T568A & T568B

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Standard 4-Pair Wiring Color Codes
Pair 1	T	White/Blue
	R	Blue/White
Pair 2	T	White/Orange
	R	Orange/White
Pair 3	T	White/Green
	R	Green/White
Pair 4	T	White/Brown
	R	Brown/White

Note: For 6-wire jacks use pair 1, 2 and 3 color codes. For 4-wire jacks, use Pair 1 and 2 color codes.

Q. T568A and T568B wiring: what's the difference, and how do I know which one to use?

A. T568A and T568B are the two wiring standards for an 8-position modular connector, permitted under the TIA/EIA-568-A  wiring standards document. The only difference between T568A and T568B (also known as Weco, AT&T 258A) is that the orange and green wire pairs (pairs two and three) are interchanged

How to decide which wiring pattern to use:

1. Does the job specification call out a wiring pattern?
2. Does the customer/end user have a preference for T568A or T568B?
3. Have patch panels already been purchased for the job? If so, they will probably be either T568A or T568B. The jacks should be wired to the same pattern as the panels.
4. Are you adding on to an existing wiring plant? If so, your new wiring should match the existing wiring.

If none of the factors above apply, either T568A or T568B may be used. It is important to ensure that the workstation connectors and the patch panels are wired to the same pattern. T568B is commonly used in commercial installations, while T568A is prevalent in residential installations.