John Rumm wrote:
Toby wrote:
Hi,

I am going to be running SWA cable out to the garage soon (Total run
is a little under 20em from the house CU to the garage CU)

I will also be installing a generator point on the garage, which will
be connecting to a proper transfer switch in the house.

It will be easier and cheaper if I just run a single SWA cable with 4
cores, two for the generator and two for the feed into the garage.

Is this permitted, or do I have to have two separate cables?

The SWA will be terminated in the house and garage in a metal box,
then the two circuits taken from there to there respective places.

The main complexity sounds like it is going to be dealing with earthing
and possibly main equipotential bonding. What earthing scheme do you
have in the house?


The idea was to use the SWA armour as the earth for both and have an
additional earthing rod next to the generator point connected via 10mm
cable (Generator is only 7.5KVA).

The generator transfer switch This one -
http://www.briggsandstrattongenerato...ertransfer.htm
does not have the facility to switch the earthing, so I am assuming all
the earth connections can stay connected all the time?

My main earth is supplied by the armour of the incoming supply cable (TN-S)

Is there any reason the earth connection to this can't be left connected
in the event of a power failure with the generator running?
(I assumed it is OK as the transfer switch does not have the facility to
switch the earth connection)
The generator has one leg of it's output tied to ground, so there will
be no potential difference between neutral and earth in the system. If
live found it's way to earth, this would just create a short, tripping
the MCB, so, as far as I can see it, there is no risk to anyone working
on the power grid here (just like the power company ties their neutral
to earth everywhere)

Also any reason the earth rod can't stay "in circuit" during normal
operation (considering the lead water pipe is connected to the earthing
system 24/7 via 10mm cable and this will be acting the same, if not better)

In reality the generator won't be running very often, as the mains power
supply should be reliable, but I already have the generator, so am just
making provision for it's use "just in case" - If I move out, it will be
coming with me too, so nothing to worry about later on either, it will
simply be disconnected.

Toby...