I´m looking for a international standard that define electrical color codes to be used in low voltage power distribution cables in a three phase system.

I´m interesested in particular in verify if there standards that defines the colors of grounding cables.

Well,
Emilio, I think that you may have just found the right place for this!.
We had a whole host of posts here a wee while back on this very subject.
Hey, and must say that you are the first to post from Brazil there mate, but we are all in the same boat here, just trying to learn more.
I'll just go and have a look for you!.

thanks.

The standard of wire grounding color has become a polemic issue in my company last week.

Im happy to find a helping hand.

OK Emilio,
Just click on the link below:
https://www.electrical-contractor.net/ubb/Forum15/HTML/000077.html
Scott35, another of our Moderators, has done a really cool job of presenting it all!.
Hope that this helps.
And please, feel free to peruse and reply to the other topics in the Board here, you're more than welcome to, you know!.

thanks a lot.
Ill be try to share with our mates.
thanks again.

Hey Emilio,
What Voltage do you guys use?

In my plant we usually are using
13,8kV 3Ph
4,16kV 3Ph
0,46kV 3Ph
220/110 1Ph (grounding and neutral coming from the center of the secondary of the distribution transformer.

For while, I'm worried about the 0,46kV system but it's important to remember the rest of the electrical distribution system.

Hello Emilio, and welcome to ECN.

It's quite intriguing the way that different color code standards developed over the years. Those of us who grew up in English-speaking countries always associate green with grounding conductors, and the thought anyone could have used anything else seems very strange (we've just about got used to green with yellow stripes now ).

Click here to see the discussion which led to the posting in the reference area.

Hi new to this forum but i have a question about regulations for DC colour coding in the UK.

My understanding is that the norm is to use Red /Black is this correct ?

Darren Butts

Darren,
Welcome to ECN, mate!.
The answer to this question depends upon where you are installing the DC equipment.
With Panel boards, this can mean anything apart from Red and Black, where the 240V wires use this coding.
We have codings here of Violet, Orange or Grey.

Hi Darren, and welcome to another fellow Brit!

Most people here associate red and black with positive and negative respectively of a DC circuit, but there are variations.

In the days when DC mains supplies were still around in Britain, the IEE specified the following:

Positive of 2-wire circuit => Red
Negative of 2-wire circuit => Black

Positive of 3-wire circuit => Red
Neutral of 3-wire circuit => Black
Negative of 3-wire circuit => Blue

Outer (positive or negative) of a 2-wire circuit derived from a 3-wire system => Red

In the typical residential street where half the houses were fed from the positive side of a 3-wire DC system and half from the negative side, it meant that for the latter houses the red would actually be the (live) negative, with black as the (earthed) positive.

The IEE specification of blue for a live negative wire in a 3-wire circuit dates back only to 1966. Prior to that, they specified that the 3-wire negative be yellow or white, (i.e. the same color as the second phase of a 3-phase AC system.)

When the European colors were adopted for flex around 1970, the IEE then specified that flex carrying a 2-wire DC circuit should use brown for positive and blue for negative, in line with AC systems.

The use of red and blue coding for conductors positive or negative with respect to ground was, and indeed still is, found in other areas.

For example, in British telephone exchanges the supply busbars (which are at -50V with respect to earth) are generally identified with blue.

Look on the London Underground and you'll see the feeder equipment at the side of the track identified with red for the positive (outer, +420V) conductor rails and blue for the negative (center, -210V) rails.