ARWadsworth wrote:

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...).

Anyway, shortly due to arrive at the top of said list is the
redecorating of the hall/stairs/landing (urgh). Now, the CU lives in
a low cupboard in the hall, and all the cables running from it are
buried in the brick/plaster wall above it, travelling up to the ceiling.
Can't see any scope for adding in any new cables without serious wall
surgery.
So it occurs me that *now* would be a good time to bury some form of
conduit in the wall, separate but adjacent to the existing cables, to
enable me to run new cables at some time in the future. It would
clearly need to be a pretty large cavity to be worthwhile (I might
want to put several ring mains down there, and they'd have to be pulled
through which would be awkward). "Large" to me implies fairly deeply
buried, to ensure the overlying plaster is rigid enough not to crack.

While I'm mulling this over in my head, I'm just wondering if anyone's
tried something similar and have any tips for suitable conduit,
methods etc?

Well I know that Tim Watts installed his house electrics in conduit, I'm
sure he'll be along soon with some of his tips.

I doubt you need to be more than 3 to 4 mm from the surface to prevent
cracking.


Bing! and the shopkeeper appeared, as if by magic ;-

IME I found 20mm oval was OK upto 2.5mm (with slop) and fits into the holes
in backboxes.

Not reason the OP can't go to a larger width oval here though which would
make larger cables possible and generally easier to thread. I can push off-
the-reel 2.5 down 20mm oval from one end over a 2m drop - but for longer
lenghths, bigger oval would be wise or it may get hard going.

I've got a couple of bits with 2mm plaster over a couple of places, but
that's cutting it fine (lots of PVA and plaster squeezed around and behind
the conduit - I'd try and get 4mm over, but that's still not a very deep
chase and is quite likely to fit in the depth of plaster available.

--
Tim Watts