What would have happened-Electrical question?

I did the wiring on a newbuild a few months ago, and today the electric meter was fitted. The job was all ready to finish as my CU tails were waiting in the meter cupboard to connect to the isolator that the eletricity co have supplied.

Whilst I was fitting the tails my apprentice pointed out that there was a kettle plugged into a socket in one of the bedrooms and when he turned it on it worked. I went to look and so it did. A look around the house found an extension lead from a neighbours house passing (trapped as the door was shut) under the UPVC back door and then from the extension was a lead made up of two plugs at each end.

This "lead" had one end plugged into the the extension lead from next door and the other end into a socket in the house and to make matters worse it switched the live and neutral so the house sockets had reversed polarity

What would have happened if I had powered up? I have not yet checked to see it the two houses are on the same phase.

Adam

PS It was the decorator that did the extension lead bodge, a friend told him how to do it and therefore have the sockets powered up for a light, radio, kettle etc

Reply to
ARWadsworth
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As there was a polarity swap there wold have been two faults both phase to neutral. So the 13A plug fuses at both ends would have blown and/or the MCBs on the relevant ring circuits in each house.

Without the polarity swap there would have been a phase-phase fault which (unless the phase was the same - v. unlikely) would have again blown one or more or the 13A fuses or tripped MCBs.

Reply to
Ed Sirett

YOU did the wirining on a new build and employing an apprentice, so presumably you are a qualified sparky, and you are asking this question? Should you not know the answer or am I missing something?

Cheers

John

Reply to
John

This crossed my mind but I did not want to be the first to mention it, as i normally get flamed.

Steve Dawson

Reply to
Stephen Dawson

Something would have tripped thats all.

Reply to
The Natural Philosopher

I recon it would have just blown the 13 amp fuses. I did not fancy finding out

Adam

Reply to
ARWadsworth

Even with a full short circuit there's a good chance (IME) that the MCB would have tripped either as well as or instead of the plug fuse.

Reply to
Ed Sirett

Bugger all - simple overcurrent fault and the MCBs / fuses should go. In this case (same phase, phase and neutral reversed) the live will break in each house.

If you do it between phases, then exactly the same thing happens.

If you do it between phases and the conductors weren't reversed, then you would see a current flow owing to the phases difference, and again an MCB (just one this time) would pop.

It's basically equivalent to sticking a short circuit across the circuit. Big fault current, but things are designed to cope with this and that's why we have MCBs.

The real dangerous hazard here is the plug with bared live pins, if it's unplugged at one end.

I'd second the recommendation re where the painter should store this cable...

Reply to
Andy Dingley

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