Brown sleeving of G/Y core of flex

I may have dreamed it, but I seem to remember reading somewhere of a specific prohibition of sleeving the G/Y core of 3-core flexible cable with brown (or red in very old colours) and using it as a live conductor. Is that true and, if so, where is it that I read that?

I must confess that I have done this in my time. Whilst I suppose one can just about understand the thinking behind such a prohibition (if it exists), it could be a bit of a nuisance. There are situations (e.g. with sensors such as PIRs) where one needs N, L and S/L but, since the device is Class 2, not a CPC. In such a situation, it seems to be a bit daft to have to move to 4-core cable simply to avoid using the G/Y core of 3-core cable, particularly since one then has an unused G/Y core for which there may well be no provision for termination at the device end.

Kind Regards, John.

JohnW2 said:

I must confess that I have done this in my time.

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You're a very naughty boy.

ban-all-sheds said:

JohnW2 said:

I must confess that I have done this in my time.

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You're a very naughty boy.

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Well, if that were the naughtiest thing I'd ever done, I would probably sleep better at night!

Anyway, do you know where it is written that I've been naughty - since, as I implied, I can no longer find it?

The irony, of course, if I could find some 3-core cable with non-standard colours, I guess it would be OK to use it (with appropriate sleeving or alpha identification), provided only that none of the colours was G/Y!

Kind Regards, John.

Daft as it sounds, you still need to run a CPC to each accessory where protection is by ADS, regardless of wether it is class 1 or 2. The arguament being, what would happen if someone replaced the accessory with a class 1 accessory.
I think regulation 514.4.2 prohibits the oversleeving of G&Y protective conductors as you propose.

Spark123 said:

Daft as it sounds, you still need to run a CPC to each accessory where protection is by ADS, regardless of wether it is class 1 or 2. The arguament being, what would happen if someone replaced the accessory with a class 1 accessory.

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Yes, it does sound a bit daft. If that sort of 'future-proofing' philosophy were extended to other situations, you'd probably be putting in massive cables for even modest-powered showers and cookers, 'just in case' someone subsequently replaced with a higher-powered appliance. Perhaps more seriously, I'm not sure that the concept of introducing a CPC into a Class 2 accessory is necessarily all that good an idea, particularly if there is no provision for terminating it - usually resulting in it 'being left lying wround' within the accessory, probably attached to a little bit of connector strip.

Spark123 said:

I think regulation 514.4.2 prohibits the oversleeving of G&Y protective conductors as you propose.

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Ah, yes, that's what I was thinking of - so at least I wasn't dreaming! Thanks. However, on now reading it again, I wonder if it actually is saying what we think. The only bit really relevant bit (for multi-core cables) is the first paragraph, which reads:

"The bi-colour combination green-and-yellow shall be used exclusively for identification of a protective conductor and this combination shall not be used for any other purpose."

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So, it's saying that I must not use G/Y colours to 'identify' something which is not a protective conductor. However, that is not what I'm talking about. The conductor would be 'identified' (at both terminations) by brown sleeving (and that could even be done in such a manner than none of the G/Y was even visible).

It's different for single core cable. The next paragraph specifically prohibits the over-marking of single-core G/Y (except for PENs), but there is no similar statement about the G/Y core of a multi-core cable.

I'm therefore now left wondering! If one takes that first para of 514.4.2 literally, one could easily argue that to do as I described would be acceptable, provided that the core was 'identified' with brown sleeving. However, that would not alter what you said above, about the requirement to run a CPC to a Class 2 accessory - so I guess we're probably stuck with 4-core cable, anyway!

Kind Regards, John.

When we had a new heating system installed a few months ago, they used 3 core flex to connect the cylinder stat to the control box next to it, using g/y as a live sleeved in brown, so is that strictly speaking wrong then?

The term, rough as a badgers backside springs to mind!
I would never use a G/Y protective conductor for any other purpose that what it is intended for.

It is only viable to not run a CPC to an accessory providing there are additional providisions in place so that nobody will ever replace it with a piece of class 1 equipment, such as supervised locations.

Spark123 said:

The term, rough as a badgers backside springs to mind!
I would never use a G/Y protective conductor for any other purpose that what it is intended for.

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Fair enough - but I presume that you regularly use a blue-insulated neutral conductor (with appropriate sleeving) for a purpose other than what it is intended for, don't you? Is it really all that different?

Spark123 then said:

It is only viable to not run a CPC to an accessory providing there are additional providisions in place so that nobody will ever replace it with a piece of class 1 equipment, such as supervised locations.

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This seems to be the compelling part of the argument. As I said, it is quite possible to read 514.4.2 as permitting the use of a G/Y insulated core asa live conductor, provided it is identified as such with brown sleeving. However, you are indicating that, with few exceptions, a 4-core cable is needed, anyway (even though the CPC remains unconnected at the accessory end) - in which case the colour issue goes away.

Are you totally happy with a CPC being introduced into a Class 2 accessory, even if it is not connected? (the manufacturers' instructions for some Class 2 accessories which need just L & N specifically say that one should not use 3-core cable to connect them).

Kind Regards, John.

JohnW2 said:

Fair enough - but I presume that you regularly use a blue-insulated neutral conductor (with appropriate sleeving) for a purpose other than what it is intended for, don't you? Is it really all that different?

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But isn't that convention and what you might/should expect at the switch plate and the ceiling rose.

JohnW2 said:

This seems to be the compelling part of the argument. As I said, it is quite possible to read 514.4.2 as permitting the use of a G/Y insulated core asa live conductor, provided it is identified as such with brown sleeving.

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Again I would say it is a convention thing - probably less of an issue with cable where cpc is the same size as the live conductors but certainly an issue where the cpc is smaller than the live conductors - we have to start to fuse down to the lowest common conductor denominator.

To me it is too much hassle - and a sign of poor workmanship - better to use the standard configuration than make your own up.

JohnW2 said:

Are you totally happy with a CPC being introduced into a Class 2 accessory, even if it is not connected? (the manufacturers' instructions for some Class 2 accessories which need just L & N specifically say that one should not use 3-core cable to connect them).

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Having the CPC there is very handy for test purposes.

JohnW2 said:

Spark123 said:

The term, rough as a badgers backside springs to mind!
I would never use a G/Y protective conductor for any other purpose that what it is intended for.

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Fair enough - but I presume that you regularly use a blue-insulated neutral conductor (with appropriate sleeving) for a purpose other than what it is intended for, don't you? Is it really all that different?

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Yes it really is very different.

The blue conductor is designed for use as a live conductor whether that be line, neutral, switched line etc.

A green and yellow conductor is not designed to be used as a live conductor and it should never be used as such.

Are you totally happy with a CPC being introduced into a Class 2 accessory, even if it is not connected? (the manufacturers' instructions for some Class 2 accessories which need just L & N specifically say that one should not use 3-core cable to connect them)

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Yep totally happy.

They say that you should not connect an earth to the equipment. They do not say you must not supply the equipment with a 3 core cable with an earth terminated in a seperate connector.

riveralt said:

Again I would say it is a convention thing - probably less of an issue with cable where cpc is the same size as the live conductors but certainly an issue where the cpc is smaller than the live conductors - we have to start to fuse down to the lowest common conductor denominator.

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Yes, I agree it's a matter of convention - and, as I've said arguably not compulsory per the regs. Maybe "I haven't lived", but I can't recall having come across a flexible cable that didn't have all conductors the same size. One obviously couldn't use the bare CPC of T&E as a live conductor, even if one sleeved it at the terminations!

riveralt said:

To me it is too much hassle - and a sign of poor workmanship - better to use the standard configuration than make your own up.

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I agree. I think when it's done (seemingly not uncommonly), and on the few occasions I've done it, it's been primarily because no 4-core cable was to hand at the right moment.

Kind Regards, John.

Imagine hacking into a cable in the loft and connecting something to it, expecting the GY core to be earthed.....

RF Lighting said:

Yes it really is very different.
The blue conductor is designed for use as a live conductor whether that be line, neutral, switched line etc.
A green and yellow conductor is not designed to be used as a live conductor and it should never be used as such.

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Fair enough, and it's certainly convention. I peesonally think it would become fairly academic if it was sleeved at both ends such that no G/Y was visible anywhere (unless someone cut the cable!), but I suppose there is something to be said by taking a Jobsworth approach.

Kind Regards, John.

securespark said:

Imagine hacking into a cable in the loft and connecting something to it, expecting the GY core to be earthed.....

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Yes (having just written in another post "unless someone cuts the cable"), I take your point.

Mind you, the person hacking into a T&E cable in a loft and connecting something to it, expecting the blue core to be neutral could also get a surprise in some cases - maybe twin brown should be compulsory for switches, and the brown-sleeving of blues banned?

Kind REgards, John.

JohnW2 said:

This seems to be the compelling part of the argument. As I said, it is quite possible to read 514.4.2 as permitting the use of a G/Y insulated core asa live conductor, provided it is identified as such with brown sleeving.

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In what way is this possible?

From 514.4.2:
"Single-core cables that are coloured green-and-yellow throughout their length shall only be used as a protective conductor and shall not be over-marked at their terminations, except as permitted by Regulation 514.4.3 [PEN conductors]"