Poll: Over-sleeving Harmonised 3C+E Cable

sparkwright said:

Since the heading of this poll is simply asking for the PREFERRED, not compulsory, colour of a neutral on a harmonised 3 core+e ...

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That's what I had to ask about since (unless I'm missing something) there is nothing 'compulsory' involved. , I would urge anyone who voted the third or fourth option to change their vote, and vote for which colour they choose to use, based on logic and personal preference.[/QUOTE]Yes, that would be interesting, but it's a different question from the one I was asking. I was expecting that if people voted, a significant proportion would say that their normal practice "varied", either "just because it varied" or because it depended upon other features of the installation.

In passing, I wonder what happens in countries (we keep being told that there is at least one) where over-sleeving is not allowed? Do they have the likes of 'triple brown+E" for lighting strappers and "twin brown + blue + E" for the sort of thing being discussed in this thread - or do they use singles or multiple multicore cables?

Kind Regards, John

If you had two three cores, one with 3 line conductors (two switched and one permanent live) and one with two switched line conductors and a neutral, which colour would you use for each?
I understand they would be over-sleeved if necessary, but would your logic choose a particular colour?

securespark said:

If you had two three cores, one with 3 line conductors (two switched and one permanent live) and one with two switched line conductors and a neutral, which colour would you use for each? I understand they would be over-sleeved if necessary, but would your logic choose a particular colour?

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I was really interesting in fin ding out what electricians thought about the situation I described (one L, one S/L and one neutral). However, as for what I would personally probably do in the situations you describe ...

(a) ... (which is the situation with the 'conversion' method of 2-way light switching). This one is simple, and I would think 'logical'. I would (I would say 'obviously') use brown as the permanent live, and it clearly wouldn't matter about the two S/Ls.

(b) ... (which is the common situation with the 'traditional' method of 2-way light switching). For me, this is also simple, since I would want consistency with my other practices. In the (L, S/L, N) situation (i.e. per this thread/poll) I would, as I have said, use the grey as neutral (as, seemingly, would most people who have so far 'voted'). To remain consistent with that, I would again use grey as neutral in the scenario you describe - and, again, it clearly wouldn't matter about the two S/Ls.

Do you regard that as 'logical'?

I think I now have to throw this one back at you - what colour choices would your 'logic' make in those two situations?

Kind Regards, John

Well, of course, it all depends on which colours you habitually use. I used to use red (brown) for common and yellow/blue (black/grey) for strappers, but I know that some use yellow/ black for the common. In this situation if the two switched lines in my example were strappers, logic could be tempted to keep the same colours (yellow/blue or black/grey), and sleeve the red/ brown as neutral.
If you apply the "other" logic, you use blue/grey for the neutral and are left with red/yellow or brown/black for the strappers.

Now, in my example circuit that I showed you in another thread (about eddys https://www.diynot.com/diy/threads/eddys.500801/), if you were running both those cables to the same box, you might want to do it the first way, as then both pairs of strappers would be the same colours.

securespark said:

... In this situation if the two switched lines in my example were strappers, logic could be tempted to keep the same colours (yellow/blue or black/grey), and sleeve the red/ brown as neutral.

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I don't think I would do that. If one of the conductors was a permanent L, I think I would use brown for that. In fact, I can't recall ever having over-sleeved a brown conductor with blue (or a red conductor with black) - since I might find that confusing!

securespark said:

If you apply the "other" logic, you use blue/grey for the neutral and are left with red/yellow or brown/black for the strappers.

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That's what I would probably do.

securespark said:

Now, in my example circuit that I showed you in another thread (about eddys https://www.diynot.com/diy/threads/eddys.500801/), if you were running both those cables to the same box, you might want to do it the first way, as then both pairs of strappers would be the same colours.

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Yes, some might think that way. Speaking personally, I would prefer to stick to my personal convention that a permanent L is always brown and a neutral is always grey - although I agree that would mean that the 'strappers' would be different colours in the two cables.

Kind Regards, John

sparkwright said:

You only have to look at installations done before 2004 to know this is a fact, on a 3 core+e cable blue would be used as neutral.

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I wasn't denying it - I was asking why

More than 99% of the time, blue would be used, I would estimate. I don't know why.

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It can't be because blue was the N colour in flex, because that was a different system.

If one were talking about L, S/L, N, then, in pre-harmonised days, red was 'obviously' L. Of the other two (yellow and blue), I think that the great majority of people would have perceived yellow as being more of a 'danger colour' than blue, hence were inclined to use that at the S/L, leaving ('co-incidentally', in view of flex colours which appeared) blue as neutral. I certainly don't recall ever having seen yellow used as neutral.

So do you think anybody would have quibbled then with guidance to use blue, sleeved black, as the neutral?

ban-all-sheds said:

It can't be because blue was the N colour in flex, because that was a different system.

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Maybe, but that was my logic. The blue was neutral in flexes, hence I sleeved the blue in cable with black and used it as such.

I wrote that as a reference to this:

sparkwright said:

They misguidedly think because black always used to be neutral, then they should use the new harmonised black as neutral.

But the two systems are different.

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securespark said:

Maybe, but that was my logic. The blue was neutral in flexes, hence I sleeved the blue in cable with black and used it as such.

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Fair enough - but, as I recently wrote, even before flex colours changed (i.e. before there was any association between neutral and blue), I would probably still have used the blue (sleeved black) - since, as I said, red and yellow are the two colours (of the three) which most 'intuitively' have an association with 'danger' - hence most logically used for the line (L & S/L respectively) conductors.

Kind Regards, John

JohnW2 said:

In passing, I wonder what happens in countries (we keep being told that there is at least one) where over-sleeving is not allowed? Do they have the likes of 'triple brown+E" for lighting strappers and "twin brown + blue + E" for the sort of thing being discussed in this thread - or do they use singles or multiple multicore cables?

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I can tell you about Austria and Germany. Neither country uses a direct equivalent to 3C+E since all CPCs are required to be full-sized and insulated. If a neutral is required it has to be identified blue along its entire length unless none of the cores are coloured (most building cables with more than five cores have black cores with printed numbers and a green/yellow CPC) so 4C is really only suitable for applications that require no neutral. The first round of harmonisation back in the mid-60s had 4C with a blue conductor (green/yellow, black, blue and brown) so things were different at that time. These days 5C is much more common and due to the large volumes often cheaper than 4C so that's what people use. There are no prescribed colours, although it's suggested to use brown as live and black and grey as switched live or strapper. Older sparks prefer black for live. Immediately after the introduction of the new colours it was somewhat common in Austria to oversleeve grey and use it as a neutral in Austria but I'm not sure on what basis - the regs aren't quite up-to-date on that. I suppose the paragraph "conductors may be re-idientified if no cables with the appropriate core colours are manufacured" could apply although it was probably meant to refer to the cables with more than five cores.

If we're talking about a simple switch loop rules differ between Austria and Germany. Germany allows you to use the blue core without oversleeving while Austria doesn't - you'd have to use 4C or 5C even for that. Has the additional benefit of being able to install a socket below the switch - we don't necessarily separate lighting and socket circuits although some consider it good practice. In domestic indoor wiring most Austrians use singles in flexible conduit (corrugated tubing), commonly black for live and orange or purple for switched live.

The regs in both Austria and Germany are fairly relaxed on core colours for live conductors - basically any colour but yellow, green, green/yellow and - in Austria - blue.

Ragnar_AT said:

I can tell you about Austria and Germany. ....

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Many thanks - that's all very interesting.

Ragnar_AT said:

The regs in both Austria and Germany are fairly relaxed on core colours for live conductors - basically any colour but yellow, green, green/yellow and - in Austria - blue.

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Presumably you mean 'live' in the sense of 'line' (i.e. nominally about 230V above earth potential), rather than the BS7671 view that both line and neutral are 'live' conductors?

I can understand those countries forbidding green and G/Y as live conductors, but what is yellow being 'reserved' for?

Even though the regulations in those countries are 'relaxed' about colours for live conductors, do I take it that there are established conventions which most people follow?

Kind Regards, John

Yellow on its own is prohibited, as is green, so I guess it is because together they signify cpc.

securespark said:

Yellow on its own is prohibited, as is green ...

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Indeed they appear to be - in Austria and Germany, and also in UK (along, in the UK, with all colours other than brown, black or grey

securespark said:

... so I guess it is because together they signify cpc.

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I suppose that is probably the reasoning. I have to say that, despite the BS7671 requirements as regards the proportions of each colour, small bits of G/Y can often look yellow at first glance!

Kind Regards, John