T568 A or T568 B Wiring Schemes- What’s the Difference?

Based on TIA/EIA-568-B.1-2001, the T568A and T568B wiring schemes define the pin-out, or order of connections, for wires in eight-pin modular connector plugs and jacks.

The only difference between T568A and T568B is that pairs 2 and 3 (orange and green) are swapped. Both configurations wire the pins “straight through”, i.e., pins 1 through 8 on one end are connected to pins 1 through 8 on the other end, and the same sets of pins are paired in both configurations: pins 1 and 2 form a pair, as do 3 and 6, 4 and 5 and 7 and 8.

Cables that are terminated with differing standards on each end will not function normally, however mixing T568A-terminated patch cords with T568B-terminated horizontal cables (or the reverse) will not produce pinout problems in a facility, although it may slightly degrade signal quality, This effect is marginal and certainly no greater than that produced by mixing cable brands in-channel.

 

T568A and T568B Wiring Assignments:

T568A and T568B Wiring Assignments

Wiring Standards
Pin # T568B T568A
1 White/Orange White/Green
2 Orange Green
3 White/Green White/Orange
4 Blue Blue
5 White/Blue White/Blue
6 Green Orange
7 White/Brown White/Brown
8 Brown Brown

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