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

Hi guys, I just got a bunch of new 8p8c jacks for ethernet connections, that have the wiring digrams on them, but I'm not sure if I should wire it A or B. I've read a lot online about how to wire it A or B, but not sure why I should use one over the other. I'd just like to do whatever's more common so whoever has to go behind me won't have any trouble.
Thanks guys!

I'm not really sure that it matters just as long as you wire both the jack end and the plug end the same. Some will tell you that 568A is for residential and 568B is for commercial. The good thing about 568A is that you can generally use it for telephone as well.

There are DeFacto standards and DeJure standards. The first is by weight of the big boys using it and everyone else copying. The second is set by a governing body. TIA/EIA 586A and 586B are dejure standards. 586B is a clone of the older (don't ask me the number) Bell System standard, which was the defacto standard.

Just installed a new office, ran quad-four to each desk -- four four-pair cat-5e, jack panel in the terminal room to quad jacks under the desks. Red jack has the corporate 100baseT network, to the IP phone, daisy-chained to the computer. Blue will be going to a 10baseT DSL backup in case both D3s fail (yeah, right!) Green will be carrying a 9600 baud RS-232 connection. White is an analog line for modem/fax. Back the terminal room I have a cable with 8-pin modular plugs carrying the T1 from the demarq to the routers.

You might say that the 8-pin modular is the Jack of All Trades.

568A is the preferred method of the two. That said, as long as you do both ends the same and you are consistent in the overall installation, either method is acceptable.

I would only use B if there are already some terminations done in that style at this site.

Well, I have to have it the same way as the patch cables, right? How do I know how those are wired?

568A is the preferred method of the two? I am not so sure about that, at least not in the U.S. The popular 568B jack wiring standard in the U.S. was a simple association to the jack that looked like ATT/Western Electric's part number for 258 or 259 adapters.

Somewhere along the way, USOC and manufacturer's standards crossed paths. While, they were similar, yet not the same. I don't know if the U.S. USOC standards made their way to Canada, but the two separate standards between A and B still exist.

Since these adapters were so popular and commonplace, the term "258A" was frequently referred to as a wiring pattern 568B (take a look at an old supplier's catalog). While long-gone from production, these adapters hold their place in history as perhaps the most misunderstood part number. They ended up becoming a worldwide standard now known as 568B.

We are a worldwide support forum, so preferences vary between countries and continents. I suppose like many other posts on this subject, all that really matters is the fact that both ends of the cable are terminated using the same wiring standard.

Ed, thanks as always, you are a veritable encyclopedia of telcom information

What about the patch cables though? Do I need to make sure the jacks (at _both_ ends) are wired same as patch cables?

Here in Chicago I rarely see anything wired 568A

Chad, while I was busy correcting the typos in my original post I found that you had replied. I was too busy telling you how to build the watch instead of simply telling the time.

Here's the short answer that I should have given earlier: As long as the cable run between the outlet and patch panel are wired using the same standard (A or B), then you can use either 568A or 568B patch cords. The only restriction is that the patch cords must be the same type at both ends to function.

as long as its wired the same both ends a or b works fine for two pair telephone .

I thought the standard for structred cabling called for A . we dont do structred so I havent paid tht close attenion