Regarding colour coding: After some searching I located the source of the information. The text below is a slightly edited and shorted version of the following NG posting. Although it claims to apply to mains cords only, it seem to be valid for fixed wiring too.
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Andrew Emmerson (midshires@cix.compulink.co.uk)
Safety or heresy
rec.antiques.radio+phono
1995/10/17
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Mains Cords
By this we mean flexible appliance wiring or line cords, not the fixed cable or wiring inside the walls. All colour code combinations are given in the order L, N, E: In other words line (live), neutral and earth (ground).
The current general standard is Brown, Blue, Yellow/Green striped and this is mandatory in most European countries and on items intended for sale in those countries. The colours were chosen not for their association (otherwise brown would be earth!) for reasons set up below.
Elsewhere in the world and also in Europe in previous times, these colour codings vary widely. The following combinations can be encountered. Again the order is L, N, E and the list is not intended to be exhaustive.
Belgium: Red, yellow or blue, Grey, Black.
Germany: Usually Grey, Black, Red.
Great Britain: Red, Black, Green.
Netherlands: Any colour but grey or red, Red, Grey.
Russia: Red, Grey, Black.
Switzerland: Red, Grey, Yellow or yellow/red.
USA, Canada: Black, White, Green.
The foregoing should make it clear why a unified colour coding of wires was necessary. Green is by no means the obvious colour for earth either:
before standard colours were adopted, earth was red in Austria, Finland, Germany, Norway, and Sweden; black in Belgium and Russia, grey in the Netherlands and Poland, yellow in Switzerland and green in Britain and North America. Three cheers for standardisation!
The choice of colours for the world-wide system was not arbitrary either; earth (ground) had to be distinguished and making it striped was an inspired choice. The other two colours had to be clearly distinguishable, even by people who suffer colour-blindness, and blue and brown were judged the most clearly different shades by experts in this field.
[This message has been edited by C-H (edited 09-28-2002).]
