Brown sleeving of G/Y core of flex

[JohnW2]

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.

 

[ban-all-sheds]

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

You're a very naughty boy.

 

[JohnW2]

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

You're a very naughty boy.

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.

 

[Spark123]

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.

 

[JohnW2]

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.

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.

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

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."

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.

 

[JameZZ]

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?

 

[Spark123]

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.

 

[JohnW2]

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.

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?

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.

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.

 

[riveralt]

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?

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

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.

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.

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).

Having the CPC there is very handy for test purposes.

 

[RF Lighting]

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.

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?

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)

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.

 

[JohnW2]

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.

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!

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

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.

 

[securespark]

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

 

[JohnW2]

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.

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.

 

[JohnW2]

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

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.

 

[mfarrow]

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.

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]"