Here’s a few usenet hits from google on [WECO] color coding. Skip to articles 2 and 3 if a history lesson is of no interest.
Newsgroups: comp.dcom.telecom From: jdea...@pacsbb.bpa.bell-atl.com (John Dearing) Date: 4 Aug 89 06:00:00 GMT Subject: A Bell of PA Technician Explains Color Coding
[Moderator's Note: I am sorry to advise that the original subject title and header info was lost in transit between chinet and here. I reconstructed the header, however the body of his letter made it here intact, and follows below. PT]
I hope that this reply gets thru to you (email is sometimes flaky). In a recent Telecom Digest article you asked what the color code was for telephone wiring. As a Services Technician with over 14 years of service with Bell of Pennsylvania, I thought I'd reply. The system employed throughout the (used-to-be) Bell System was actually very simple. There were five colors assigned to "tip" and five colors assigned to "ring". This gives a total combination of twenty-five pairs (very convenient!).
The colors assigned to the "tip" are;
white wt red rd black bk yellow yl violet vi
The colors assigned to the "ring" are;
blue bl orange or green gr brown br slate sl (sometimes mistakenly called gray)
Standard phone convention is to identify the "tip" first and then the "ring" when referring to a pair. Thus, the first five pairs of a telephone cable are the "white" pairs;
And so on, until all twenty five pairs are identified. What happens when there are more than twenty-five pairs in a cable? Simple, enclose each twenty-five pair group in a color coded binder. And guess what the color coding is for the binder. Yep, the same as the wires in the binder. The first binder group is the "white/blue" binder the second is the "white/orange" binder, and so on. If it is necessary to refer to the twenty-sixth pair of a fifty pair cable it is referred to as "two white/blue" or 2-wt/bl. The seventy-ninth pair in a one-hundred pair cable is called "four white/brown" or 4-wt/bn. This all holds true for the first twenty-four binders in a cable. The twenty-fifth binder is a little different, and my recollection is a little hazy but I believe the binder colors are white-white-blue. Yes that's two whites and a blue. It might be two blues and a white. It's been a long time since I was in a cable over six hundred pairs. One thing I know for sure is that they double up on one of the binder colors after the twenty-fourth binder group.
There is also a convention for the positioning the pairs on connecting blocks. The Ring is usually on the Right and the Tip is usually on the Top. As you can see there is a pattern here, Ring-Red-Right and Tip-Top. I guess this was done to make it easier for us dumb installers to remember! |-)
The only difference in the color coding between telephone cable (the stuff used outside and strung along poles or underground in conduit) and telephone inside wiring (the gray colored stuff in the walls and up in the ceiling) is that the inside wire has each pair traced with the color of its mate. That is, the first pair is a white wire with a blue tracer and its mate is blue with a white tracer. This is done to avoid "splitting" a pair. Splitting is getting the ring of one pair and the tip of another. In outside phone cable each pair is twisted with its mate and the chances of splitting a pair are not as great (although it's been known to happen ;-)).
With wiring done inside a house, a little history is in order. Back when we had party-lines,(I know, we still do, but very few still in service and none available for new service) three wires were necessary because a ground was required to make the bell ring. So, the original phone wiring had three conductors, red, green and yellow. Red and green were ring and tip respectively and yellow was the ground. Then people started getting away from party lines and into princess and trimline phones with lights in the dial. The yellow was no longer the ground and a black wire was added and the yellow and black were used to supply power for the lamps from a small transformer. Time marches on, and now people are getting second lines installed in their homes. Since the new phones get the power for their lamps from the phone line directly, the yellow and black are now "spare". The yellow is usually the ring and black is the tip. Of course, houses that have been pre-wired with six-pair inside wire would normally have line 1 on the white/blue pair and line 2 on the white/orange pair. In many pre-wire installations I have found that the sixth pair (red/blue) was used for transformer power, although I don't believe that was ever an official practice.
I hope that this info is of some help. Feel free to put this into the Digest, if you want.
John Dearing (jdearin @ pacsbb)
Newsgroups: comp.dcom.cabling From: Gil Stamper <gstam...@us.hsanet.net> - Find messages by this author Date: 1999/04/25 Subject: Re: 25pr color mnemonics
The guys I work with who wire 25 pair cables for lunch, taught me this:
Bell Operators Give Better Service
Why Run Backwards You'll Vomit
Newsgroups: comp.dcom.cabling From: prot...@aol.com (ProTInc) - Find messages by this author Date: 1999/05/19 Subject: Re: 25pr color mnemonics
Blue sky Orange sun Green grass Brown dirt Slate is in the ground
The only difference in the color coding between telephone cable (the stuff used outside and strung along poles or underground in conduit) and telephone inside wiring (the gray colored stuff in the walls and up in the ceiling) is that the inside wire has each pair traced with the color of its mate.
It's worth emphasizing that point for anyone who hasn't worked on telephone plant. Many cables have just solid-color insulation, no bands or tracers, so you rely on the twisted pairs to identify each circuit, e.g. #3 will be a plain white (tip) and a plain green (ring) wire.
The problem comes when somebody new decides to untwist all the pairs to "help" and you're left with five wires of each color, none matched up with its mate!