The table below gives the colour-coding for internal communications cables up to 100 pairs. The colour-code is based on the five-colour sequence of Blue, Orange, Green, Brown, Slate which are used in that order for the first five pairs. Knowing this sequence of five colours allows you to easily determine the order of the remaining pairs as follows:
The sixth pair uses the first colour (blue) with a white stripe (blue/white). Subsequent pairs (up to pair 10) use blue with each of the remaining colours in-turn (blue/orange, blue/green, blue/brown and blue/slate.
We have already used the blue/white combination so now (for pair 11) we use Orange (the second colour in our sequence) with a white stripe (orange/white). We then again use Orange with each of the remaining colours (orange/green, orange/brown, orange/slate (for pair 14).
Now we use Green with a white stripe (green/white) for pair 15, followed by green with each of the remaining colours down to green/slate for pair 17. Brown/white and brown/slate follows the same sequence (pairs 18 & 19) and we finish with slate/white for pair 20.
We now start all over again but this time with a different coloured "mate" than white.
Pairs 21 to 40 repeat the "Line -" colours but with a YELLOW mate for "Line +".
Pairs 41 to 60 repeat the "Line -" colours but with a BLACK mate for "Line +".
Pairs 61 to 80 repeat the "Line -" colours but with a VIOLET mate for "Line +".
Pairs 81 to 100 repeat the "Line -" colours but with a RED mate for "Line +".
|Pair||Line (+)||Line (-)|