|  | 5.2 | Cable Specifications and Termination
| 5.2.3 | Explain the details of TIA/EIA-568-A

The TIA/EIA standards address six elements of the LAN cabling process. These are:

- horizontal cabling
- telecommunications closets
- backbone cabling
- equipment rooms
- work areas
- entrance facilities

This lesson will focus on TIA/EIA-568-A standards for horizontal cabling, which defines horizontal cabling as cabling that runs from a telecommunications outlet to a horizontal cross-connect. It includes the networking medium that runs along a horizontal pathway, the telecommunications outlet or connector, the mechanical terminations in the wiring closet, and the patch cords or jumpers in the wiring closet. In short, horizontal cabling includes the networking media that is used in the area that extends from the wiring closet to a workstation.

TIA/EIA-568-A contains specifications governing cable performance. It calls for running two cables, one for voice and one for data, to each outlet. Of the two cables, the one for voice must be four-pair UTP. The TIA/EIA-568-A standard specifies five categories in the specifications. These are category 1 (CAT 1), category 2 (CAT 2), category 3 (CAT 3), category 4 (CAT 4), and category 5 (CAT 5) cabling. Of these, only CAT 3, CAT 4, and CAT 5 are recognized for use in LANs. Of these three categories, CAT 5 is the one most frequently recommended and implemented in installations today.

The networking media that are recognized for these categories are the ones you have studied:

- shielded twisted-pair
- unshielded twisted-pair
- fiber-optic cable
- coaxial cable

For shielded twisted-pair cable, the TIA/EIA-568-A standard calls for two pair 150 ohm cable. For unshielded-twisted pair, the standard calls for four pair 100 ohm cable. For fiber-optic, the standard calls for two fibers of 62.5/125 multi-mode cable. Although 50 ohm coaxial cable is a recognized type of networking media in TIA/EIA-568-A, it is not recommended for new installations. Moreover, this type of coaxial cable is expected to be removed from the list of recognized networking media the next time this standard is revised.

For the horizontal cabling component, TIA/EIA-568A requires a minimum of two telecommunications outlets or connectors at each work area. This telecommunications outlet/connector is supported by two cables. The first is a four-pair 100 ohm CAT 3 or higher UTP cable along with its appropriate connector. The second can be any one of the following:

- four-pair 100 ohm unshielded twisted-pair cable and its appropriate connector
- 150 ohm shielded twisted-pair cable and its appropriate connector
- coaxial cable and its appropriate connector
- two-fiber 62.5/125 µ optical fiber cable and its appropriate connector

According to TIA/EIA-568-A, the maximum distance for cable runs in horizontal cabling is 90 meters (m). This is true for all types of CAT 5 UTP recognized networking media. The standard also specifies that patch cords or cross-connect jumpers located at the horizontal cross-connect cannot exceed 6 m in length. TIA/EIA-568-A also allows 3 m for patch cords that are used to connect equipment at the work area. The total length of the patch cords and cross-connect jumpers used in the horizontal cabling cannot exceed 10 m. A final specification for horizontal cabling contained in TIA/EIA-568-A requires that all grounding and bonding must conform to TIA/EIA-607 as well as to any other applicable codes.

The latest industry standards being developed are for Cat 5e, Cat 6, and Cat 7 cabling, all of which offer improvements over Cat 5.

Upcoming Changes in Cabling Standards

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| Industry Standards for Structured Cabling