"Geoff Mills" wrote in message
...
On Wed, 16 Sep 2009 16:29:27 +0100, David Hansen
wrote:

On Wed, 16 Sep 2009 16:09:50 +0100 someone who may be Geoff Mills
wrote this:-

Is it common practice to return the cable down the same conduit that
it came up in,

Yes.

Assuming metal conduit, if there is not a copper protective
conductor drawn into the conduit then you need to be particularly
careful about making proper joints to maintain the continuity of the
trunking which forms the protective conductor.

Thanks,
I hadn't considered metal conduit before, nor that the conduit itself
could be used for earthing. Lots to learn.

Metal conduit is excellent if you need more mechanical protection than heavy
duty plastic offers, but it is not easy to work with. You need a pipe
threader and, if you want to make pretty shapes, which you can do with care
and a hot air gun in PVC, a pipe bender. As noted, the earthing it offers
can be unreliable, so I always run earth wires in it as well.

Colin Bignell