modular jack

[amazing electric]

which one do i punch down A or B?

 

[TOOL_5150]

which one do i punch down A or B?

Well that depends on the installation. What is the 'other side' wired as? Do you want a straight through or cross over connection? B is common in america, But i never just assumed any system was just B. Sounds like you need to do a little investigation, and you will find your answer. :smile:

~Matt

 

[barbeer]

Yeah - investigate! B as stated is more prevalent.

 

[LarryFine]

which one do i punch down A or B?

Electrically speaking, it doesn't matter. The difference is whether the green or orange pairs are used, along with the blue pair. (Only two of the four pairs are used for ethernet.)

The T568A config uses the same colors as phone wiring:the blue pair (L1) in the middle, flanked by the orange pair (L2), while T568B has the blue pair flanked by the green pair.

As long as both ends of any cable or run are terminated the same, the function will not be affected. The only physical difference between pairs is twist rate to minimize cross-talk.

Traditionally, T568B (think 'B for business') is used in commercial installations, while T568A is more likely to be found in phone wiring and residential ethernet done by phone techs.