Gentlemen,
for clarification a few additions to the color (or coulour, for Andy)
system in electricity supply, used in Germany (DIN and VDE) and most of
Europe:
- First, always keep neutral and ground apart! The FI switch is designed
to trip at any connection between them, even in absence of mains voltage
in that particular circuit. Generally, four leads come into the house
from the community supply:
Brown, black, black are the three phases P1, P2, P3 or L1, L2, L3
(formerly called X, Y, Z)
Neutral, blue (comes also from the transformer station)
- Earth (is connected to ground only at the very location, i.e. the
house supply box)
N and PE are connected together in the house supply box, so from there
on they are five leads going to the measuring device, fuse boxes and
distribution of the house. This widely distributed local grounding
ensures also the centering of the supplier's distribution network.
Depending on the load situation, there may a few volts difference
between N and PE.
- Green and yellow is always earth = ground labelled PE, protective
earth), e.g connected with the water pipe, a special ground anchor, the
steel armour in concrete foundations or a foundation ground lead.
Green/yellow wire may not be used for anything else except for tieing
potato sacks!
- In general, blue is neutral, but may carry other potentials also if in
shortage of more colors, labelled N.
- Formerly, grey was used for N (beware of old installations!)
- Black is the most dangerous color: permanent live in alternating
current circuits, labelled P or Ph or P1, P2, P3, or L, L1, L2, L3
- Brown can also be permanently live, but is preferably used for live
(phase) in switched circuits, i.e., may be live or not, you may have a
chance to live
- In three phase systems - the most commonly applied supply system in
today's houses - the three phases are brown, black, black (rarely grey).
The latter can be switched to achieve correct field rotation without
offending the wiring schematic.
- All other colors may be used for various purposes, preferably for
momentary relays, alternate switch circuits or machine outputs. I use
violet and green to activate impulse relays e.g. in staircases etc.
- In very old installation, PE was red, sometimes also later, especially
in Switzerland
- Industry is adapting these colors increasingly for the inside wiring
of electrical devices, too
So, keep away from brown or black wires and have care with blue ones!
And remember what I learned in my electricity courses in the US: -
Always keep one hand in your pocket when dealing with live appliances,
- only use the monkey grip (without the thumb being involved) and
- if there is no chance to grab a measuring device first, test first for
live appliances with the upside of your finger (there they are drier)!
Best regards
Peter
Am 12.05.2022 um 11:50 schrieb andy pugh:
On Thu, 12 May 2022 at 06:31, Philipp Burch <p...@hb9etc.ch> wrote:
I could imagine that the colors are due to the usual coding (at least in
Europe) for AC circuits with brown=Phase (hot wire) and blue=Neutral
(cold wire).
UK fixed household wiring used to be red for live and black for neutral.
Then three-phase was red-blue-yellow with black neutral.
In 2006 we harmonised with Europe, so that it is blue neutral, brown
live and three-phase is brown-black-grey with a blue neutral.
So, now when you find a wire:
green/yellow - always earth
black - live or neutral
blue - live or neutral (already the case before harmonisation)
brown - live
red - live
yellow - live
grey - live
In fairness, appliance flex has always been brown-live blue-neutral
for as long as I have been wiring plugs, so it makes sense for the
fixed wiring to match. But the colour choice for 3-phase seems odd.
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