Wire Color Codes

[mtdoc]

It's particularly confusing here in the USA when working on PV systems where you are often transitioning back and forth between DC (black negative, Red Positive) and AC, where black is "live" and white is "neutral" and usually tied to earth ground.  Code specifies bonding DC battery negative to earth ground - further confusing things.

[Jeroen3]

I can understand that the negative of a DC circuit is tied to ground at the battery since AC Neutral is also tied to ground at the transformer.

[SL4P]

The mashup described in the preceding comments - explains why mains wiring should be done by a locally licences electrician!

For ELV projects, I stick with
Vas/0V/GND black
+5Vcc red
+12V yellow
then I start looking for 'as close as I can' standards...

[Dave Atom]

Red to Red,
Black to Black,
Plug it in,
And stand well back.

Always worked for me

[Zero999]

The plate pictured below is not one of mine and I only grabbed it for the rotary switch and sometimes you just have to deal with what the fellow that went before you did, in our industry we deal with a wide variety of multicore cables and there are some adopted practices but we never take it for granted that someone else does the same.

It might be the black wire ?.......

If you look closely, the cable cores are numbered which is quite common in multicore cables.

There is no standard for the colour of wiring inside appliances, whether it be AC or DC, regardless of the voltage.

Not quite true - IEC61010 specifies that earth is only on Green / Yellow wire, and the wire should not be used for anything that is not earth.

That doesn't apply to domestic/office equipment though, so something like a PC could use any colours.

I don't have access to the standard you've referenced to but EN60204 says:

Black = AC or DC power
Red = AC control
Blue  = DC control
Orange = safety
Green & yellow PE and nothing else, which agrees with you.


Link:
http://www.yuntongglass.com/upfile/2012031917030348602.pdf
Pages 76 & 77.

[dom0]

I'm pretty sure the IEC standard says that green-yellow must only be used for PE, independent of context.

[richard.cs]

But, honestly, why the Europeans chose blue for "neutral" and brown for "hot" is even more bizarre and arbitrary, IME. Even as I write this I wouldn't bet my life that is correct because it just seems so completely random.

It's the compromise you get when trying to select colours that aren't ambiguous when mixed with the many different previous systems across multiple countries. Blue had never been a phase colour in single phase systems (but had been L3 in the UK) so it was a reasonable choice. Brown is a bit worse, it was earth in the UK though not for long (1934-1939). Red had been used for just about everything, as had black. But the blue/brown combination hadn't been used anywhere before. Black L2 and Grey L3 were the result of the UK pushing for different phase colours, in much of Europe it's normal to use 1 phase colour and a rotation tester (which is usually good enough but doesn't get you absolute phase).

Personally I liked the old UK system with the three primary colours as the three phases, it seemed reasonably logical and with colours for phases black follows as a sensible choice for neutral.

[Zero999]

Personally I liked the old UK system with the three primary colours as the three phases, it seemed reasonably logical and with colours for phases black follows as a sensible choice for neutral.

Me too. There was no need to standardise with the EU for fixed wiring. I can understand the need for equipment exported to the EU but the colour of the wires, in buildings here in the UK, is none of their business

[LaurentR]

Even though a lot of car OEM harnesses use totally random colors, basic car audio aftermarket harnesses are fairly standard (Metra/EIA).
http://www.the12volt.com/caraudio/headunitharness.asp

Memory / Constant 12V(+)   Yellow
Switch / Accessory   Red
Ground   Black
Illumination   Orange/White
Antenna Remote   Blue
Amp Remote   Blue/White
Left Front (+)   White
Left Front (-)   White/Black
Right Front (+)   Grey
Right Front (-)   Grey/Black
Left Rear (+)   Green
Left Rear (-)   Green/Black
Right Rear (+)   Violet
Right Rear (-)   Violet/Black

[retrolefty]

It can be very disheartening the lack of standards sometimes. At the refinery I worked at the various plants, maybe a dozen, each had a different central control house with many many 4-20ma 50 pair cables running from house to plant instruments and valves. 50 pair twisted shield white/black was the most frequent cabling used. However some plants used white for the +24 loop power and black for the loop common/ground. At the next plant it would be the opposite. It came down to when the plant was built which project 'standards' were used. Best to always measure over assuming. Kind of a measure twice cut once thing.

[ROBOT]

Not really a standard but whenever working with low voltage stuff black is almost always ground and red would be +5v. I tend to use orange for 3.3v.

[N2IXK]

Back in the vacuum tube era there was a RETMA standard color code for internal wiring of electronic gear:

Black - Grounds, grounded elements and returns
Brown - Heaters or filaments, off ground
Red - Power Supply B-plus
Orange - Screen grids
Yellow - Cathodes
Green - Control Grids
Blue - Plates
Violet - not used
Gray - AC power lines
White - Above or below ground returns, AVC, etc.

[Cerebus]

Personally I liked the old UK system with the three primary colours as the three phases, it seemed reasonably logical and with colours for phases black follows as a sensible choice for neutral.

Me too. There was no need to standardise with the EU for fixed wiring. I can understand the need for equipment exported to the EU but the colour of the wires, in buildings here in the UK, is none of their business

The argument would be:

1) Free mobility within the EU. If you're an electrician it lets you move between EU countries more easily.
2) Market equalities. If you make cable in the UK you can sell the same cable in France, Germany etc. etc. You only have to meet one set of regulatory requirement for the whole EU, rather than one for each country. I've noticed that people are starting to specify cables by european type numbers rather than the UK IEE/BASEC numbers, which used to be standard practice in the UK. (e.g. H07V-R instead of 6491X)