Apologies, that it what I meant.
Ah but is it actually forbidden by regs or simply not listed as suitable?
Straight con surely implies that the 'outer conductor' is a PEN, which is specifically forbidden within installations by 543.4.1 of BS7671 (with the very rare exceptions mentioned in 543.4.1) - and, in addition to that prohibition in BS7671, the Note to 543.4.1 points out that..
Doesn't need to be a PEN if you run a separate CPC. But if you are going to do that, why use straight con ...
It is. Up to and including the service head (main fuse) belongs to the DNO. From there to the meter belongs to the meter operator (may be your supplier, or may be a separate company under contract). The outgoing tails from the meter and everything downstream belongs to the customer.
For a start, as you say, what would be the point? However, talking of 'points', is it not more to the point that the neutral would then certainly not be 'insulated and sheathed' - some might call it 'single insulated', but it would probably be more accurately described as 'non-insulated but sheathed' - which surely would not be BS7671-compliant?
Same point - the neutral would be protected by only one layer of insulating material (however you wish to describe that), hence presumably not compliant - any more than would be using a single-insulated single for the neutral.
Sometimes things are used because there's a load lying around for whatever reason. Apart from that, I can't see one.
I believe you are correct. I see that split con has insulated neutrals, I hadn't looked it up to see that straight con has non-insulated neutrals. Not having had any reason to use it, never looked at it in detail before - learned something new today
Agreed - but it's hard to see why anyone who did work within electrical installations (rather than a DNO worker) would have any reason to have any straight con 'lying around'. In any event, as I went on to say, I can't see that straight con would be compliant within an installation (i.e. per BS7671) for L+N (and even then one would need a separate CPC). I suppose a pair of straight con cables could be used (one for L, the other for N, each with the outer being a CPC) - but that would seemingly be plain silly!
Indeed. If I recall correctly (and if they're still there!), I think that this forum's wiki has some nice pics of both straight and split con.I believe you are correct. I see that split con has insulated neutrals, I hadn't looked it up to see that straight con has non-insulated neutrals. Not having had any reason to use it, never looked at it in detail before - learned something new today
And yet there is a distinct symmetry in the installation which strongly suggests both the incoming and outgoing sides were installed by the same person, not a piecemeal process of a DNO installing a service head, a supplier installing a meter and a customer's electrician installing wiring on to the rest of their installation.
That had struck me as well - it's not the sort of thing you would expect to see if they weren't done by the same person (or at least, people trained to work in the same way).
Is it me, or does it look like the neutral for one phase of the right hand head comes from the left hand service ? it looks a lot like 2off 3 phase supplies going off to 6off single phase meters. Also, there's only one earth which comes off the right hand head.
I hadn't noticed that, either.
All true, and I did think of that - but it still wouldn't surprise me if 'as a matter of principle', they (**) didn't want earth fault currents going through any part of the meter.
Only if, as you have postulated, a PEN is going through the meter. With the 'usual arrangement' the earth fault path bypasses the meter by virtue of the installation's earthing conductor being derived from the PEN upstream of the meter.
That's certainly true in relation to my (albeit limited) experience of 'standard supply arrangements'.I think the only thing we can be certain of is that it isn't a standard supply arrangement
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