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What a strange colouring.

All part of the new scheme of things. Previously regular cables were:

2-core: red, black
3-core: red, yellow, blue
4-core: red, yellow, blue, black.

(Substitute white for yellow before 1965.)

With the the new color code the cores have just been replaced one-for-one, so:

2-core: brown, blue
3-core: brown, black, gray
4-core: brown, black, gray, blue.


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That'll cause some confusion to someone.

There has already been one report on the IEE website of someone getting confused between the old and new colors and cross-connecting a phase and neutral on a 3-ph system. [Linked Image]

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However, there was a rare cable here that I haven't seen in ages, it was the old 2x Red and 1 Black,

I don't recall ever seeing anything like that here.