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Electrical assistance required

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Jonnyboy

Joined: 29 Oct 2004
Posts: 23956
Location: under some rain.

Posted: Sun Sep 25, 05 8:32 am Post subject: Electrical assistance required

Ok, I've done something a little bit naughty with my wiring and need to check that it's not overly dangerous.

At present our house is 99% finished, second fix wiring is all complete. Due to series of cock ups our supply won't be connected until the 7th october.

So, to keep us going and to enable me to work at night I've done the following.

Just before the main circuit board, after the meter, I have disconnected the supply wiring Live and neutral and replaced it with a heavy duty cable that runs outside. This terminates on a plug and additional RCD which is in turn connected to my generator.

The earth on the wire is connected to the earth on the main circuit board, I have left the supply side earth in place as the earth spike is already connected.

I've connected a total of 10, 9w LV bulbs and only switched on the llighting breakers. Everything seems to work OK and the lights are working fine. I don't intend to use sockets but I will also be powering the central heating pump and the septic tank pump which are about 40w each. The generator will supply around 3kw, and I've had it running power tools whilst feeding the house as well with no problems.

So, have I done anything that is dangerous or potentially damaging?

jema
Downsizer Moderator

Joined: 28 Oct 2004
Posts: 28235
Location: escaped from Swindon

Posted: Sun Sep 25, 05 8:39 am Post subject:
I don't see a problem myself. But i am an amatuer at electrics.

dougal

Joined: 15 Jan 2005
Posts: 7184
Location: South Kent

Posted: Sun Sep 25, 05 10:07 am Post subject:

What you have done is probably officially 'naughty'.

BUT if the house wiring has been fully checked and signed off, then it ought to be safe.
It might be worth checking that the "plumbers wiring" has been checked and is certified ready to use before running it.
Were you planning on having a sparky in attendance for the grand (mains) switch on?
All your earth's are tied together and use the earth spike that is going to be used in the permanent config.
I'm not completely sure about the RCD at the genny, if the earth is 'downstream' of the rcd - it may depend on the rcd as to whether it would work like that - I dunno, but simply flag it up as strange, unusual and unknown to me. Worst case is that that RCD gives you no protection...
Depends on the genny as to whether it'll give a smooth enough output for electronics, but you've already shown it works with motors and fluorescents...

Trust the tails from the meter are secure and safe.
The problem comes if those go live before you expect... care, etc on reconnection!

Jonnyboy

Joined: 29 Oct 2004
Posts: 23956
Location: under some rain.

Posted: Sun Sep 25, 05 4:36 pm Post subject:
I it won't go live until I say so, I've got a 50m duct to dig first! I'm not sure if the generator rcd is useless either. I'm going through the rcd and breakers on the fuse box anyway. Yes it is officially naughty but I've been told it's fairly common site practice!

alison
Downsizer Moderator

Joined: 29 Oct 2004
Posts: 12918
Location: North Devon

Posted: Sun Sep 25, 05 8:24 pm Post subject:
Ade says you should have no problem. Is the earth a spike or pole mounted. If it is definately a spike you should be fine.

nathanbriggs

Joined: 23 Mar 2005
Posts: 35
Location: Chester

Posted: Tue Oct 04, 05 11:05 am Post subject:

The RCD is giving you NO protection unless the generator neutral is connected to earth at the generator (upstream of the RCD). However this may be LESS safe than leaving the two wire generator unearthed.

On small generators the output windings are typically left "floating" no connection to earth, this means you have to touch both wires to get a shock hence RCD is no help. On larger/pricier systems you have the ability to tie one leg to earth and make it a "neutral" which if you subsequently fit an RCD will give you protection. But then only touching one wire will give you a shock.

As long as you are not open to the public you are not breaking the law on public liability and as long as you don't try and parallel your generator to the mains you are not breaking ESQCR regs.

Your house wiring can't be certified while you are in this state but I imagine this doesn't bother you.

Your main problem is that you have little or no protection against electric shock if you have an accident, the generator is not "man enough" to blow your fuses, it will just keep on pumping electricity into you until someone switches it off. This is why building sites and the like have 55-0-55V tools run off isolation transformers, building sites are dangerous!

Good luck

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