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A glossary of terms and abbreviations for open office cabling
These are the terms, definitions, and abbreviations you will hear regarding telecommunications cabling in buildings. This document focuses on those things that directly relate or interconnect with the more commonly used modular zone telecommunications cabling.

Backbone Cabling - The cabling that distributes voice and data services between the equipment room, telecommunications closets, and between buildings. See 'Horizontal Cabling.'

Categories (i.e. Category 5, 5 enhanced, 6, etc.) - Categories in this contest were established by the EIA/TIA (see EIA/TIA) to identify the performance levels of copper communications cabling. CAT 3 was designed for use with 10Base-T. CAT 5 was designed for use with 100Base-Tx, and the most recently passed CAT 5 Enhanced standards (CAT 5 E) were designed for use with 1000Base-T (gigabit). The Category 6 standards, as of this writing, are only in the proposal stage and not quite yet available. It is anticipated that the CAT 6 standards will be approved by early 2001. Category 5e is the de facto standard today.

Consolidation Point - A point of connect and disconnect now allowed in the open office between the telecommunications outlet and the telecommunications closet. Approved as part of the EIA/TIA standard under Technical Systems Bulletin 75 (TSB75).

Datacomm Contractor - The industry jargon for a data communications contractor, a firm that specializes in installing structured voice/data cabling systems in buildings. These firms are used on new installation and major renovations and typically do detailed testing, supplying the end-user with test results and certifications.

Electronic Industries Association/Telecommunications Industries Association (EIA/TIA) - Standards organizations that publish the specifications and test procedures for telecommunications cabling in a building. The current standard for voice/data cabling performance is EIA/TIA 568-A. This is almost universally accepted as the standard for the installation of voice and data cabling.

Equipment Room - A centralized space for telecommunications equipment that serves the occupants of the building. Equipment housed herein is considered distinct from a telecommunications closet (wiring closet) because of its nature or the complexity of the equipment.

Feeder Cable - This is the generic term for the cabling from the wiring closet out to another wiring closet or to the Consolidation Point when a zone solution is implemented. Feeder cable is terminated in wiring closets, and on the back of the Consolidation Point modules by the datacom contractor during the initial installation.

Fiber Optics - Light transmission through optical fibers for communications or signaling.

Horizontal Cabling - The cabling between the telecommunications outlet in the work area, and the Horizontal Cross-Connect (HC) in the telecommunications closet. The maximum allowed distance for this 'Link' is 90 meters for data cabling.

Intermediate Cross-Connect (IC) - A cross-connect between the main cross-connect (usually in the equipment room) and the horizontal cross-connect (usually in the telecommunications closet).

Horizontal Cross-Connect - Usually found in the telecommunications closet (wiring closet), it typically connects the backbone cabling to the horizontal cabling.

Local Area Network (LAN) - Computers, cabling and networking software forming a computer network in a specific area of a building.

Main Cross-Connect (MC) - The cross-connect in the main equipment room for connecting entrance cables, backbone cables, and equipment cables.

Main Telecommunications Closet (MC) - If a building has only one Telecommunications Closet (TC), it is called the Main Telecommunications Closet. If a building has more than one TC, then all of the backbone cabling from the rest of the TC's will terminate in one TC. The TC where all the backbone cabling terminates is known as the MC. Also known as a 'wiring closet,' the Main Telecommunications Closet is an enclosed space for housing telecommunications equipment, cable terminations, and cross-connects. The closet is also the recognized cross-connect between the backbone cable and horizontal cabling. The requirement is a minimum of one MC per any given building.

Megabits - The data rate, or rate of data transfer in a communications cable. Not used to specify performance in cabling under the standards. Do not confuse with Megahertz, which is used to specify the carrying capacity of a structured cabling system in the standard.

Megahertz (MHz) - A unit of frequency measurement that is equal to one million hertz. Used to measure the bandwidth, or carrying capacity of a cable.

Micron - A term for micrometer (one-millionth of a meter). Used in defining fiber cable diameter.

Modular Cable Assembly - Term for 10, 30 and 50-foot cable assemblies with a modular plug on one end that goes into a port on the Consolidation Point, and a jack on the other that snaps into a furniture faceplate to provide the telecommunications outlet for the user. These can be unshielded twisted pair (UTP), four-pair solid wire (not stranded) copper cables, or one-pair multimode fiber optic cables that perform the same voice or data function.

Modular Jack - A female connector (typically eight-position for data) that has become the standard interface for four-pair UTP copper cable. Also known as an RJ45 connector. This is found on the user-side ports and on the end of Modular Cable Assemblies. There are (unfortunately) two slightly different wiring patterns for this connector - T568A and T568B, and customers across the continent use one or the other. They cannot be mixed, requiring a set of Modular Cable Assemblies for each wiring pattern.

Modular Plug - A telephone-style male connector plug ( typically eight-position for data) with a latch that mates with the modular connector. This is the standard plug interface for copper UTP cabling. This plug is used at the end of the modular cables to plug into the modular jack connectors.

Multi-Mode Fibers - Optical glass fiber in which light travels in multiple modes. Typical core and cladding sizes (diameter) in microns are 50/125 and 62.5/ 125. Multi-mode fiber is the standard for horizontal cabling and LAN backbone cabling.

MT-RJ Fiber Optic Cabling - You will see this term as a modular fiber solution based on the small form-factor fiber optic connector known as the MT-RJ. This connector reduces the size of a fiber connector interface into something that will fit into the same faceplate hole size as the copper RJ45 connector. MT-RJ has reduced the complexity, cost, and size of fiber optic cabling, paving the way for its use all the way to the user outlet.

Patch Cable/Patch Cords - This is the industry term for the copper cable that makes the transition from the cross-connect in the wiring closet to the active equipment. It is also used to connect the workstation in the office to the telecommunications outlet in the panel or the wall. This cable is usually stranded wire and has an eight-position modular plug on each end. They can be purchased in a variety of lengths and colors, and can even be custom fitted and field engineered to specific lengths.

Pathway - A facility for the placement of telecommunications cabling in a building or furniture.

PVC - The abbreviation for polyvinyl chloride, a material used in manufacturing jacketing material for voice/data cabling.

RCDD (Registered Communications Distribution Designer) - Industry accepted designation for a person qualified by BICSI (the Building Industry Consulting Service International) to design or consult regarding telecommunications cabling systems. Information Technology (IT) managers typically expect the design of their cabling to be done or certified by an RCDD.

Structured Cabling - A communications cabling system in a building that is planned and installed as a complete entity to provide certain levels of functionality and performance.

Technical Systems Bulletin (TSB) 75 - When the EIA/TIA 568 standard is revised, Technical Systems Bulletins are published as additions. TSB 75 was approved in late 1997, allowing for one connection point between the telecommunications closet and the outlet. This allowed for zone cabling in the open office, as opposed to the original standard that required only uninterrupted 'home run' cables to the outlet. TSB 75 has since been integrated into the newest revision of the standard, known as T568-B.

Telecommunications Cabling - Generic industry term for building cabling that carries voice and data signals. This is now usually the exact same cabling for both services, allowing for ease of reconfiguration.

Telecommunications Closet (TC) - An enclosed space for housing telecommunications equipment, cable terminations, and cross-connects. The closet is also the recognized cross-connect between the backbone cable and horizontal cabling. Also known as the 'wiring closet.' The requirement is a minimum of one per floor in any given building.