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#159631 01/09/05 11:45 PM
Joined: Jun 2001
Posts: 141
amp-man Offline OP
O.K., so you know that the 25-pair color code base colors are blue, orange, green, brown, and slate (that's Bellspeak for gray). Abbreviated bl, or, gr, bn, sl.

One way to remember the colors and sequence is the nmenonic


The band colors are white, red, black, yellow, violet (purple). I don't know any memory trick for these. Does anyone out there know one?



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#159632 01/10/05 01:31 AM
Joined: May 2003
Posts: 2,876
e57 Offline
There is one, but.... (Not appropriate)

Maybe we should make up a new one.

Mark Heller
"Well - I oughta....." -Jackie Gleason
#159633 01/10/05 08:48 AM
Joined: Aug 2001
Posts: 7,520
It's funny, but I learned a lot of these codes off by heart when I was younger and only discovered some of the memory aids in later years, by which time I didn't need them, of course!

There is one, but.... (Not appropriate)
I once heard one for the resistor color code which fits that category too. Certainly not for polite society and would probably upset the Thought Police these days as well.

#159634 01/10/05 05:43 PM
Joined: Dec 2003
Posts: 886

Ok, but what's the other half, the one for white, red, black, yellow, violet.

I know I heard these years ago but I can't remember.


#159635 01/10/05 06:44 PM
Joined: Apr 2002
Posts: 2,527
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: (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;

white/blue wt/bl
white/orange wt/or
white/green wt/gr
white/brown wt/bn
white/slate wt/sl

The next five are the "red" pairs:

red/blue rd/bl
red/orange rd/or
red/green rd/gr
red/brown rd/bn
red/slate rd/sl

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 <> - 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:



Newsgroups: comp.dcom.cabling
From: (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

While (white tips)
Running (red tips)
Backwards (black tips)
You'll (yellow tips)
Vomit (violet tips)

#159636 01/11/05 06:09 AM
Joined: Aug 2001
Posts: 7,520
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! [Linked Image]

#159637 01/11/05 09:47 AM
Joined: Dec 2002
Posts: 1,253
djk Offline
Paul: I recently had that very problem. Not much fun when you've about 2inches of cable at the back fo a box to work with.

Ended up using the trial and error until I found a dial tone approach!

#159638 01/11/05 07:30 PM
Joined: Nov 2002
Posts: 456
Not to mention the cheap 3 pair wire, which doesn't cross refer the white with the color of the pair (so there is 3 whit wires, plus the 3 colored wires).

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