Replacing light - House that jack built!

[JohnW2]

I can only assume part of Europe was using yellow as earth and part using green Which is why we ended up with 2 colours for earth?

An interesting theory - maybe correct. Another possibility, thinking of stillp's comment, is that the two-colour stripes are probably more immediately identifiable (than would be any single colour) by those with a range of colour vision defects.

Seeing how the world has evolved, if the system were being invented today, we'd probably end up having distinct 'stripe patterns' for each conductor (so that there was no reliance on colour vision at all), and maybe also Braille markings (for those who had no vision at all, but nevertheless were engaging in electrical wiring ).

Kind Regards, John

 

[Astra99]

I seem to recall that the primary reason for the green/yellow colouring for the earth flex was to make it easier for those with red/green colour blindness to identify the earth.

The old solid green and solid red colours, according to research at the time, looked identical to those with red-green colour blindness, so a means of readily identifying the earth core was used. By all accounts, brown is more easily identifiable than red for the colour-blind.

I do think it was gross stupidity to use black as a phase colour in the "new" system. Because of the use of blue as neutral in flexes, I can just about accept blue as neutral, but solid black as a phase colour? This will certainly require VERY careful marking in three-phase boards, or even where two-way switching or live-switched live-neutral is involved and mixed colours. BTW, which core of brown-grey-black is recommended for use as the neutral? I tend to use black, simply because black was neutral (and sleeve it blue).

Why the colours were not solid brown, brown with grey tracer and brown with black tracer I do not know. That way any confusion with old colours would be eliminated.

 

[JohnW2]

I seem to recall that the primary reason for the green/yellow colouring for the earth flex was to make it easier for those with red/green colour blindness to identify the earth. ... The old solid green and solid red colours, according to research at the time, looked identical to those with red-green colour blindness,

Sounds very credible - as I wrote:

Another possibility, thinking of stillp's comment, is that the two-colour stripes are probably more immediately identifiable (than would be any single colour) by those with a range of colour vision defects.

I do think it was gross stupidity to use black as a phase colour in the "new" system. ...

As I've said, it's (IMO) very far from ideal.

BTW, which core of brown-grey-black is recommended for use as the neutral? I tend to use black, simply because black was neutral (and sleeve it blue).

I think the most common guidance is to use the grey, not black, in the hope that this will help to break the subconscious association that many have been black and neutral! Of course, provided it is sleeved blue, one can use any as neutral (even the brown!) and still be compliant.

Why the colours were not solid brown, brown with grey tracer and brown with black tracer I do not know. That way any confusion with old colours would be eliminated.

It will obviously never happen, but I couldn't agree more. Furthermore, as I said, if the width/pattern/whatever of those tracers was made distinctive, it would still work for people with no colour vision at all.

Kind Regards, John

 

[AndyPRK]

This is the problem. Some people use black and some grey for neutral.

 

[JohnW2]

This is the problem. Some people use black and some grey for neutral.

I'm not sure I'd call it a problem - as I said, either is 'clear' (and compliant) provided it is over sleeved with blue.

As I said, the reason some (many?) people favour using the grey is in an attempt to 'un-educate' people's brains as regards the traditional association between black and neutral.

Kind Regards, John

 

[AndyPRK]

So if a cable has two lives and a neutral
You would use grey as neutral
And black as a live ?

I guess it's no worse than 3 phase.

 

[JohnW2]

So if a cable has two lives and a neutral
You would use grey as neutral ... And black as a live ?

Yes, but if it's single-phase, then the black would presumably be over-sleeved brown (and grey over-sleeved blue).

Kind Regards, John.

 

[mfarrow]

Don't be so daft. If it's single-phase L, N & E.

You oversleeve the Black as Brown.
You oversleeve the Grey as Green/Yellow.
You oversleeve the Brown as Blue.

That way nobody can ever get any preconceptions in their heads regarding cable colours being sleeved in any way to reflect 'what they're used to'.

...

Sorry I'm just being wound up. If you can't identify the conductor by cable oversleeving and get confused because you once saw a cable that colour identified as a different conductor then you should not be undertaking work on electrical installations!

 

[JohnW2]

Don't be so daft. ...... Sorry I'm just being wound up. If you can't identify the conductor by cable oversleeving and get confused because you once saw a cable that colour identified as a different conductor then you should not be undertaking work on electrical installations!

Don't shoot the messenger! I essentially agree with what you say - and have already said that it would be perfectly acceptable, and compliant, to oversleeve the brown with blue for use as neutral (and oversleeve one or both of the other conductors with brown for use as line).

I have merely been 'passing on' my understanding of the reason why many people seem to favour the use (with blue oversleeving) of grey, rather than black, as neutral.

I'm not actually sure why you're getting so excited, since (if one doesn't invoke that 'psychological' reasoning) it's an arbitrary decision - and once one has decided to 'forget old colours', it's no more logical to use black than grey (or vice versa) for neutral (with blue oversleeving).

Kind Regards, John

c

 

[conny]

When I worked in Liverpool we had 2 contractors arrive on site to connect a compressor in an out building.
One guy connected up to the isolator in the outbuilding while the other guy connected up to the breaker panel in the factory. Clearly they did not communicate with each other or test the installation before leaving. One of the lads in the workshop switched the compressor on the following morning and tripped the breaker. On investigating it was discovered they had used old colour SWA consisting of red, yellow, blue and black. (You know whats coming don't you?)

The guy in the outbuilding had connected black as the neutral while the guy in the factory had connected, (and sleeved it), as a phase and used the blue as the neutral. Needless to say they were asked to return, at their company's expense, and rectify and test.

 

[ban-all-sheds]

You know whats coming don't you?

Is it an attempt to say that the problem was caused by the colour change rather than the bumbling incompetence of the 'electricians'?

 

[JohnW2]

You know whats coming don't you?

Is it an attempt to say that the problem was caused by the colour change rather than the bumbling incompetence of the 'electricians'?

Probably not - but it is an example of an error that even bumblingly incompetent 'electricians' would presumably not have made in the absence of the change. In the example given, the most unforgivable thing is, IMO, not the wiring error, per se, but the failure to detect it before leaving the site.

Kind Regards, John

 

[mfarrow]

Don't shoot the messenger!

John, my post was not aimed at you. I think I was getting wound up because there are electricians out there who will believe oversleeving is to be done a particular way every time and therefore run an increased risk of being caught out at some stage by something which is different to the perceived best practice. There will additionally be those who lack the technical understanding of this his forum not to cry foul upon such discoveries, either to the cost to them or their customers.

In an ideal world I suppose all cable cores would be identified by a neutral colour (whatever that would be) and each core tested through between terminations. The oversleeving would then be mandatory and the discussion irrelevant. Whether anyone would want to pay for the additional labour or not is a different question...

 

[JohnW2]

John, my post was not aimed at you. I think I was getting wound up because there are electricians out there who will believe oversleeving is to be done a particular way every time and therefore run an increased risk of being caught out at some stage by something which is different to the perceived best practice.

Fair enough. However, I'm not sure what alternative there really is. It's not that uncommon for people to ask (here and in other places) whether they should use black or grey for oversleeving as neutral. They usually get answers (with or without 'explanations') based on what the individual responders regard as 'better' (or, at least, their personal 'standard practice'). Are you suggesting that, rather than be given explicit answers(s), people who ask the question should be told 'to toss a coin'?

Kind Regards, John

 

[JohnW2]

Change is an inevitable and necessary fact of life.

Indeed so - and the harmonised colours are with us, and have to be accepted by us, and will probably be with us for a very long time - so certainly no point in anyone whinging.

It would (IMO) just have been nicer ('safer', certainly initially) if the harmonised conductor identifications had been created in such a way that there were not 'contradictory overlaps' with the identifications previously used in all the countries concerned. That may not have been possible with single colours alone - but, as I've said, there's something to be said for 'stripes' etc. (they did it for G/Y).

Kind Regards, John