"the yorkshire dalesman" wrote
| Is it permissible to have 13A sockets on 2 different ring,
| (or a ring and a radial) circuits serving the same area
| of the house?

I think it is a rather sensible idea actually; it means that if one ring is
down you have somewhere close by to plug in the inspection lamp / hot air
gun / radio / teasmade / whatever.

The two caveats a

1. Phase separation - unlikely to arise in a domestic dwelling which are
normally not supplied 3-phase.

2. Clear labelling of circuits at the CU ot prevent confusion.

| What prompts this post is that IIRC it
| is standard advice that all downstairs 13A sockets should
| be on an RCD circuit.

That is because there is the possibility they may be used for outdoor
equipment. Sockets which 'may' be used to power outdoor stuff MUST be RCD
protected.

| What I should like is to put sockets for electronics (computers, TVs,
| clock radios etc) on separate circuit(s) to those used for kit which
| is likely to trip RCDs. There would be 1 or 2 double 13A sockets on
| this ring or radial in most rooms. I get a fair amount of tripping
| from portable outdoor kit like hedgecutters - portable workshop tools
| (sanders, planers etc) are another bane. So the 'electronic' sockets
| would be run through a normal switch & cartridge fuse or MCB &
| definitely nowhere near an RCD.

Whether or not you require RCD on sockets will depend on your installation
and its earth arrangements. If you require RCD protection to comply with the
disconnection time of 0.4s on a socket, you cannot omit that simply because
you want to plug your clock radio in.

The best thing to do would be to install dedicated circuits for your outdoor
and workshop sockets which do not run through the same RCD as your house
sockets but have their own RCD protection.

If you have a split load CU, you could take a supply using a spare circuit
on the non-RCD side to individual RCD-protected sockets or a new RCD for
that circuit only.

If you have a whole-house RCD, this should really be replaced as it is
unsafe (a fault in your workshop could leave you without lights and with a
power tool spinning down).

Owain