On May 15, 6:29*pm, Lobster wrote:
My house is not particularly well specc'ed for electrics; although we do
have fairly modern RCD-protected CU and reasonably new wiring, we don't
have adequate circuits and it's likely that one day I'll want to sort it
out and add a few ring mains when the opportunity permits (eg, when one
day that new kitchen comes to the top of the round tuit list...).

As others have said, it's unlikely you'll need a _few_ ring mains.

But if you do, and you're going to cram them all into a single conduit
for a decent run (couple of metres or more) then you need to de-rate
them. Which means using even larger cable.

So better to have a very large conduit, or several smaller bits of
conduit - not "just the right sized" single conduit with everything
crammed in. IMO!

Cheers,
David.