Andrew Gabriel andrew@a17 wrote:
In article ,
Ian Stirling writes:
I have 3 2.5mm^2 T+E cables going to the garage, in a duct.
They are about 30m long.

Assuming 16 ohms per Km, that's .55 ohms.
Or around 40A, on voltage drop alone, so that's not a concern.

snip
My current plan is to common all the L/N/E, put a 13A fuse on each
live, and at the garage end, have a RCD CU, with a seperate earth spike.

Anything obvious that I've missed?

How do you protect against overload in the case of one or two
broken neutrals?

Oh dear.
True.

The obvious solution is to then fuse each neutral too, at both ends.
But this leads to unexpected behaviour in case of faults, as it can
still be live, though being 'dead'.

You possibly haven't considered a break in one live conductor
near the supply end which grounds only the longer leg, which
is backfed via both the other conductors fused at 13+13A.

Again true.
Oh well. Something to consider for the next rewire - I'm wanting to put
solar panels on the garage, so want lagged pipes in conduit, and I can
put the bigger cable in then.

For the moment, I think I'm paralleling them all, and sticking on a 16A
MCB - with the joins to the 2.5mm outside, where them going on fire
would at most destroy the buried conduit.

I don't need that much power at the moment - the main reason for putting
them all in initially was to reduce voltage drop - to be able to run a
3Kw kiln up there, and to hit it operating temperature spec, rather than
sort of wandering up there.

Thanks.