On Mon, 07 Feb 2005 19:16:34 +0000, Andy Lewis wrote:

I wish to lay an outside electrical cable to my garden shed 30 metres
from house, what is the best sort of cable? Cheap but safe and can I
bury the cable?
Thanks......

Armoured (SWA) is an option (there are others). I'm not qualified BTW -
but there are a few things that need to be considered. It's not
necessarily as simple as lob cable in ground and connect (it might be, but
not necessarily).

Cable needs to be routed suitably - including burying in correctly
prepared trench of certain minimum depth with warning tape above by a
specified amount (so far, still cheap, but much hard work involved).
Surround cable with sieved soil as stones can damage it. Cable can be
clipped to solid structures for some of its run - but not to a fence,
deemed too likely to fall over.

Also, there is a serious need to consider the earthing arrangements - I'm
studying this myself and am so far not totally clear - but it is *not*
necessarily the case that you export the supply earth from the house. It's
worth first finding out what type of earth the supply presents to your
house as this makes a difference to the design. You can end up in certain
cases with having to supply a local earth via rods and these should be
tested. That's going to cost but I can't stress enough that it's important
and is money well spent.

SWA is not particularly difficult to work with, but you need to have the
correct brass termination glands and know how to deal with the earths at
each end. It's best (to the best of my knowledge) to use 3 core for this
type of job, using one core as an earth rather than rely on the steel wire
armouring (which *must* also be earthed solidly or the cable is
potentially dangerous if you stick a fork through it).

I'm being cautious here as regulations applying to outside wiring are
quite onerous. I would recommend seeking an engineer's advice (or a
seasoned sparky) on the earthing requirements in particular,
which is what I am expecting to do myself.

Sorry to make it sound painful, but outside power really needs to be done
right.

HTH

Tim