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pauluk: the yel-gn-pur colors were used on the primary side in substations, too (20kV). maybe they did it that way to avoid mixed color codes in their switchgear.
at least it was a code to clearly identify each phase.
Before the new gray phase conductor, some used the sequence of wires in a cable to identify each phase in black-black-brown, but not everybody. In the company where i did my apprenticeship, we used the black one between gn/yel and blue as L1, the brown one as L2 and the remaining black one as L3.
Thus leading to another confusion, as now brown is L1, not L2 anymore.....

Sadly I think not everyone here today goes strictly for the brown-black-gray sequence, I believe it's just a "recommendation" here. At least they check for correct phase rotation more often nowadays.

djk: Those rules sound quite like the German ones, but I believe we have one exception for the blue wire. In a 3-wire cable brown-blue-gn/yel to a single switch, I believe the blue one may be used as switch return. It was that way a few years ago, I'll check if it's still OK.

It is a little surprising to see that a modern country such as Germary not standardrizing the coloring. In the U.S. there is a few requirements but for the most part, the coloring system is standardized but not required. For the most part no matter where you go in the US, you open a panel and you will see the standards followed. Makes a job a whole lot easier.

Well, nowadays colors are standardized as far as cable is concerned.

There are a few exceptions though. Where a neutral is present it has to be blue and the only blue wire. Where no neutral is needed and present the blue wire can be used as a phase conductor (frequently done for switch loops).

Austria does allow the grey conductor of 4 core cable to be re-identified blue and used as a neutral.

Where conduit is used (very common in Austria) the core colors are merely recommendations - only yellow/green and blue are limited to ground and neutral, phase conductors can be any color but green, yellow and yellow/green. Typically electricians pull three black wires for the phases.

Don't ask me why, but Germany loves cable... they seem to think conduit is old-fashioned. Austria is just the other way round - our sparkies think burying cable in masonry or concrete is barbaric. With this opinion Germany seems to be pretty much alone in Continental Europe, almost all other countries I have visited so far prefer conduit.

The yellow-green-purple color scheme was only used for distribution, both medium and low voltage, sometimes up to the panel of a house or apartment. In this scheme they even took the phase colors serious, I've seen a 1955 apartment building where each apartment was fed with either yellow, grey and red, green, grey and red or purple, grey and red. From the panel onwards they continued with black phase and neutral, no ground...

A similar limitation is found in BS7671 -- Green/yellow cores may not be re-identified for any other purpose than earthing.





However, BS7671 contains neither of these limitations.

Basically, you may not re-identify a green/yellow wire to use it for something other than an earth, but you may freely re-identify any other color if you wish.

So a blue on switch loop is sleeved brown to use as a return. If you are using 3-core (e.g. SWA) which has the brown/black/gray phase colors, you can leave the brown as is to use as the phase, then sleeve the other two conductors in blue and green/yellow for neutral and earth.

This basic principle hasn't changed from the old color code, e.g. red sleeving on black to use as a phase, black sleeving on a blue to use as a neutral, etc.



That's an interesting one, since strictly speaking the I.E.E. Regs (since long before they became BS7671) have said that a single-phase circuit derived from 3-phase should always use the "basic" live color -- Formerly red, now brown. Use of the other phase colors (yellow & blue, now black & gray) is permitted on a single-phase branch feeder up to the final distribution panel though.