110 Connector

Insulation displacement connector (IDC) used in modular jacks, patch panels and cross connects.


This IEEE standard defines a Gigabit Ethernet local area network running 1000Mbps base band over unshielded twisted-pair cabling. Throughput over 10Base-T is improved by decreasing bit latency periods and increasing packet speeds.


This IEEE standard defines an Ethernet local area network running 100Mbps base band over unshielded twisted-pair cabling. Throughput over 10Base-T is improved by decreasing bit latency periods and increasing packet speeds.


This IEEE standard defines an Ethernet local area network running 10Mbps base band over unshielded twisted pair cabling, typically associated with Category 5.


This proposed IEEE standard defines 10 Gigabit Ethernet running 10GMbps over unshielded twisted-pair cabling. Positioned as high speed technology to support Metropolitan Area Networks and other high-demand applications.

66 Block

Cross connect system.

802.11 a/b/g

IEEE standards for wireless LANs. An 802.11a/b/g compatible Wireless Access Point works interchangeably with all three (802.11a, 802.11b, and 802.11g).


See Far End Cross Talk.


See Near End Cross Talk.


Alien crosstalk (AXT) is electromagnetic noise that can occur in a cable run alongside other signal-carrying cables. The term "alien" arises from the fact that this form of crosstalk occurs between different cables in a group or bundle, rather than between individual wires or circuits within a single cable.


Refers to a plywood or metal panel mounted on the wall of a telecom closet to mount the cross connect. Backbone Wiring The physical/electrical interconnections between telecommunications closets and equipment rooms. Cross-connect hardware and cabling in the Main and Intermediate Cross-Connects are considered part of the backbone wiring.


A transformer used to attach co-axial or twinaxial equipment to twistedpair cabling.


The difference between the highest and the lowest frequencies of a transmission channel (path for information transmission). Identifies the amount of data that can be sent through a given channel. Measured in Hertz (Hz); higher bandwidth numbers mean higher data capacity. Bend Radius (Fiber) Radius of curvature that a fiber can bend without breaking. Also see Cable Bend Radius..


(Building Industry Consulting Service International) BICSI is a non-profit professional association, for the promotion of telecom industry standards.


A bayonet style co-axial connector.

Bit Error Rate (BER)

In digital applications, the percentage of bits received in error to the total number of bits received. Usually expressed as a number to the power of 10. For example 10 to the fifth power means that one in every 100,000 bits transmitted will be wrong.

Cable Assembly

A fixed length of cable with connectors installed on both ends. Sometimes called a patch cord, patch cable or jumper.

Cable Bend Radius

The amount of bend that can occur before a cable may sustain damage or increased attenuation.

Category 3, CAT 3

A category of performance for inside wire and cable systems. Commonly used for voice applications and data to 10Mbps. Defined by FCC Part 68, ANSI/EIA/TIA-568, TIA TSB-36 and TIA TSB-40.

Category 5, CAT 5

A category of performance for inside wire and cable systems. Used in support of voice and data applications requiring a carrier frequency of up to 100 MHz. Defined by FCC Part 68, EIA/TIA-568, TIA TSB-36 and TIA TSB-40.

Category 5e (Enhanced), CAT 5e

A category of performance for inside wire and cable. Used in support of signaling rates of up to 100MHz over distances of up to 100 meters. Calls for tighter twists, electrical balancing between pairs and fewer cable anomalies. CAT 5e is intended to support 100Base-T, ATM and Gigabit Ethernet.

Category 6, CAT 6

A cable standard for Unshielded Twisted Pair (UTP) supporting signaling rates up to 250 MHz. Applications include 1000Base-T, ATM, Gigabit Ethernet and applications under development. Category 6 Augmented, CAT 6A Also referred to as 10G or 10Gigabit Ethernet. A cable standard for Unshielded Twisted Pair (UTP) supporting signaling rates up to 500 MHz. Applications include 10GBase-T, ATM, 10 Gigabit Ethernet, VoIP, and applications under development. Category of Performance Cabling and cabling component standard adopted by the telecommunications industry.


The entire horizontal cabling system. Everything between the computer and the LAN hub in the telecom closet, excluding the equipment connections.

Co-axial Cable

A cable composed of an insulated central conducting wire wrapped in another cylindrical conductor (the shield). The whole thing is usually wrapped in another insulating layer and an outer protective layer. A co-axial cable has great capacity to carry vast quantities of information.


A wiring device that meets all characteristics of a standard is said to be in compliance with that standard.


Any substance, usually a wire or cable that can carry an electrical current.

Connecting Block

Also called a terminal block, punch-down block, quick-connect block, or cross-connect block, this plastic block contains metal wiring terminals to establish connections from one group of wires to another. Usually each wire can be connected to several other wires in a bus or common arrangement. There are several types of connecting blocks: 66 clip, BIX, Krone, 110, etc. A connecting block has insulation displacement connections (IDCs), which means you don't have to remove insulation from around the wire conductor before you “punch it down” (terminate it).


A device that connects wires or fibers in cable to equipment or other wires or fibers. Wire and optical connectors most often join transmission media to equipment or cross connects. Connectors are sometimes referred to as jacks, but though all jacks are connectors, not all connectors are jacks. Consolidation Point An interconnect device that allows the horizontal cable to be split into two parts. Used for zone cabling.


Distribution system equipment used to terminate and administer communication circuits. In a wire cross-connect, jumper wires or patch cords are used to make circuit connections. In an optical cross-connect, fiber patch cords are used. The cross-connect is located in an equipment room, riser closet, or satellite closet. The Professional's Choice.


See Near-End Crosstalk.

Daisy Chain

In telecommunications, a wiring method where each telephone jack in a building is wired in series from the previous jack. Daisy chain is NOT the preferred wiring method, since a break in the wiring would disable all jacks “downstream” from the break. See also Home Run.

Data Center

A data center is a facility used for housing a large amount of electronic equipment, typically servers, computers, and communications equipment. Data centers are designed to assure that the servers and the data housed on them are protected from environmental hazards and security breaches. Data centers can be private, serving a single company or a public “utility” serving a variety of companies.

Data Rate

The speed, measured in bits per second, that a particular network transmits data.

db (Decibel)

A dB is a unit of measure of signal strength, usually the relation between a transmitted signal and a standard signal source. Every 3dB equals 50% of signal strength, so therefore a 6dB loss is a loss of 75% of total signal strength.

Delay Skew

The difference in propagation delay between the slowest and fastest pairs in a cable or system.

Demarcation Point

The point of interconnection between telephone company terminal equipment and your building wiring. The protective apparatus or wiring at a subscriber's premises.


As distinguished from equipment. In telecommunications, a “device” is the physical interconnection outlet.Equipment (a computer, phone, fax machine, etc.) then plugs into the device. See also Equipment and Plug.


Refers to the horizontal cabling for one work area.


Electronic Industries Alliance. A trade organization of manufacturers which set standards for use of its member companies. Many associations fall under the umbrella of EIA, though it has recently been absorbed by the TIA, or Telecommunications Industry Association. See or


Electronics Industry Association/ Telecommunications Industry Association.


Equal Level Far End Crosstalk. A measure of FEXT which accounts for the attenuation of the cabling system.

Electromagnetic Interference (EMI)

The interference in signal transmission or reception caused by the radiation of electrical and magnetic fields.


As distinguished from Device. Telecom equipment (computers, phones, faxes, etc.) plugs into telecommunications outlets or devices. See also Device.


Type of local area network used for connecting computers, printers, workstations, terminals, etc. within the same building. Ethernet is a physical link and data link protocol that operates over twisted pair wire and over co-axial cable at speeds up to 10Mbps. Far End Crosstalk (FEXT) An electromagnetic interference (EMI), a type of crosstalk, introduced on UTP by close-by wires, usually running in parallel with the FEXT induced wire. "Far End" refers to the inductance of EMI in the end further from the end being measured on the alternate wire in a pair.

F Connector

A common co-axial connector used for video applications (CATV).


Far End Crosstalk. Unwanted noise coupled onto a receive pair from a transmit pair at the far end of the system.

Fiber Optics

A technology in which light beams are used to transport digital information from one point to another via thin filaments of glass. Benefits include the ability to transmit enormous amounts of data over long distance, high bandwidth, relatively low cost, low power consumption, small space needs, total insensitivity to electromagnetic interference, and excellent security control.


When used to describe data transfer rates, it refers to 10 to the 9th power (1,000,000,000) bits. Gigabit Ethernet, abbreviated GbE,supports data transfer rates of 1 Gigabit (1,000 megabits) per second. The first Gigabit Ethernet standard (802.3z) was ratified by the IEEE 802.3 Committee in 1998.

Gigabit Ethernet

The newest and fastest version of Ethernet. Data rate is 1000 Mbps or 1 Gigabit per second. Headroom (Also called Overhead or Margin) The number of decibels by which a system exceeds the minimum defined requirements. The benefit of headroom is that it reduces the bit error rate (BER), and provides a performance 'safety net' to help ensure that current and future high speed applications will run at peak accuracy, efficiency and throughput.

Home Run

Telephone system wiring where the individual cables run from each telephone directly back to the central switching equipment. Home run cabling can be thought of as “star” cabling. Every cable radiates out from the central equipment. See also Star Wiring, Daisy Chain. Horizontal Cabling Includes the work area outlet, distribution cable and connecting hardware in the telecom closet.


Network device, usually in the telecom closet, that stations connect to.

IDC (Insulation Displacement Connection)

A type of wire termination where wire is “punched down” into a metal holder which cuts into the insulation wire and makes contact with the conductor, causing the electrical connection to be made.

IDF (Intermediate Distribution Frame)

A metal rack designed to connect cables located in an equipment room or closet. Consists of components that provide the connection between inter-building cabling and the intra-building cabling, i.e. between the Main Distribution Frame (MDF) and individual telephone wiring. There's usually a permanent, large cable running between the MDF and IDF. The changes in wiring are done at the IDF.


Institute of Electrical and Electronics Engineers. Develops Local Area Network standards and Metropolitan Area Network standards.


The total opposition (i.e. resistance and reactance) a circuit offers to the flow of alternating current. It is measured in ohms, and the lower the ohmic value, the better the quality of the conductor.

Insertion Loss

The difference in the amount of power received before and after something is inserted into the circuit. In optical fiber, insertion loss is the optical power loss due to all causes, usually expressed as decibel/kilometer.


A circuit administration point, other than a cross- connect or an information outlet, that provides capability for routing and rerouting circuits. It does not use patch cords or jumper wires, and typically is a jack-and-plug device used in smaller distribution arrangements or that connects circuits in large cables to those in smaller cables.


The ability of systems or components to provide services to and accept services from other systems or units. Therefore, the services are able to operate effectively together. Interoperable structured cabling systems allow the user their choice of connectivity components which will effectively operate in conjunction with their choice of cable.


Usually unjacketed twisted pair wire used to make a cross connection.


A data rate. Kilobits, or thousands of bits, per second.


Local Area Network. A short distance network (typically within a building or campus) used to link together computers and peripheral devices (such as printers) under some form of standard control. LC (Latching Connector) A miniaturized version of the fiber-optic SC connector. It looks just like the SC, but is half the size with a 1.25 mm ferrule instead of 2.5 mm.

Laser Optimized

Laser-optimized (50 micron, multimode) fiber: Laser-optimized multimode fiber cable allows the use of lower cost laser light sources, so-called VCSELs (Vertical Cavity Surface Emitting Lasers) to achieve speeds and distances previously only possible through a more expensive single mode fiber laser. TIA-568-C outlines the specification for OM3 grade fiber as an 850-mn, laser- optimized, 50 micron cabled fiber for 10GbE distances out to 300 meters. TIA-598-C standard adopted the aqua colored jacket to correspond to performance requirements.


The part of the horizontal cabling system between the work area outlet and the telecom closet termination.


Megabits Per Second. One million bits per second. (Different from MBps, or a million bytes per second.)


Main Distribution Frame. A wiring arrangement which connects the telephone lines coming from outside on one side and the internal lines on the other. A main distribution frame may also carry protective devices as well as function as a central testing point.


Megahertz. Millions of cycles (Hertz) per second. A frequency or frequency range (Bandwidth) through which a cabling system is specified.

Modular Jack

The standard female connector for twisted pair cable.

Modular Plug

The standard male connector for twisted pair cable.


A small form factor fiber optic connector that is defined by its high density footprint and RJ47 locking mechanism.


Optical fiber with either 50 micron or 62.5 micron core size, designed to allow light to carry multiple signals distinguished by frequency or phase, at the same time. Can be used with LED or LASER light sources. Contrasts with single- mode. Common in Local Area Networks.

Multi-user outlet

A work area outlet designed to support multiple users. Also called multi-user telecommunications outlet assembly. The Professional's Choice.

Near End Crosstalk

(NEXT) is an electromagnetic interference (EMI), also known as crosstalk, introduced on UTP by close by wires, usually running in parallel with the NEXT induced wire. "Near End" refers to the inductance of EMI in the end closer to the end being measured on the alternate wire in a pair.


A network ties things such as communications or computer equipment together. Computer networks connect computers and computer- related things— terminals, printers, modems, door entry sensors, temperature monitors, etc. Local Area Networks (LANs) to connect computer equipment within a building or campus. Wide area networks extend beyond metropolitan areas.


Network Interface Card. Allows a PC to attach to a network.


A device connected to a network.


A telecommunications outlet is a single-piece cable termination assembly (typically on the floor or in the wall), containing one or more modular telecom jacks. Such jacks might be RJs, co-axial terminators, fiber optic couplers, etc. See also Device and Equipment.

Patch Cord

A cable assembly with a plug on each end, used to make a cross connection.

Patch Panel

A rack-mountable panel (usually 19” wide) containing connecting hardware. Used to patch between groups of cables and equipment.


Private Branch Exchange. The premises telephone switch. Handles all telecom functions.


Compare with Compliance. A device can exhibit performance characteristics without being compliant to an industry standard.

Plenum Cable

Cable specifically designed for use in a plenum (the space above a suspended ceiling used to circulate air back to the heating or cooling system in a building).


Power Over Ethernet technology describes any system to transmit electrical power, along with data, to remote devices over standard twisted- pair cable in an Ethernet network. This technology is useful for powering IP telephones, wireless LAN access points, webcams, Ethernet hubs, computers, and other appliances where it would be inconvenient or infeasible to supply power separately.


A term describing positive and negative sides of an electrical circuit. Positive and negative wires must be wired correctly to support touchtone phones and video. The Professional's Choice.


Plain Old Telephone Service. The basic service supplying standard single line telephones, telephone lines and access to the public switched network with no added features such as call waiting or forwarding.

Power Sum

A test method for four pair cable whereby the mathematical sum of pair-to-pair crosstalk from three pairs to one pair is measured. Premises Wiring System The entire wiring system on the user's premises, especially the supporting wiring that connects the communications outlets to the network inter-face jack.

Propogation Delay

The amount of time it takes a signal to travel through a cable or system.


See Power sum and ELFEXT.


See Power sum and NEXT.


Refers to the use of an impact tool that enables installers to make efficient IDC style connections.

Rack Mount

Fiber Enclosure


Used to mount patch panels, enclosures and equipment in the telecom closet. Usually 19”wide by 7' high.


The RCDD (Registered Communications Distribution Designer) title is a professional rating granted by BICSI (the Building Industry Consulting Service International). RCDDs have demonstrated a superior level of knowledge of the telecommunications wiring industry and associated disciplines.

Return Loss

A measure of the similarity of the impedance of a transmission line and the impedance at its terminations. It is a ratio, expressed in decibels, of the power of the outgoing signal to the power of the signal reflected back.


Backbone cabling connecting telecom closets situated vertically on separate floors.

RJ (Registered Jack)

RJs are telephone and data jacks registered with the FCC. Numbers, like RJ-11, RJ-45, etc. are widely misused in the telecommunications industry. A much more precise way to identify a jack is to specify the number of positions (width of opening) and number of conductors. Example: “8-position, 8-conductor jack” or “6- position, 4-conductor jack”.


A wiring pattern for 6-position modular jacks. Used to refer to the jacks themselves.


A wiring pattern for a 25-pair connector.


A wiring pattern for 8-position modular jacks. Used to refer to the jacks themselves. RoHS (Restriction of Hazardous Substances) European Directive 2002/95/EC requires specific limitations of six substances. Visit for more details.

SC (Stick and Click)

An SC fiber optic cable connector uses a push- pull connector similar to common audio and video plugs and sockets.

Single Mode

Optical fiber with an 8.3-9.5 micron core size, optimized for LASER light sources which transmit only one mode or path of light. This eliminates modal dispersion, the main limitation to bandwidth. Typical in long-haul networks and outside plant applications due to increased bandwidth.

ST (Stick and Turn)

A fiber-optic cable connector that uses a half-twist bayonet type of lock to keep the connection secure. ST connector was originated by AT&T Bell laboratories for use in premises wiring of buildings and other applications. It was the first de facto standard connector for most commercial wiring.


Shielded Twisted Pair. 2-pair 150 ohm shielded cable.


A type of network hub. Provides higher bandwidth than shared hubs.

T568A & T568B

The two standard wiring patterns for 8-position modular jacks.


Short for telecommunications or Telephone Company.

Telco Connector

Refers to a 25-pair connector.

Telecom Closet

The area of the building that houses the termination of the horizontal cabling.


IEEE 10BASE5. 10 Mbps Ethernet on thick co- axial cable.


IEEE 10BASE2. 10 Mbps Ethernet on thin (RG58) co-axial cable.


A standard for digital transmission in North America. A digital transmission link with a capacity of 1.544 Mbps (1,544,000 bits per second.) T1 lines are used for connecting networks across remote distances. Bridges and routers are used to connect LANs over T1 networks.


Telecommunications Industry Association. A trade organization of manufacturers which sets standards for use of its member companies. Formerly fell under the umbrella of EIA, (Electronic Industries Alliance). See


Telecommunications Industry Association / Electronic Industries Alliance.

Twisted Pair

Two insulated copper wires twisted around each other to reduce induction (thus interference) from one wire to the other. The twists, or lays, are varied in length to reduce the potential for signal interference between pairs.Several sets of twisted pair wires may be enclosed in a single cable. In cables greater than 25 pairs, the twisted pairs are grouped and bound together.


Unshielded Twisted Pair. See Twisted Pair.


Voice over Internet Protocol allows voice calls to be encoded and transmitted over the data network. Benefits are cost-savings, the ease of managing just one network, and lots of new services including integrated messaging, voice emails, number portability, and phone account management via Internet. The Professional's Choice.


Wide Area Network- a public voice or data network that extends beyond the metropolitan area.

Work Area

Where the users' communications equipment resides. The part of the cabling system between the outlet and the equipment.


The working area in a building required by one telecommunications user. Industry standards call for one voice drop and one data drop for each workstation. The voice drop is one 4-pair unshielded twisted pair (UTP). The data drop may be 100. 4-pair UTP, 150. 2-pair shielded twisted pair (STP), or optical fiber.

Zone Cabling

An architectural concept which splits the horizontal cabling into two sections. Eliminates the need to replace the entire horizontal cable in adds, moves and changes.