On Mon, 05 Apr 2004 00:22:16 +0100 (BST), in uk.d-i-y "Dave Liquorice"
strung together this:

On Mon, 29 Mar 2004 17:47:38 GMT, Lurch wrote:

No. If you fire the genny up and plug something in is it unsafe?

Depends...

It's the same as powering a few small items in the house throught
the existing wiring.

Except that without N bonded to E and L E fault will not cause any
fault current to flow (think about it there is no circuit...) but will
raise the N way above E, probably up to the full generator output
voltage. Bear in mind that most switches and MCBs are single pole in L
then things "switched off" aren't.

That would also apply to anything plugged directly into the genny.
It'd be no more 'unsafe' than just plugging something in to an
extension lead on the genny.

Also as N and E are quite likely to
be interconnected somewhere the installations E could also rise to the
full generator output voltage.

Where would they be connected?

One end of the generators winding needs to be bonded to the frame of
the generator and to local earth and to the main earth terminal of the
installation. It is the bonding of local earth to the main earth
terminal and thus the suppliers earth that can be problematical with
some types of installation.

That is why when using a gennerator you should isolate the suppliers
earthing facility with a link, or just unscrew it, and turn opff the
main switch of the CU or use a changeover switch.

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.

Assuming that the gennys earth terminal also bonds to one of the
generators phases.

I seem to think that most are.
--

SJW
A.C.S. Ltd.