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Twisted pair colours

Rob the Spark

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Often not in drawings IME. I think that the reasoning is that anyone competent knows how to terminate electrical power cables...


But electrical power cables ALL comply to a standard (or two ) so there's no need to document it. Everything else ought to reference either a drawing/document or an 'industry' standard ie "uses the BBC/GPO/BT colour code".

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I still think in BOGNS where N is Brown because B is Blue. In my time the most common internal "large" cable was 41 wire used for Key and Lamps and the 2+10 systems. As long as one has a system and everyone gets used to it the scale doesn't matter and urban (underground) jointers used to work on 2,000 pair cables every day.

The 41st wire was Black or (K) and there were variations in internal cables once one got above 41W with Red, Black, Turquoise as mating colours to follow White. Most BR members will see Blue/Bluewhite, Blue/Orangewhite pairs at home but the basic BOGNS is till the core.


For bigger twisted pair cables one tip is to allow a little more spare cable than you really need to terminate. Then when the sheath is removed, if you are good or lucky, the pairs fall out just like one of those fibre optic lamps. A gentle shake can save hours and much grief.

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