T568A and T568B

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 pinout, 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.

T568 A or T568 B- Which One Should I Use?

• If the installation is residential, choose T568A unless other conditions apply (see below).
• If there is pre-existing voice/data wiring (remodel, moves, adds, changes), duplicate this wiring scheme on any new connection.
• If project specifications are available, use the specified wiring configuration.
• If components used within the project are internally wired either T568A or T568B, duplicate this wiring scheme.

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