes guidance for page numbering, margins, and other aspects of formatting. (CSI)
partitioned local area networks (LANs) Typically configured with LAN user traffic separated through virtual LAN (VLAN) port assignments based on a clients identity. VLANs allow a single physical LAN to be partitioned into several smaller logical LANs.
patch cord A length of cable with connectors on both ends used to join telecommunications circuits/links at the cross-connect. (TIA)
patch cord adjuster A mechanical device to which a patch cord is mated that enables the cord to be managed within the patch cord field. Permits the bend radius of the cable to be controlled and allows for periodic readjustment of the length of the patch cord.
path loss In a communications system, the attenuation undergone by an electromagnetic wave in transit between a transmitter and a receiver. It may be caused by many effects such as free-space loss, refraction, reflection, aperture-medium coupling loss, and absorption.
pathway 1. A sequence of connections that provides the connectivity between devices on a network or between networks on an internetwork. 2. The vertical and horizontal route of the telecommunications cable. 3. A facility for the placement of telecommunications cable. (TIA)
peak power (PP) Maximum electrical energy available in an alternating current. It is a factor of voltage multiplied by the current (amperage). See average power and power.
pedestal A protective aboveground enclosure used most commonly to house a splice point or administrative terminal location.
peer-to-peer LAN A network environment where any station can contribute to or access network resources. All network devices function as equals.
penalties (contract) Fines levied by a customer against a contractor for failure to complete a project by the specified date.
penetration Opening made in a firestop barrier. See membrane penetration and through penetration.
penetration seal See firestop system. (TIA)
performance bond A bond that ensures a contractor will use specified methods and procedures in performing a project.
period The smallest repetitive interval of a periodic waveform (e.g., time for one cycle of a sine wave).
peripheral device External equipment connected to and controlled by a station or a server (e.g., CD-ROM drives, modems).
permanent link A test configuration for a link excluding test cords and patch cords. (TIA)
permanent link test configuration The transmission path between two mated interfaces of generic cabling, excluding equipment cords, work area cords, and crossconnections but including the connecting hardware at each end. (ISO)
permeability The property of a magnetizable substance that determines the degree in which it modifies the magnetic flux in the region occupied by it in a magnetic field.
personal area network (PAN) A data communications system that covers an area generally associated with an individual workspace (e.g., office, cubicle).
PERT (program evaluation review technique) chart A network chart or logic diagram. Generally used by the project manager to see how one change in the project affects the remaining tasks.
phase The relationship in time between two waveforms of the same frequency.
phase modulation (PM) An angle modulation in which the phase angle of a carrier is caused to depart from its reference value by an amount proportional to the instantaneous value of the modulating signal.
physical topology The physical layout of a network as defined by its cabling architecture. Contrast with logical topology.
Picowatts of noise power Psophometrically weighted. 1.0 pWp is equivalent to an 800 Hz test tone at –90 dBm
pigtail One or more conductors or fibers with only one end terminated. (TIA) See also cable assembly and jumper.
PIII-500 A semi-rigid coaxial cable with an aluminum sheath that is typically used as a trunk cable in a CATV distribution network. This term is pronounced “P three five hundred.” PIII indicates the type of cable and 500 indicates the cable diameter (12.7 mm [0.5 in]).
PIN diode A positive-intrinsic-negative diode, used to convert optical signals to electrical signals in a receiver.
Planté cell Invented in 1859 by French physicist Gaston Planté, the lead acid storage battery uses a liquid electrolyte to generate current. The lead acid/calcium battery is the most commonly used battery for uninterruptible power supply backup. This type of battery generates hydrogen gas when charging. Because sulfuric acid electrolyte evaporates to some extent, these batteries must be used in a room that is well ventilated to the outside and kept away from delicate electronic equipment.
plastic optical fiber (POF) Optical fiber made of plastic rather than glass. See also optical fiber.
plenum A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system. (TIA).
point-to-multipoint A wireless connection from one point to several other points.
point-to-point (PTP) A direct connection established between two specific locations, as between two buildings or devices.
poke-thru Penetrations through the fire-resistive floor structure to permit the installation of horizontal telecommunications cables. (TIA)
poke-thru system A fire-rated device used to penetrate through the fire-resistive floor structure to permit the installation of electrical and/or telecommunications cable. (TIA)
polarization Orientation with respect to a given position, force, voltage, or direction. As with antennas, this is the direction of the radiated electric field in relation to the surface of the earth. This is generally vertical in mobile radio systems.
pole A column of wood, steel, fiberglass, or other material supporting overhead cables.
polyvinyl chloride (PVC) A tough, general purpose, flame-retardant, thermoplastic, water-resistant insulator used for wire and cable insulation and jackets.
port 1. A physical connection point on a network access device (e.g., hub, switch. 2. An identifier of an application process within the Transmission Control Protocol/Internet Protocol suite.
portable operator’s terminal (POT) A portable terminal used for maintenance and error detection in building automation systems.
portal An access point that connects a wireless LAN to another IEEE 802 network (e.g., Ethernet, token ring).
port aggregation A mechanism that combines multiple network communications channels into a single large channel to improve data transfer efficiency. See also link aggregation.
port density The number of modular connections within a space.
positive temperature coefficient (PTC) resistor A resistor whose resistance increases with temperature.
posttensioned concrete A type of reinforced concrete construction in which the embedded steel members are first put under tension, the concrete poured and allowed to harden, and the tension of the steel members released causing compression of the concrete. (TIA)
pothole See test hole.
power (P) 1. Rate of transfer or absorption of energy per unit time in a system. 2. Energy required to operate an electrical device (e.g., motor, amplifier, telephone transmitter). See also average power and peak power.
power arrester A device installed in power systems to limit the line-to-ground surge voltage due to a power surge or spike.
power-limited (PL) Refers to secondary power (subcircuit) reduced to 24 volt direct current or less for building automation system functions.
power-limited fire alarm (PLFA) Fire alarm systems that utilize low-voltage circuits (less than 24 volt).
power pole See utility column.
power splitter A passive device that accepts an input signal and delivers multiple output signals with specific phase and amplitude characteristics.
power sum Used to specify a combination crosstalk from multiple sources.
power sum attenuation-to-crosstalk ratio (PSACR) A ratio in dB, determined by subtracting the insertion loss from the power sum near-end crosstalk loss. (TIA)
power sum equal level far-end crosstalk (PSELFEXT) A computation of the unwanted signal coupling from multiple transmitters at the near-end into a pair measured at the far-end, and normalized to the received signal level. (TIA)
power sum near-end crosstalk (PSNEXT) loss A computation of the unwanted signal coupling from multiple transmitters at the near-end into a pair measured at the near-end. (TIA)
preset insert See insert, preset.
prevailing wage rate Labor rates published by state or federal governments that state the minimum allowable wage that can be paid to a laborer for a particular task, typically on a publicly funded project. The rates are published for each project and can vary from county to county and project to project.
prewiring 1. Cabling installed before walls are enclosed or finished. 2. Cabling installed in anticipation of future use or need. See also rough-in.
primary protector 1. A device that limits voltage between telecommunications conductors and ground (usually between 215 volt direct current [Vdc] to 350 Vdc).
2. A protective device placed on telecommunications conductors in accordance with codes and standards such as NFPA 70.
prioritization A function performed by a network interface card that makes it possible to assign different levels of priority to the applications running simultaneously on a station. Also called traffic prioritization.
private automatic branch exchange (PABX) See private branch exchange (PBX).
private branch exchange (PBX) A private telecommunications switching system allowing private local voice (and other voice-related services) switching over a network. (TIA)
program material The video and audio material that is broadcast over a cable system.
project log A written log of everything that happens on a project hour-by-hour, day-by-day, or item-by-item.
propagation The motion of waves through or along a medium.
propagation delay The time required for a signal to travel from one end of the transmission path to the other end. (TIA)
protector A device that prevents damage to lines or equipment by conducting hazardous high voltages or currents to ground. Most protectors come in assemblies containing fusible link stubs and the housing and circuitry for individual protector units.
protector bond A bond of a grounding conductor to a protector.
protector (cable) An outside plant protector that limits the voltage between the conductors and shield of a cable.
protector (ground conductor) A wire run from the ground lug on the protector to an approved ground via the shortest and straightest route.
protector (open wire) An outside plant protector that limits the voltage between open wire telecommunications conductors and ground.
protector unit A replaceable voltage-shunting device that is inserted on each cable pair in a protector assembly. The units come in a variety of types based on clamping voltages and reaction time.
protocol A set of rules and procedures governing the formatting of messages and the timing of their exchange between devices on a network covering addressing, transmitting, receiving, and verifying.
protocol stack A comprehensive set of specifications that define how network hardware and software interact at various levels to transfer messages between devices on a network (e.g., OSI Reference Model).
public opening An opening of request for quote responses (bids) at which all respondents may be present.
pull box (PB) A device to access a closed raceway used to facilitate placing of wire or cables.
pull cord A cord, string, wire, or tape placed within a cable pathway and used to pull wire and cable through the pathway.
pulled Call in or cash in of a bond because of a stated reason.
pull point Location where it is possible to physically access the cables to pull them.
pull strength The rated strength of the force of a cable that can be exerted on it during the pulling process. See also pull tension.
pull string A cord or wire placed within a cable pathway and used to pull wire and cable through the raceway. See also drag line and pull cord.
pull tension The pulling force that can be applied to a cable. (TIA)
pull wire See drag line and pull cord.
pWp See picowatts of noise power.

quadrature amplitude modulation (QAM) A means of encoding digital data that uses variations in signal amplitude and phase. QAM signals have 22N states, where each state encodes 2N bits. The encodings most commonly used include QAM-4, QAM-16, QAM-64, and QAM-256.
qualified Indicates compliance or accordance with specific standards or requirements.
qualified system A group of interacting, inter-related, or independent components forming a whole that indicates compliance or accordance with specific standards or requirements. See also qualified and system.
quality of service (QoS) 1. A commitment to performance, based on predefined service parameters. 2. A measure of the level of service provided on a network.
quarter-wave antenna A radio antenna that is one-fourth the size of the wavelength of the design frequency.

rabbet A cut or groove along or near the edge of a surface that allows another piece to fit into it to form a joint.
raceway Any enclosed channel designed for holding wires or cables. (TIA)
rack See cable rack.
rack unit (RU) A unit of measure of vertical space in an equipment rack. One rack unit is equal to 45 mm (1.75 in).
radio frequency (RF) The group of electromagnetic energy within the electromagnetic spectrum whose wavelengths are between the audio and the light range (usually between 535 kHz and 300 GHz).
radio frequency interference (RFI) The disruption of radio signal reception caused by any source which generates radio waves at the same frequency and along the same path as the desired wave. (Newton Telecommunications Dictionary)
radiating cable/leaking coaxial Comprises solid copper helical outer coaxial cable with solid copper inner and foam dielectric. The helical outer conductor has slots that allow ingress and egress of signals within a limited range of the cable. Coverage is omnidirectional perpendicular to the cable run for a cable suspended in space, but some
modification of the radiation pattern results from the structure to which the cable is attached. The main applications of this cable are indoor and underground coverage in large buildings, tunnels, and underground mines and facilities.
radome loss The sum of the ordinary insertion loss of the antenna signal passing through the radome wall plus the scattering loss off the radome panel framework blocking (shadowing) the antenna aperture.
random spacing Occurs where telephone cable is buried in the same trench with power conductors and no deliberate attempt is made to maintain a separation between the two systems.
Rayleigh scattering The deflection of light from the path it would follow if the refractive index were uniform or gradually graded. Caused primarily by micro defects, impurities, and molecular structure in the optical fiber.
receiver, optical An optoelectronic circuit that converts an optical signal to an electrical serial logic signal.
record copy drawing A drawing that is “hand marked” during the construction phase of a project to document actual construction as it deviates from the original design. Used as a record for updates to a design drawing to create a record drawing.
record drawing (as built) A plan, on paper, that graphically documents and illustrates the installed telecommunications infrastructure in a building, or portion thereof. (TIA)
redirector See shell.
reflection The abrupt change in direction of light as it travels from one material into a dissimilar material. See also Fresnel reflection.
reflector In a radio frequency antenna, one or more conducting elements or surfaces that reflect incident radiant energy.
refraction The angular change in direction of a beam of light at an interface between two dissimilar media or a medium whose refractive index is a continuous function of position (graded-index medium).
refractive index See index of refraction.
Registered Communications Distribution Designer (RCDD®) A designation for individuals who demonstrate expertise in the design, integration, and implementation of telecommunications (voice, data, video, audio, and other low-voltage control) transport systems and their related infrastructure components.
remote station A station that connects to the network over a telecommunications circuit.
See also local station and station.
repeater A device that regenerates a digital signal. A repeater receives a signal from one source, reads it, generates a completely new signal identical to the original, and transmits it to the next destination. Repeaters can be separate devices to boost long-haul transmissions or can be incorporated into other devices such as switches and routers.
request for information (RFI) A written request for clarification or information about the contract documents, products, or services offered. It may be issued from a supplier of products or services, or the customer may issue it.
request for interpretation (RFI) See request for information.
request for quotation (RFQ) A document that solicits quotes for projects or equipment and provides vendors with all the information necessary to prepare a quote.
requester See shell.
respondent A person or company that submits a proposal in response to a request for quote.
response due date The date by which a response to a request for quote must be received in order to be valid.
retainage A percentage of a total contract that is withheld from a contractor until the entire scope of work is completed.
retrofitting To modify systems that are already in service using parts made available after the time of original installation.
return loss A ratio, expressed in dB, of the power of the outgoing signal to the power of the reflected signal. When the termination (load) impedance does not match (equal) the value of the characteristic impedance of the transmission line, some of the signal energy is reflected back toward the source and is not delivered to the load; this signal loss contributes to the insertion loss of the transmission path, and is called return loss. (TIA)
reverberant sound Sound that is reflected from a surface (e.g., wall or floor) to the listener.
reversed pair A condition in which the conductors in a pair are terminated in the wrong sequence (i.e., tip connects to ring and ring connects to tip).
right-of-way (R/W) A route across public or private lands over (or under) which telecommunications facilities can be legally installed and maintained.
rise time Transmitters have bandwidth limitations because they take time to change from a low power state (logical 0) to a high power state (logical 1). This period is called the rise time.
riser cable See backbone cabling.
riser closet See telecommunications room.
rough-in 1. Cabling installed before walls are enclosed or finished. 2. Cabling installed in anticipation of future use or need. 3. The time in which a residential cabling installer runs the cable between the various termination points, the main task during this period being to complete all the work that is difficult to do once interior ceiling and wall materials are installed.
route loop diversity A type of loop diversity that assigns circuits along entirely different cable paths to a building.
router An internetworking device, operating at the Network layer of the Open Systems Interconnection model, used to direct packets from one network to another.

saddle A device for establishing the position of the raceway or raceways within the concrete relative to the screed line and for maintaining the spacing between the raceways. (TIA)
safety plan A plan prepared by a company and put in place before beginning any work operation, covering all safety issues likely to arise on a particular job site.
sag 1. A decrease in nominal root mean square voltage or current lasting 0.5 cycles up to one minute. 2. The difference in height between an aerial cable mounting and the height of the cable above the surface.
satellite closet See telecommunications room.
satellite room See telecommunications room.
SC connector See subscriber connector.
scalability The ability of a network to grow without degradation of quality.
scattering The deflection of light by small particles or inhomogeneities whose size is similar to or smaller than the wavelength of light. See also Rayleigh scattering and Mie scattering.
schematic diagram A structural or procedural diagram used in association with telecommunications and electrical systems.
schematic design A design phase that follows preliminary planning and scope development and occurs prior to design development. (This phase typically takes the design to about 30 percent.)
screened twisted-pair (ScTP) cable Cable made up of one or more pairs of twisted copper conductors with an overall foil shield and drain wire. The entire assembly is covered with an insulating sheath (cable jacket). Also called foil twisted-pair cable.
secondary power Power operating at less than 300 volts (V) to ground, typically 120/240 V or 277/480 V root mean square.
secondary test After acceptance testing, additional tests that are conducted to diagnose a problem or verify the cabling to additional requirements.
secondary voltage (supplemental/auxiliary) protector A secondary voltage protector installed in series with the indoor communications wire and cable between the primary
protector and the equipment. The secondary protector provides overcurrent protection that will safely fuse at currents less than the current-carrying capacity of the device that it is intended to protect.
sectional drawing Drawing as if a vertical cut was made through the materials indicating relationships, connections, and transitions.
SectionFormat™ A format that provides a uniform approach to organizing specifications text contained in a project manual by establishing a structure consisting of three primary parts.
security (network) Protection against unauthorized activities, generally requiring a combination of access controls, data integrity, and transaction confidentiality.
security and access control (SAC) Equipment associated with systems used to monitor and control devices (e.g., card readers, door alarms, and closed circuit television).
segmentation The process of dividing a LAN into multiple independent segments to improve overall data transfer rates.
Series 6 coaxial cable Having a center conductor measuring approximately 18 AWG [1.0 mm (0.039 in)], it supports similar applications as Series 11 coaxial cable; however, over a shorter distance due to increased insertion loss (attenuation) characteristics. Typically used for drop cabling.
Series 11 coaxial cable Having a center conductor measuring approximately 14 AWG [1.6 mm (0.063 in)], it supports similar applications as Series 6 coaxial cable; however, over a greater distance due to reduced insertion loss (attenuation) characteristics. Typically used for backbone cabling.
server A network device that combines hardware and software to provide and manage shared services and resources on the network.
service clearance The space encompassing the equipment, or unit, that is required to permit proper working room for operating, inspecting, and servicing equipment.
service entrance See entrance facility (telecommunications). (TIA)
service fitting An outlet box to house the connections for telecommunications at the user work area. See also insert. (TIA)
service loop A surplus of cable, typically located at or near the point of termination to facilitate potential future changes.
service provider (SP) The operator of any service (e.g., application programming interfaces) that furnishes telecommunications content (transmissions) delivered over access provider facilities. (TIA) See also access provider (AP).
setscrew coupling Couplings that are placed over the ends of conduit with little or no friction. Once the end of the conduit is seated into the coupling, two screws are tightened on the outside of the coupling, causing the coupling to become firmly attached to the conduit.
shallow room An enclosed space for housing cable terminations, cross-connect cabling, and telecommunications equipment.
shared tenant service (STS) Consolidates individual-line subscribers using a common premises switch.
sheath See cable sheath. (TIA)
sheath (cable) loop diversity A type of loop diversity that assigns circuits among different sheaths or cables.
shell A software-controlled interface between a user and an operating system. The shell software examines commands and user interaction for access to remote resources, processing the requests via the operating system.
shield A metallic layer (e.g., copper braids, metal foils, solid tubing) placed around a conductor or group of conductors. (TIA)
shielded enclosure cabinet A metal electronics cabinet constructed with welded seams and conductive gaskets on the doors that serve as an effective shield against electromagnetic radiation. (TIA)
shielded twisted-pair (STP) cable Cable made up of multiple twisted copper pairs with an additional metallic shield covering each individual pair. The entire structure is covered with an overall shield or braid and an insulating sheath (cable jacket).
shop drawing These drawings may be prepared by the contractor, subcontractor, or material/equipment supplier, and show how a particular aspect of the work is to be fabricated or installed.
short wavelength (SW) See wavelength.
signal encoding The conversion of data into a form suitable for transmission over a medium.
signaling The central information or supervisory information provided by a network to facilitate circuit setup and disconnection. One example of signaling is the process used to transfer a sequence of bits over a communications medium.
signal-to-noise ratio (SNR) The ratio between the amount of signal power at the receiver input and the detected noise in a given communications system, expressed in decibels.
simplex signaling A unidirectional signaling method in which data transfer can take place in only one direction, with no capabilities to change directions. See dual-duplex signaling, full-duplex signaling, and half-duplex signaling.
sine wave A sinusoidal wave that varies periodically from zero to a maximum, back through zero to a minimum, and back to zero.
singlemode optical fiber Optical fiber with a relatively small core diameter of 8–9 micron (micrometer) and a cladding diameter of 125 micron; lightwave propagation is restricted to a single path, or mode, in singlemode optical fiber.
single-point ground (SPG) terminal A ground connecting point for connecting communications equipment and raceways to the building’s grounding system.
sinusoid An oscillating, periodic signal that is completely described by three parameters—amplitude, frequency, and phase.
sky wave A radio wave that travels upward from the antenna. A sky wave may be reflected to Earth by the ionosphere, troposphere, or stratosphere.
slab See floor slab.
slab on grade Concrete floor placed directly on soil, without a basement or crawl space. (TIA)
sleeve An opening, usually circular, through the wall, ceiling, or floor to allow the passage of cables. (TIA)
slip sleeve An oversized conduit that moves easily along an inner conduit and covers a gap or missing part of the smaller conduit. (TIA)
slot An opening through a wall, floor, or ceiling, usually rectangular, to allow the passage of cables. (TIA)
small form factor (SFF) connector A connector that consists of two optical fibers secured in a plug approximately the size of an 8-position modular jack. An alternative type of optical fiber connector allowed under ANSI/TIA/EIA 568-B.3.
sneak current A foreign current flowing through terminal wiring and equipment that is driven by a voltage that is too low to cause the overvoltage protector to operate.
sneak current protection The use of devices to protect against sneak currents either by interrupting the current (sneak current fuses) or grounding the conductor (heat coils).
soft handoff A cellular signal that is controlled by multiple cells before disconnecting and being handed off from the previous controlling cell (make-before-break).
sound level meter Instrument used to measure actual pressure created by a sound.
sound pressure level (SPL) The actual air pressure created by a sound as measured by a sound level meter.
space (telecommunications) An area used for housing the installation and termination of telecommunications equipment and cable. (TIA)
space wave A radio wave that is not reflected back to earth and continues into outer space. These radio waves above 30 MHz have shorter wavelengths, which penetrate the ionosphere and continue on into outer space. Also called direct waves.
spade lug A U-shaped metal connector that is soldered or crimped to a wire, used for connection to a terminal post.
spine cable tray Open tray with a central rigid spine with cable support ribs along the length at 90-degree angles.
splice 1. A joining of conductors meant to be permanent. (TIA) 2. A device that joins conducting or transmitting media. See also straight splice.
splice case A metal or plastic housing with a semi-cylindrical cavity used in identical pairs to clamp around a cable splice to provide a closure.
splice closure A device used to protect a splice. (TIA) See also splice case.
splice (ground wire) A method where ground wire is extended by joining together two or more separate sections by fusing or mechanical connectors.
splice tray A container used to organize and protect fiber splices, as well as a means for storing fiber slack.
splicing The act of joining copper conductors or fiber strands.
split pair Transposition of two conductors of separate pairs.
splitter A network device that provides signals to a number of outputs, which are individually matched and isolated from each other. A passive device used to divide the signal into two or more outputs.
spool 1. A combination of hardware and software commonly used by print servers to redirect requests destined for a printer. 2. Cylindrical containers of cable. See cable reel. 3. A cylindrical guide, typically used for routing jumpers, cross-connects, and patch cords.
spread spectrum A radio transmission technology that distributes the transmitted signal over multiple frequencies within the assigned frequency band to increase the overall immunity of the signal to noise and prevent message interception.
standard A collection of requirements that encompass properties of components and systems that is intended to ensure an accepted degree of functionality and longevity. (ATIS)
standing wave ratio The ratio of the amplitude of a standing wave at an antinode to the amplitude at a node. A normalized measurement or calculation conducted in radio frequency systems useful for determining the amount of power reflected back to a source vs. that delivered to the load.
star coupler An optical component that allows emulation of a bus topology in an optical fiber system.
star topology network topologies in which services are distributed from or through a central point. (TIA)
station 1. A device used by an individual to access network services. 2. An input or output point in a communications system (e.g., telephone, computer, fire alarm station). See also local station and remote station.
station cord See work area cable (cord).
station equipment See customer premises equipment.
station fuse An overcurrent device used at the customer’s premises.
statistical time division multiplexing (STDM) An advanced version of time division multiplexing (TDM). Unlike TDM, the STDM method analyzes statistics related to the typical workload of each input device (e.g., printer, computer) and determines how much time each device should be allocated for data transmission on the
telecommunications circuit (e.g., T1 or T3 line).
step-index fiber An optical fiber, either multimode or singlemode, in which the core refractive index is uniform throughout so that a sharp step in refractive index occurs at the core-to-cladding interface.
stipulated sum See lump sum.
straight splice A splice in which one conductor or optical fiber strand is spliced from opposite directions.
strand 1. A single string of wire used to make up a larger wire or cable by twisting a number of strands together. Galvanized steel stranded cable is used as support strand and guy wire. 2. A single unit of optical fiber within a cable.
stroke factor The number of lightning strokes to ground per unit area for each thunderstorm day (obtained by statistical studies).
stub-up See conduit stub-up.
subduct See innerduct.
submittal Information, documentation, or samples that a contractor may be requested to submit to the design team for review and approval before the commencement of work.
subscriber connector (SC) The optical fiber SC (SCFOC/2.5) has a square front profile with push-pull latching mechanism maintaining the polarity of duplex cables.
substitution A replacement or alternation of material or process called for in the design documents.
supervisory control and data acquisition (SCADA) SCADA systems are used in industry and by public utilities (e.g., pipelines, electric utility grids) to monitor and control plant status and provide logging facilities that are often scattered over wide geographic areas. SCADA systems are highly configurable and traditionally use standard telephone lines to propagate their data. Public utilities are starting to utilize these systems for the
integration and transmission of voice, data, and security systems.
supplementary The way to provide additional conditions to a contract that may add, delete, or modify the general conditions.
support strand (messenger) A strength element used to carry the weight of the telecommunications cable. (TIA)
surety bond A bond that ensures a respondent (bidder) to a request for quote (RFQ) is sincerely interested in performing the project and has responded accurately to the RFQ specifications.
surface fitting Surface-mounted service fitting. See also service fitting.
surface transfer impedance The ratio of the conductor-to-shield voltage per unit length to the shield current. Surface transfer impedance is usually measured in milliohm/meter or ohm/foot.)
susceptibility (electromagnetic) The inability of a device, equipment, or system to resist an electromagnetic disturbance.
suspended ceiling A ceiling that creates an area or space between the ceiling material and the structure above. (TIA)
swell An increase in the nominal root mean square voltage or current lasting from 0.5 cycles to one minute.
switch 1. A network access device that provides a centralized point for LAN communications, media connections, and management activities where each switch port represents a separate communications channel. Sometimes referred to as a multiport bridge. See also bridge. 2. A voice communications device that utilizes switching
technology to establish and terminate calls.
switching 1. Networking protocol in which a station sends a message to a hub, which then routes the message to the specified destination station. 2. Establishing a direct signal path form one device to another. Establishing a direct signal path from one device to another.
synchronous communication See synchronous signaling.
synchronous optical network (SONET) A scalable transport technology designed to provide a uniform, consistent method of transferring data, by using an optical fiber transmission infrastructure.
synchronous signaling A form of signaling in which no start and stop bits are used. Each data character is coded as a string of bits and the sending and receiving devices are synchronized with each other, using a common clock. See also asynchronous signaling and isochronous signaling.
synchronous transmission Transfer of data using synchronous signaling.
system Includes a group of interacting, inter-related, or independent components forming a whole.

T0, T1, T2, T3, T4, and T5 drawings Telecommunications drawings that show site information (T0), building information (T1), serving zone information (T2), telecommunications rooms (T3), details (T4), and schedule/spreadsheets (T5).
tap 1. An electrical connection permitting signals to be transmitted onto or off a bus. 2. The linking between the bus and the drop cable that connects the workstation to the bus in 10BASE-5 Ethernet. 3. A device used on community antenna television cables for matching impedance or connecting service drops. See also bridged tap.
telecommunications Any transmission, emission, and reception of signs, signals, writings, images, and sounds; that is, information of any nature by cable, radio, optical, or other electromagnetic systems. (TIA)
telecommunications bonding backbone (TBB) A copper conductor used to connect the telecommunications main grounding busbar (TMGB) to the telecommunications grounding busbar (TGB) located on the floor farthest away. (TIA)
telecommunications bonding backbone interconnecting bonding conductor (TBBIBC) See grounding equalizer.
telecommunications closet (TC) See telecommunications room.
telecommunications enclosure (TE) 1. A case or housing for telecommunications equipment, cable terminations, and cross-connect cabling. (TIA). 2. A telecommunications space that differs from equipment rooms and entrance facilities in that this space is generally considered a floor-serving or tenant-serving (as opposed to building- or campusserving) space that provides a connection point between backbone and horizontal cabling.
telecommunications grounding busbar (TGB) A common point of connection for telecommunications system and equipment bonding to ground, and located in the telecommunications room or equipment room. (TIA)
Telecommunications Industry Association (TIA) An association that publishes telecommunications standards and other documents.
telecommunications main grounding busbar (TMGB) A busbar placed in a convenient and accessible location and bonded, by means of the bonding conductor for telecommunications, to the building service equipment (power) ground. (TIA)
telecommunications media See media (telecommunications) (TIA)
telecommunications outlet See outlet/connector (telecommunications). (TIA)
telecommunications outlet/connector Provides the means for the tenant to connect premises equipment. See also outlet/connector (telecommunications).
telecommunications room (TR) An enclosed architectural space for housing telecommunications equipment, cable terminations, and cross-connect cabling. (TIA)
telecommunications service entrance See entrance facility (telecommunications). (TIA)
Telecommunications Systems Bulletin (TSB) Document published by the Telecommunications Industry Association used to provide guidance for design methodologies or installation practices that pertain to telecommunications cabling systems. The next published edition of a related standard typically incorporates these bulletins.
telephone backboard An area used for the purpose of cable termination and crossconnection of telecommunications circuits. May be used for cross-connection or interconnection to active equipment or simply as a cross-connection of backbone cabling.
telephone test set A voice circuit-testing device used to identify circuits and perform diagnostics (e.g., butt set).
terminal (TERM) 1. A point at which information may enter or leave a telecommunications network. (TIA) 2. A device by means of which wires may be connected to each other. (TIA)
terminal emulation The process that enables a personal computer to operate as a terminal for connecting to a mainframe or minicomputer.
termination The ending of a transmission or transmission pathway.
termination hardware Considered to be obsolete. See also connecting hardware. (TIA)
terms and conditions (T&C) A section in a request for quote (RFQ) that defines the terms used in the RFQ and the conditions under which the work must be performed.
test hole A hole or group of holes dug along a proposed underground route to determine what utilities or other obstructions may be present.
tested Implies that a product or system has been evaluated against a set of metrics and has met a known set of criteria.
thin client A device similar to a personal computer with respect to processing power, memory capacity, and graphics capability but lacking removable storage devices.
threadless fitting A conduit connector or coupling that does not thread onto the end of the conduit. The compression ring style provides a weatherproof seal.
through penetration A continuous opening that passes through both surfaces of a firerated barrier. (TIA)
throughput The amount of data transferred between two points in a given amount of time.
thunderstorm day Any day thunder is heard at a specific observation point.
TIA/EIA Trade associations involved in developing telecommunications industry standards.
tie cable Any media type (e.g., balanced twisted pair or optical fiber cable) installed between any two cross-connect systems (e.g., main cross-connect [campus distributor] to horizontal cross-connect [floor distributor]) for the purpose of distributing telecommunications services either between buildings on a campus or between
telecommunications spaces (e.g., equipment room, telecommunications room, entrance
facility) within the same building. See also backbone.
tight buffer A type of cable construction where each fiber is coated with a protective thermoplastic coating to a diameter of 900 microns.
tight-buffered optical fiber cable Type of cable construction whereby each glass fiber is tightly buffered by a protective thermoplastic coating to a diameter of 900 microns. Increased buffering provides ease of handling and connectorization.
time division multiplexing (TDM) A transmission technique whereby several lowspeed channels are combined into a single high-speed channel for transmission. Each lowspeed channel is allocated a specific time position in the bit stream.
time domain reflectometer (TDR) A device that sends a signal down a cable, then measures the magnitude and amount of time required for the reflection of that signal to return. TDRs are used to measure the length of cables as well as locate cable faults.
token A Layer 2 frame containing access control information that is passed from device to device on a token ring, bus, or fiber distributed data interface network.
token passing An access control method that uses an electronic signal called a token.
topology The physical or logical arrangement of a telecommunications system. (TIA) See also logical topology and physical topology.
trade size Name given to materials to identify a nominal size.
traffic prioritization See prioritization.
transceiver 1. A radio transmitter and receiver combined into a single unit. 2. A device that acts as an interface between the network and the connected device.
transition point (TP) A location in the horizontal cabling where flat undercarpet cable connects to round cable. (TIA)
translational bridge A networking device capable of converting frame formats from one type to another prior to forwarding messages. Only operates on the logical link control sublayer of the Data Link layer.
transmission The movement of information as electrical or optical signals from one point to another via a medium.
transmission media The physical carriers of signal energy radiation (e.g., copper, optical fiber, air). See also media (telecommunications).
transmission medium See medium.
transmitter (TX) Signaling source.
transmitter combiners A device that allows several transmitters operating in the same frequency range to use a single transmission line and antenna.
transmitter (TX [(optical]) An electronic package that converts an electrical signal to an optical signal.
transparent mode A form of remote access where the remote station accesses LAN resources through a remote access server and operates in the same manner as a local station, eliminating the need for a local station.
transposed pairs When two pairs of conductors are terminated in each other’s location.
tray See cable tray.
trench A furrow dug into the earth for the placement of direct-buried cable, or for the installation of conduit ducts.
trench duct An interior or exterior trough embedded in concrete that has removable cover plates level with the top of the surrounding surface. See also header duct.
trough (cable) A pathway for the containment and protection of cable, typically provided with a removable cover.
trunk cable Refers to the main distribution cable. A typical trunk cable begins at the headend and terminates at the outermost feeder cable.
trunk distribution and feeder Rigid coaxial cable, typically used for backbone cabling.
trunking See link aggregation.
tunnel A virtual private network connection through the Internet.
twisted-pair Two individually insulated copper wires physically twisted together to form a balanced pair.
twisted-pair cable A multiconductor cable comprising two or more copper conductors twisted in a manner designed to cancel electrical interference. Also called balanced twisted-pair cable.
twisted-pair physical medium dependent (TP-PMD) A network protocol that allows for 100 Mb/s transmission. Another name for ANSI X3.263 standard and copper distributed data interface.
two-level duct An underfloor raceway system installed with the header raceways and the distribution raceways on two different planes. (TIA)

ultraviolet (UV) light The portion of the electromagnetic spectrum in which the longest wavelength is just below the visible spectrum, extending from approximately 10 nm to approximately 400 nm.
underfloor duct system A network of metal raceways embedded in concrete, which facilitates the distribution of horizontal cables (e.g., between telecommunications rooms or telecommunications enclosures and work areas).
underfloor raceway A pathway placed within the floor and from which wires and cables emerge to a specific floor area. (TIA)
underground cable A telecommunications cable designed to be installed under the surface of the earth in a trough or duct that isolates the cable from direct contact with the soil. (TIA) Contrast with direct-buried cable.
underground facilities Cables placed in subsurface conduits, using maintenance holes, handholes, and pull boxes.
Underwriters Laboratories Inc.® (UL®) A United States-based independent testing laboratory that sets safety tests and standards.
Underwriters Laboratories of (ULC) A Canadian-based independent testing laboratory that sets safety tests and standards.
unequal splitter A device that asymmetrically splits a radio frequency signal between two outputs while maintaining dc continuity between all ports.
unidirectional antenna An antenna characterized by a very narrow focus and an extended reach. See directional antenna and omnidirectional antenna.
UniFormat™ A document produced by the Constructions Specifications Institute (CSI) that is a classification system used to organize preliminary project descriptions, preliminary cost estimates, and drawings that detail filing.
unigrounded power system A power system where only one point, usually the midpoint, of the supply transformer bank is grounded. The neutral conductor may or may not be carried along with the phase wires.
uninterruptible power supply (UPS) A device that is inserted between a primary power source and the primary power input of equipment to be protected to eliminate the effects of transient anomalies or temporary outages.
uplink 1. Signals transmitted from ground stations to satellites. 2. In demand priority access method, the communications channel between a connected end node and a repeater, or between a repeater and a higher-level repeater.
utility column An enclosed pathway extending from the ceiling to furniture or to the floor that forms a pathway for electrical wiring, telecommunications cable, or both. (TIA)
utility pole A customer-owned outside plant pole owned by a private or municipal utility. See also pole.

value engineering An effort to examine and weigh the initial cost; evaluate the maintenance expense and ultimate worth of certain materials, components, and systems; and assess performance at the lowest price consistent with the project criteria during the design development/preliminary design phase.
valve-regulated lead-acid (VRLA) cell A battery cell that is regulated by a pressure relief valve and does not allow for the adding of water. Also called sealed or maintenancefree cells.
variable air volume (VAV) A self-contained heating, ventilating, and air-conditioning (HVAC) unit that uses a built-in microprocessor-based controller to control environmental air to a specific zone via a damper. The unit is placed near the end of a HVAC duct and can also monitor temperature inputs from local sensors.
varistor An electrical component whose resistance depends on the applied voltage or current.
vault A telecommunications space, typically subterranean, located within or between buildings and used for the distribution, splicing, and termination of cabling. These spaces may be established as a maintenance hole in campus environments or they may include active equipment in addition to passive cabling such as in a controlled environment vault.
ventilated channel Channel section with a one-piece bottom no more than 152 mm (6 in) wide.
ventilated trough A ventilated bottom with side rails.
virgin plywood New or unused plywood.
virtual circuit (VC) A communications path through an internetwork that appears to be a dedicated circuit between two network devices.
virtual LAN (VLAN) A technique made possible by switching technologies that permits the logical grouping of any number of network devices into one or more subnetworks to improve traffic management and/or security.
virtual private network (VPN) A combination of hardware and software technologies designed to enable secure passage of organizational network traffic over the Internet. See tunnel.
voice over Internet protocol (VoIP) A system in which voice signals are converted to packets and transmitted over a network using Transmission Control Protocol/Internet Protocol).
volt (V) A unit of electromotive force or potential difference that will cause a current of one ampere to flow through a resistance of one ohm.
voltage gradient The change in voltage differential per unit distance. See electric field strength.
voltage standing wave ratio (VSWR) The ratio of the maximum to the minimum voltage in the standing wave pattern that appears along a transmission line.
volt-ohmmeter (VOM) An instrument used to measure electrical characteristics. See multimeter.

waveguide A device used to direct radio frequency transmissions or light waves. A waveguide in radio systems normally consists of a hollow metallic conductor, usually rectangular, elliptical, or circular in cross section. In lightwave applications, a waveguide is normally small prisms or optical fibers.
wavelength The distance between two points in the same phase in consecutive cycles measured in the direction of propagation.
wavelength division multiplexing (WDM) Developed to increase the informationcarrying capacity of optical fiber transmission systems. This technique modulates a series of data streams using a different wavelength of light for each stream and simultaneously transports the multiple wavelengths over a single optical fiber.
waveshape (lightning) The numerical method of describing a voltage surge wave in terms of rise time vs.decay time (e.g., 1 x 50 or 10 x 100). The first number represents the rise time of the surge in microseconds from zero to peak surge value. The second number represents the subsequent surge decay time to 50 percent of the peak surge value from the beginning of the surge.
Web Used as a noun, it is shorthand for the World Wide Web (www) services found on the Internet.
wide area internetworking See wide area network.
wide area network (WAN) A data communications system that uses telecommunications circuits to link LANs that are distributed over large geographic distances.
wire An individually insulated solid or stranded metallic conductor. (TIA)
wire map Pin to pin termination and continuity of each individual continuity of each individual conductor. The wire map indicates continuity to the remote end, shorts between two or more conductors reversed pairs, split pairs, transposed pairs, and any other miswiring.
wiring See cabling.
wiring closet See telecommunications room.
wireless LAN gateway A device that provides functions similar to a wireless LAN switch but with additional administrative features.
wireway (WW) A supported pathway for cables.
wireless LAN gateway A device that provides functions similar to a wireless LAN switch but with additional administrative features.
work area (work station) A building space where the occupants interact with telecommunications terminal equipment. (TIA)
work area cable (cord) A cable connecting the telecommunications outlet/connector to the terminal equipment. (TIA)
work area outlet A connecting device for termination of horizontal media. See telecommunications outlet/connector.

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Old 01-04-2017 - Glossary and Definitions - Networking Computer Systems - Computer Networking Systems - Genaral - Voltage Talk forum
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Default Re: Glossary and Definitions - Networking Computer Systems

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