atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services Cabling Telephones Systems Wiring Reasons for 568B

There is a discussion going on here:
https://community.spiceworks.com/topic/222086-568a-or-568b?page=6#entry-1367213
about when to use 568A or 568B wiring configurations.

I vaguley remember a story that A was introduced first by ATT, Bell, IBM? One of the big players. They seemed to have some control of the wiring spec. So, when somone else wanted to use the same configuration, but 'big company' wouldn't let them, they just swapped pair two and three and called it B. and the rest is history, as they say.

I wish I could remember the source of this story, or maybe I'm dreaming it. Does anyone else remember anything like this?

Thanks.
Jim

My understanding is the the "B" configuration was actually Western Electric's configuration that Bell had been using before the "standards" were created - after the committee decided "let's do it this way" (568), they had to backtrack and call their wiring 568A, and incorporate everything already done by WE as 568B

The wiring scheme was developed by Western Electric back in the early 1970's to support the MET (Modular Electronic Telephone) sets on the Dimension PBX. It had no 'RJ' designation, as it wasn't a network jack.

IBM was never in the picture.

568A wiring was more of a continuation of the RJ11, 14 and 25 mindset, where pairs radiate out from the center two pins.

There was the problem: 568A made more sense since it kept in line with an existing standard. On the other hand, by this time, Western Electric systems had now migrated to the Horizon PBX and the Merlin key systems. With that said, there were likely millions and millions of "568B" jacks out there, so there was no way that they were going to fade into the sunset. In the US, it was decided to just allow both standards to coexist.

The WECO wiring standard soon adapted to the misnomer of "258A" wiring. This originated somewhere by a person referring to a 258A adapter, which was largely popular in areas where AT&T or Bell companies had a presence. The 258A was just an adapter that converted a 25 pair cable into six 8P8C jacks wired with the WECO (568B) pattern.

This is also why you don't see 568B wiring as much in Canada. Western Electric/AT&T didn't have as much of a presence there, so it never really took off.

EDIT: Jim beat me to it

This made me laugh:
"the standard for cabling is 568B and use CAT6, if you're not using at least CAT6 with 568b, your essentially limiting your network to a 5 year old standard."

As always, Ed is a font of information on "RJ 45" and wiring.... :rofl:

In 1995 I was working with a guy who set on the BICSI standards committee....the "fur-in-ers" all wanted BICSI to set "A" as the standard as their then two pair telephone sets would work without rewiring. That was when they wanted to do away with all standard rack deminsions and do metric. Neither happened back then.

:thumb: :thumb: :thumb:

Ed gets my vote as well.

It's amazing how those millennium generation geeks don't know history. They all think nothing existed before their sacred computers and ethernet so obviously 568A and B has to come from some IT standard.

It's also amazing how there is so much mis-information on the internet. Ed provided a through explanation. Maybe he should make it an informational sticky so Google will pick it up and those half wits can find it and learn something.

-Hal

They'd only believe it if he signed it as an IT expert....something not likely to happen :rofl:

How about Ed the IT Consultant?

-Hal

"You can't believe everything you read on the internet." Abraham Lincoln