sundance-communications.com/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring 568A/568B standard question

satpir, the issue was documenting the proper wiring sequence of hand-made patch cords. Obviously everyone thinks the same, just not at the same time .

Before 1995 568B was the standard (better performance at higher speeds plus being the existing WECO standard.) 568A came before the committee due to the "standardization" of the voice/data industrial manufacturers. That way any CG could plug in his computer or TDM 2-pair telephone without needing to know the difference. This was also the year that the same manufacturers wanted metric as the standard for equipment racks. How do I know? I worked with one of the committee members when this was happening.

The only docs you'll find are the Bicsi docs and they don't explain "why". We had a guy that worked for Fluke on the BB for a while. He said it didn't make any difference. But he could not defend that statement with facts or theory. He no longer participates.

Enjoy the board, watch your "caps", and please stay with the current posts.

Allway's use jack's and factory made patchcord's.

How can you go wrong?

There seems to be an awful lot of confusion out there over the different twists in the cable, and little real understanding that the purpose is merely to reduce crosstalk.

A couple of you will recall a recent discussion about this elsewhere in which it was stated that the white/orange pair in CAT5 always has the tightest twist. Not so, as this sample demonstrates:



Twists per foot:

White/blue = 32
White/orange = 19.5
White/green = 25.5
White/brown = 18

It doesn't matter which color pair has which number of twists per foot; it matters that 2 pairs don't have the SAME number of twists per foot, and that the twists per foot of the 4 pairs are different from each other, and fit into some scheme that prevents harmonics and inductance between pairs. Finally, it all comes down to keeping signals on balanced pairs, not split bewteen two sides of different pairs.

I think we have covered all these requirements through out this thread.

T568A vs T568B:

As posted back in June 2005 on this forum, it can make a difference which code you choose. It the orange pair on your cable is the worst performing pair and you connect it to a connecting where it's worst performing pair is 3,6 then wiring it to T568A is going to produce a worse RL margin than wiring it to T568B. If the RL margin on the cable is equal between the orange and green pair, you will see little or know difference.