Is it OK to wire a spur consisting of a radial (2.5mm T & E cable) to two adjacent SFU's for a 10amp supply on one of the SFU's and a 2amp supply on the other SFU.
Spur SFU's off a ring main socket
- Thread starter wildman147
- Start date
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Not really, IMO, since there's no guarantee that someone won't come along in the future and put 13A fuses in both SFCUs and connect both to high loads - it would therefore be advisable for each SFCU to have its own separate 2.5mm² feed from the ring. Others may disagree, on the (true) basis that the present situation (with 10A and 2A fuses) would not be a problem.
Kind Regards, John
If you use just one FCU (13A) and used 1.0mm² cable to both items you wouldn't need a 2A fuse.
Very true, but the MIs of whatever is on the end of the '2A supply' might be demanding something smaller than a 13A fuse.
Kind Regards, John
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Yes, might do but the circuit will comply whatever else is put on it.
What do you think would require (by the manufacturer) a 10A and 2A fuse?
I was imagining a 2A socket being fitted and a misunderstanding of the meaning.
What do you think would require (by the manufacturer) a 10A and 2A fuse?
I was imagining a 2A socket being fitted and a misunderstanding of the meaning.
Unless I'm reading it wrong, the plan is to have one FCU supplying two further FCU's in a radial.
I see nothing wrong with this as it's entirely no different (in fact, less of a problem) than FCU - 2 gang socket - 2 gang socket
The arrangement is still protected by a 13a fuse in the first FCU, not like you can put a bigger fuse in, even if you did connect 2 x 3kW heaters to the two FCU's, you're just going to blow the supply fuse in the first FCU (after a bit of overheating of course)
I see nothing wrong with this as it's entirely no different (in fact, less of a problem) than FCU - 2 gang socket - 2 gang socket
The arrangement is still protected by a 13a fuse in the first FCU, not like you can put a bigger fuse in, even if you did connect 2 x 3kW heaters to the two FCU's, you're just going to blow the supply fuse in the first FCU (after a bit of overheating of course)
Agreed.
Possibly - hopefully the OP will clarify. I was thinking that maybe there was one load who's MIs were calling for a 2A or 3A fuse and that the OP, thinking that the whole spur should be limited to 13A max, therefore decided on 10A for the other FCU. Hopefully we'll get some more information.
Kind Regards, John
If that's what was meant, it would obvioulsy be fine - but that's not how I read it (I assumed he meant just two FCUs fed from the same connection to the ring). As I've just written, we need some clarification.
Kind Regards, John
I agree with John as far as the number of FCUs proposed.
I was merely pointing out that if both spurs are wired from the load side of the one FCU then, electrically if the correct cable is used, no further fusing is required.
If you extending the radial circuit from a socket outlet to a FCU, I suggest the same CSA of cable is used as the existing radial circuit, then the circuit can be down fused and a reduced cable sized used, if wanted.
Depending on the location of the accessories it would be possible to extend the circuit in away that would only require two fused connection, to be installed, one for each 10A & 2A loads.
You should not spur two cables from the same socket outlet.
Ah 'ring' in heading and 'radial' (missed) in post.
That doesn't alter my interpretation (perhaps wrong!) of what the OP wrote. I thought, and still think, that 'radial' was used to describe a single cable spurred from the ring and feeding the supply side of two FCUs. Only the OP can clarify.
Kind Regards, John
HI John you are right in your assumption of a spur off the ring to two FCU's As I thought that it was ok to spur a double socket off the ring it would be ok to spur two FCU's as both senarios are capable of supplying two 13amp loads in total (although I am only supplying a total load of 12 amps) I would appreciate your thoughts on this. (wildman147)
if that is the plan, then it's not acceptable.
You can take each FCU from a different point on the ring, or use one FCU to feed the other two, but two from the same point on the ring is not allowed
You can take each FCU from a different point on the ring, or use one FCU to feed the other two, but two from the same point on the ring is not allowed
Ah, my thoughts
The regulations are not necessarily very logical/consistent about this since, although (as you say) they allow a double socket on an unfused spur, they do not allow two single sockets (or, indeed, two 'of anything' - which includes your situation). Don't ask me to explain/justify that, beyond the fact that, contrary to common beliefs, double sockets are not designed to be able to cope with 2 x 13A loads - 20A (not 26A) is usually regarded as the maximum, with the instructions of some seemingly implying that the acceptable total is only 13A (across both socket outlets).As for your situation, it would be helpful if we knew what loads are going to be attached to your two FCUs. As has already been suggested, one option that might be possible would be just to have one FCU, with a 13A fuse, supplying both loads (with suitable cables to the loads, both capable of carrying 13A). Alternatively, if the smaller load must have a 2A or 3A fuse, you could take the spur cable to an FCU with a 13A fuse and use the load side of that to supply both your larger load and the 'supply side' of a second FCU with a 2A or 3A fuse. Other ideas might be forthcoming when we understand precisely what you need to achieve.
Kind Regards, John
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