On Mon, 29 Mar 2004 17:28:22 +0000 (UTC), in uk.d-i-y " Tim \(Remove
NOSPAM." strung together this:

Ok guys,

Our national grid system appears to be a TT one- where the earth conductor
is connected back to the neutral wire at the service fuse where it enters
the house,

That's not TT.

*and* there is an earth rod too, connected to same.

That is. I think what someones done is provided a backup TT earth in
addition to the TN-C-S earth supplied by the electric company, just in
case it's lost at their end.

I am wanting to install a generator change over unit, which will isolate N
and L from the grid and allow the gen to feed the house. (Honda 6kva)

Question:

Do I need to earth stake the genny from its earth terminal, and / or connect
the generator plug's N and E together to bring the N line of the generator
down to zero potential to create a safe system???

No. If you fire the genny up and plug something in is it unsafe? It's
the same as powering a few small items in the house throught he
existing wiring. For extra safety you could install an earth spike and
connect it to the generators earth terminal, that's about all you'll
need to do.
--

SJW
A.C.S. Ltd.