Adding sockets to an existing spur

[Splitz]

I want to add 2 double sockets to what is either an existing spur or the end of a radial circuit (there are only 3 wires) I cannot trace the cable back so I've no idea how it is wired at present. If I fit an FSU immediately after the existing socket will this then allow me to add the extra sockets? If I have a washing machine, spin dryer and deep fat fryer plugged into the new sockets will this cause a potential problem if they are all on at the same time, they are

 

[malcolmsanford]

My first plan would be size of those 3 cables, and the protection device for them. If they are 2.5mm say and the protection device is 32amps, then there is a great chance it is already a spur of a RFC, and as per appendix 15 you can only really have one single/double socket un-fused spur at each point of the ring.

If this is the case then you can be putting a serious load on that 2.5mm cable, even if your fusing your part down to 13amps, we all know that a 13 amp cartridge fuse will quite happily run for over an hour at 2 times it's rating, and then you got the whatever can be plugged into that first socket.

For me you need to know exactly what situation you have there, and you need to design your work accordingly, you can't really design something on a maybe. So if it is a unfused spur on a 2.5mm cable off a RFC, then no I would not advocate what you propose.

 

[brman]

So if you assume it is un-fused spur could you then replace the existing socket with an FCU, add a new socket beside it then extend to the additional sockets.
That way you just have one fused spur, albeit with a limit of 13A on the all the sockets.

It does all assume though that all the appliances are ok with a limit of 13A (ish) and that it is really is a single socket on a un-fused spur to start with.

Do you also need to consider RCD protection?

 

[malcolmsanford]

So if you assume it is un-fused spur could you then replace the existing socket with an FCU, add a new socket beside it then extend to the additional sockets.
That way you just have one fused spur, albeit with a limit of 13A on the all the sockets.Yes that is a way of doing it, but spurs in kitchens are really IMO not a good design. About the only place in a modern home you get any type of loading on sockets is in a kitchen, and so having 3/4 double sockets backed by a 13amp fuse is not what I consider a good design. 3/4 sockets on a fused spur in a living room or the like is more acceptable.

It does all assume though that all the appliances are ok with a limit of 13A (ish) and that it is really is a single socket on a un-fused spur to start with.

Do you also need to consider RCD protection? Almost certainly the additional work will need to have RCD protection. whether the OP decides to just RCD protect his work, or the whole circuit is agian his call. I would be trying to protect the whole circuit, could never see the point of have a socket RCD protected and 2 feet away one that wasn't.

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[brman]

Completely agree, particularly the good practice bit- I should have made that clearer!