568A vs. 568B. Which should you use?

568A vs. 568B. Which should you use?

There are two accepted standards for 8-wire data network jacks (commonly and incorrectly called "RJ-45.")

ANSI/TIA/EIA-568-B "Commercial Building Telecommunications Cabling Standard" lists both wiring configurations. T568B is the most prevalent for commercial installations, and was used by AT&T for the original Merlin phone systems. To help you remember, associate "B" with "Bell."

ANSI/TIA/EIA-570-B "Residential Telecommunications Cabling Standards" recommends T568A

  • If the installation is residential, choose T568A unless other conditions apply (see below). The two inner pairs of 568A are wired the same as a two-line phone jack.
  • 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 for either T568A or T568B, use that wiring scheme.
  • Make sure both ends of a cable are wired the same way.

Jack Wiring  
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

(Based on info from Leviton)