3 core and earth cable colours

On Tue, 15 Jul 2008 14:15:14 +0100 someone who may be "Dave Plowman (News)" wrote this:-

Nothing idiosyncratic, professorial or ivory tower about it. Using blue, sleeved black was looking forward. Using black, sleeved blue, is looking back.

Reply to
David Hansen
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On Tue, 15 Jul 2008 11:47:46 +0100 someone who may be John Rumm wrote this:-

Rather more than its normal purpose. Green/yellow insulated conductors are not permitted to be used for any other purpose, even if sleeved/labeled accordingly.

Reply to
David Hansen

Invariably use?

Reply to
Tony Bryer

It is indeed looking forward. I know of no electrician that uses the black for neutral on a 3 core and earth cable. I believe it was done this way as the colour changes were Red>Brown, Yellow>Black, Blue>Grey and Black>Blue on three phase when the colours changed.

I suspect that blue became the obvious choice to use as the neutral in old colour wiring as blue was already used on flexes as a neutral, and on 3 core armoured cable (using a core for earth) the yellow is closer to the green/yellow for an earth. I wonder if Andy Wade knows a reg for this?

Yellow is very rarely seen as the neutral in old colours (and Mr Plowman knows that :-) ) but in the future black will not be seen as the neutral in the new colours.

Adam

Reply to
ARWadworth

I think the red yellow and blue phase colours well predated the harmonised flex colours.

Black is still used as ground/negative on lots of things. Battery radios etc. So most will think of it as negative. So why complicate the issue?

Reply to
Dave Plowman (News)

I'll bet it will with 99% of DIYers using it for thermostats etc.

Reply to
Dave Plowman (News)

Yep. Diagon Ally.

We cheat & use white with L1, L2 & L3 labels now. Boring. :-(

Reply to
mick

Stupid b***y colours anyway. The idiots that chose them had obviously never tried to trace partially burned wiring "singles" in a floor space, dis board or control panel by the light of a pen torch held between the teeth!

Incidentally, Neutral is officially light blue. Control panels (usually those sourced in the US) tend to use dark blue for DC control supplies.

Reply to
mick

Reply to
John

Because it is very definitely a phase in a three phase system.

Reply to
John Rumm

And meter leads: they aren't going to change.

Negative is not neutral and I think it's probably the case that, in the context of building wiring, black now means line/live/phase in almost every country of the world.

Grey core for neutral seemed to me to be the obvious choice, even before I saw it recommended somewhere.

Reply to
Andy Wade

It might be in IEC-land or some product or panel wiring standards, etc. but that hasn't come through to BS 7671 which just says "blue".

Reply to
Andy Wade

So is grey.

Reply to
Bob Mannix

Actually, having done some more reading, the use of black for neutral is deprecated not, as John said, because it is a phase colour in a three phase system (so is grey as I said) but because, sur le continent, both black and brown are used for live/phase (and blue for neutral), so grey is more harmonious in an EC sense as we move forward and the confusion with existing wiring systems was felt not to raise immoderate safety issues. It's a bit hypothetical in the OP's second instance as all three conductors are live at some point!

Reply to
Bob Mannix

Indeed, but grey does not appear in the old colour scheme, so there is no chance of confusing its meaning.

Reply to
John Rumm

(thought you'd say that :o) ) yeah but no but... blue was a phase colour in the old scheme and no problem using that as neutral... so I think my other post pertains

Reply to
Bob Mannix

Obviously, to prevent confusion, we need some brand new never-seen-before colours... :-)

Reply to
Rod

As there appears to be no rhyme (or reason) perhaps we should use the three words in the english language that have no words that rhyme with them (as they are all colours) - orange, silver and purple. Think I'll go back to the home now....

(there, that's set you all thinking)

Reply to
Bob Mannix

Curple. Chilver.

And...

The four eng- ineers Wore orange brassieres.

Reply to
Rod

Scottish dialect - doesn't count!

Archaic - doesn't count!

Cheater!

Reply to
Bob Mannix

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