European Unified Cable Colours

Buy the relevant BS EN XXXX standards.

They will tell you all you need to know.

You're a bit out of date, the harmonised colours have been in place for a decade.

If and when we get to vote on the UK's continuing membership of the EU.

I'd like to see the clock turned back to Red White Blue Black, solid Green for earth. The colours changed to Red Yellow Blue Black during my apprenticeship.

Which idiot came up with the idea of making black a phase colour when it was neutral before, blue formally a phase colour changed to neutral needs taking out and shooting!

I'll be dead before anything is done about it.

It helps to print colors verbally in white on black wires. This method has better immunity to fading, to say nothing of color-blind electricians. Distinguishing between tan and pink on 30-year-old wires is a drag.

Is the OP referring to the color-coding of conductors within a cable (e.g. BN/BK/GY/BU/GNYE vs. former BN/BK/BK/BU/GNYE) or to the way colors are assigned in use (e.g. GNYE for PE, BU for N or DC control circuits, etc.)?

Relying only on color coding can have letal consquences because in addition to the currently valid color schemes many old ones have been used in the past. For example RDYE (i.e. bicolor Red/Yellow) can be found as protective earth in some countries and as phase in others.

And here I'm not even referring to what can be found in less developed parts of the world.

A whole book could be written about how to assign conductor colors but it's sort of a pointless discussion as beside a very few colors which cannot be freely assigned, in most cases the remaining colors are assigned according to the wishes of the client and that's it.

Mostly GNYE has to be used for PE and some blue (forget the dark and ligh blue distinction) for N. Even OG which should be used for something like external interlock circuits is not uniformally assigned.

The corresponding EN is anyway lame because the proposed color assignation system is not very logical (as was the so stupid idea to formerly include two black wires in the flexible 5 conductors CENELEC cable).

Another good example of eurocratism where standards are sometimes issued by people lacking pratical experience.

I don't know how things work across the pond, but I was taught that electricity is color-blind.