The TIA standard defines the parameters for each part of the cabling system, which includes work area wiring, horizontal wiring, telecommunication closets, equipment rooms and cross- connects, backbone (vertical) wiring, and entrance facilities. Each of these is described next. When standards are incorporated into all areas of the design, consistency in equipment, build out, performance and testing creates a unified communications system. Below are the areas to be considered
The work area wiring subsystem consists of the communication outlets (wall boxes and faceplates), wiring, and connectors needed to connect the work area equipment (computers, printers, and so on) via the horizontal wiring subsystem to the telecommunication closet. The standard requires that two outlets be provided at each wall plate-one for voice and one for data.
The horizontal wiring system runs from each workstation outlet to the telecommunication closet. The maximum horizontal distance from the telecommunication closet to the communication outlets is 90 meters (295 feet) independent of media type. An additional 6 meters (20 feet) is allowed for patch cables at the telecommunication closet and at the workstation, but the combined length cannot exceed 10 meters (33 feet). As mentioned earlier, the work area must provide two outlets. The horizontal cable should be four-pair 100-ohm UTP cable (the latest standards specify Category 5E), two-fiber 62.5/125-mm fiber-optic cable, or multimode 50/125-mm multimode fiber-optic cable. Coaxial cable is no longer recommended.
The telecommunication closet contains the connection equipment for workstations in the immediate area and a cross-connection to an equipment room. The telecommunication closet is a general facility that can provide horizontal wiring connections, as well as entrance facility connections. There is no limit on the number of telecommunication closets allowed. Some floors in multistory office buildings may have multiple telecommunication closets, depending on the floor plan. These may be connected to an equipment room on the same floor.
An equipment room provides a termination point for backbone cabling that is connected to one or more telecommunication closets. It may also be the main cross-connection point for the entire facility. In a campus environment, each building may have its own equipment room, to which telecommunication closet equipment is connected, and the equipment in this room may then be connected to a central campus facility that provides the main cross-connect for the entire campus.
The backbone wiring runs up through the floors of the building (risers) or across a campus and provides the interconnection for equipment rooms and telecommunication closets. The distance limitations of this cabling depend on the type of cable and facilities it connects. Refer to Figure T-11 and the following table. Note that UTP is limited to 90 meters.
The entrance facility contains the telecommunication service entrance to the building. This facility may also contain campus-wide backbone connections. It also contains the network demarcation point, which is the interconnection to the local exchange Carrier’s telecommunication facilities. The demarcation point is typically 12 inches from where the carrier’s facilities enter the building, but the carrier may designate otherwise.