I knocked down an old shed from the previous house owner, which housed as small consumer unit connected to sockets and lights. Protected cable is partially buried in the ground and connected to a 32 amp breaker in the consumer unit in the house. Can I replace the old outdoor electrics with a single 16amp double socket? So in short, if the cable is big enough for the breaker, can I run a radial circuit with single double socket or do I need a smaller MCP? I don't want to replace the old cable. Many thanks!
Replacing a small consumer unit with a double socket in outbuilding
- Thread starter JoMike
- Start date
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Doesn't sound right, unless you have a decent sized cable. So some questions, I'm afraid...
What sort of cable is it?
What size - that means the csa of the conductors.
What sort of cable is it?
What size - that means the csa of the conductors.
Umm, no such thing as a 16amp socket, at least, not in domestic use..
You mean its a 3core cable with an approx 10mm overall diameter?
You can find specification tables on manufacturer websites https://www.doncastercables.com/cab...ded-and-Sheathed--Steel-Wire-Armoured-Cables/ But even 1.5mm² 3core is shown as being 11.9mm in diameter. So if you want to size it that way you'd have to swap the tape for a pair of verniers
Have a look to see if the size is embosed on the side, or look at the cores (if you are able to visually guage them)
You can find specification tables on manufacturer websites https://www.doncastercables.com/cab...ded-and-Sheathed--Steel-Wire-Armoured-Cables/ But even 1.5mm² 3core is shown as being 11.9mm in diameter. So if you want to size it that way you'd have to swap the tape for a pair of verniers
Have a look to see if the size is embosed on the side, or look at the cores (if you are able to visually guage them)
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He clearly does.
In fact, the first one I looked at says 12.17mm. Given that SWA less that 1.5mm² seems rare (does it exist at all?) I would guess that the cable (assuming that it IS SWA) must be 1.5mm² (and certainly no bigger) - and, if so, the house breaker protecting it would have to be reduced to less than 32A.
Indeed, even if it's not SWA, I doubt it is any bigger than 2.5mm², so the 32A breaker would still be too high a rating.
Yes, electrically-speaking it would be no different from feeding just one double socket (i.e. max of 2 x 13A downstream fuse) with a 2.5 mm² unfused spur from a 32A ring final (or a 2.5 mm² unfused branch from a 32a radial).
However, although I'm not sure that they would/could 'code' it, I suspect that the eyebrows of an EICR inspector would probably rise if they came across a "2.5 mm² radial circuit" protected by a 32A MCB, even if it was currently only supplying one double socket - presumably on the basis that it was far from impossible that the circuit would get 'extended' (by additional of further sockets/whatever) in the future.
As always, one can debate to extent to which one needs to anticipate ('non-compliant') things which "might happen in the future" - but the situation we are considering could at least produce some 'hassle'!
Spurs may originate at the source of the circuit (the MCB) but with no ring and only a spur it's a grey area and there's not really a reason to keep the B32.
Anyone who extends a 2.5 mm2 radial protected by a B32 clearly isn't competent though, so I'm not sure we need to take that possibility into consideration.
Anyone who extends a 2.5 mm2 radial protected by a B32 clearly isn't competent though, so I'm not sure we need to take that possibility into consideration.
Yes. The future is totally irrelevant.
It probably shouldn't be but, as I said, it could be regarded as a 'grey area' (or worse!) by an EICR inspector!
As I implied, I agree that 'what may happen in the future' should be irrelevant - but, as I've said, that does not guarantee that, say, an EICR inspector will not make a fuss about it - and I tend to favour 'a quiet life'
In any event, considering just the 'now', I see no reason why the MCB should not be reduced to 25A (if available), or even 20A - and, even if it's 1.5 mm² cable, that would (certainly with a 20A MCB, even a 25A one with 2.5 mm² cable) 'keep everyone happy and fuss-free'
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