Structured Cabling System
Work area
The work area consists of all the components between the telecommunications outlet and the user’s desktop workstation equipment. This covers:
• Telecommunications outlets, including wallplates, faceplates, surface-mount boxes, etc.
• Patch cables.
• Adapters, including connectors, and modular jacks.
• Workstation equipment, such as PCs, telephones, printers, etc. although they aren’t included in the standard.
The work area should be well managed even though it is designed for frequent changes. There are a few specific recommendations in TIA/EIA-568-B.1:
• You should install a minimum of two telecommunications outlets in each work area.
– The first outlet shall be a 100-ohm,
8-position modular jack, CAT3 or higher.
It’s very advisable to use CAT5e or higher.
– The second outlet can be another 100-ohm,
8-position modular jack (minimum CAT5e or CAT6), or...
– A 2-fiber, 62.5- or 50-micron fiber SC, ST, or other small-form factor duplex fiber connector.
• UTP wiring should follow T568A or T568B schemes. (See right.)
• The 4-pair UTP patch cable from the telecommunications outlet to the workstation equipment should be no more than 5 meters
(16.4 ft.).
• Make sure the equipment cords, patch cables, and modular jacks all have the same performance rating.
• Follow standard installation practices and maintain proper pair twists, bend radius, etc.
• Use different pathways for electrical wiring and structured cabling.
• Estimate pathway capacity at 20–40% fill.
• Run an independent pathway to control centers, reception areas, and other high-activity spaces.
• An electrical outlet should be installed within
3 feet (9.1 m) and at the same height.
T568A and T568B pinning.
There are two approved pinning methods: T568A and T568B. The T568A scheme is the one recognized and used by the U.S. government. The T568A pinning is also common in Canada and in other parts of the world.
The T568B pinning is the one used by AT&T ® and is the de facto standard in the U.S.
By the way, the T stands for termination, and not
TIA as commonly thought.
Whichever scheme you choose, stick to it. All pin/pair assignments must conform to one standard or the other. Mixing the two can cause crossed pairs, which just doesn’t work. In addition, you must follow established telecommunications cabling color schemes.
Pair 1
Pair 2
Pair 3
Pair 4
T568B
T568A
Wire Color
White/Blue
Blue/White
White/Orange
Orange/White
White/Green
Green/White
White/Brown
Brown/White
3
4
2
3
4
Pair
1
1
2
Wiring Color Codes
Tip/Ring
Tip 1
Ring 1
Tip 2
Ring 2
Tip 3
Ring 3
Tip 4
Ring 4
T568A Jack Pin #
5
4
3
2
7
6
1
8
T568B Jack Pin #
5
4
1
6
7
2
3
8
21
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