Bill wrote:

Hi all,
Some time ago I picked up a 7.5KVA generator complete with auto
start control panel. I feel it is about time I wired it up to the house.
I rewired the house, 4 bed plus annexe, some years ago and feel
relatively confident in being able to interface it to the CU. Talking of
the CU I'm contemplating putting in a second one so that I can have
maintained and none maintained circuits. All of the lighting but only
some of the power. This should ease the load on the contactor that
switches between the boards feed and the genny.

With 7.5kVa this might not be necessary

My questions a-

Am I OK in using a two pole change over contactor, common to
house, n.c. to board and n.o. to genny?

yep

Any ideas on a reasonably priced contactor and what sort of
current rating?

7.5kVa @: 240v = 31A, I'd go with 40A


I've seen a few advertised and obviously the higher the
current the higher the price! As it will not be providing a circuit for
the electric shower would I be OK with something around 40A rating,
bearing in mind the second CU?

What should I do about the earth? TN-S at the moment. Will it be
necessary to switch this, I suppose with a multiple number of faults it
could be remotely possible to back feed this to the boards earth. I
don't really fancy switching it if I don't have to though. Would I be OK
just connecting one side of the genny output to N and earth? Should I
then provide a local earth?

you will need a local earth


Should I just go out and buy a box of candles instead?

If youre not sure, then yes. The only point to doing al this is if
theres a good reason to do it. And there usually isnt. If you can think
of nothing better to do, I suggest a life re-evaluation time.


NT