Another wiring question... 20A or 32A fuse for this mains cirquit?

[Jake]

My small bungalow has a ring main wired with 2.5mm cable. But it is not 100% wired as a ring circuit; not all of the sockets have two cables connected. Some are conected to a single 2.5mm cable going to a junction box on the ring (i.e., they are spurs). Does this mean the circuit should have a fuse of no more than 20 amps?

If so, is there any point in it being a ring circuit at all? Could the person who wired it up have saved several yards of 2.5mm cable and just made the whole circuit as several spurs coming from a 2.5mm feed with a 20amp fuse?

In the kitchen, there are two double sockets above the worktop. These are fed by just one 2.5mm spur. Is this OK considering that a nicrowave, a kettle and a toaster might be fed simultaneously from these sockets?

Thank you,

Jake

[dom]

AIUI spurs should be single sockets.

[Jake]

I wasn't aware of that. Can anyone confirm?

Jake

[Jake]

I'm curious about this, as I recently spoke to a Patrt-P qualified electrician to get a quote for having another pair of double sockets added in the kitchen, and he was talking about routing the cable along the wall, behind the cabinets in mini-trunking. If each double socket needs two cables, that would mean four cables in total... more than would fit in mini-trunking, I think.

Jake

[EricP]

No, it's one double socket, not a single.

[Owain]

No, provided the regulations concerning unfused spurs have been complied with.

No, because (a) trhe flor area may be larger than recommended for a 20A radial; (b) the anticipated demand may be greater than 20A; (c) rings are often more efficient in cable use anyway.

No. An unfused spur should feed *one* single socket, double socket, or FCU. Two single sockets was formerly permitted (and can cause confusion because the 'middle' socket will have 2 cables and can be mistaken for being part of the ring).

If it's a fused spur, more than 1 socket is OK but total load will be limited to 13A.

A microwave, kettle and toaster aren't too bad as they are usually in use for only a few minutes at a time. Washing machiens and tumble dryers are worse as they are more sustained loads.

Owain

[Dave Plowman (News)]

Or a double. But not two singles.

[John Rumm]

No, a spur can be one single or one double socket (or a FCU etc).

[John Rumm]

No. The 32A MCB will still provides fault (i.e. short circuit) protection for the spurs. The fusing on the socket end of the spur (and the physical limitation of only being able to connect a notional 20A of load provides protection from overload on the spur cable.

Yes, very much so.

You could make the circuit a radial with a 20A MCB, but that results in a significant reduction in overall capacity - especially in a kitchen which typically has a high concentration of high current devices.

No, this is not ok. If more than one double socket is fed from a spur like this, then the spur must be a fused spur. This will have the effect of reducing the total capacity for all the sockets on the spur to 13A combined total. For a kitchen this is not really a satisfactory solution. So either the second socket should be moved to its own spur, or better still an extra cable added to join the sockets into the ring.

[Jake]

Thanks, John. I have decided to do the latter (add the extra cable).

Jake