DIY Doctor

Sparking drill?

Postby andy2510 » Sun Jun 10, 2007 10:14 pm


While I was drilling holes for a shelf unit I encountered sparking from one of the holes. Later when I was re-drilling the same hole with a slightly bigger drill piece I got an electric shock from the drill.

The wall in question is an upstairs brick party-wall between two houses, so stud detectors will be no use, and there isn't a plug or light socket on this wall in this particular wall, though there are 2 other switches further along this wall in the toilet and on the landing (which are both lower than the shelving unit and whose wires come from directly below and go diretly above to the fittings). The room above is an unconverted loft whose power seems to come from a plug socket and is wired externally (though I've not been able to fully check up there).

I've just recently moved into this property and so am unable to fully know the location of all wires. I'll try and contact the previous owner on that point as the place was rewired when he was owner.

I'm a bit paranoid (and worried sick!) that I've hit a power cable. I thought I felt a minor shock by touching the wall, but using a voltmeter against the wall shows no trace of escaping power. Also the socket circuit didn't cut out when the drill sent out a shock.

Is there any other way for drill to shock/spark like this? Any help will be appreciated.

Sorry for the long post.
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Postby neilh » Mon Jun 11, 2007 11:42 am

If you got sparking from the drill bit, then strongly suspect you have
managed to drill into a live cable.
To be really sure, you are going to have to carefully clear away the plaster to see what you may have touched.
One word of warning:- do NOT rely on one of those neon indicator screwdrivers to see if a cable is live. Use a testmeter.
Only way to see where it is fed from would be to measure with meter, then switch off individual breakers @ the consumer unit.
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Postby andy2510 » Sat Mar 22, 2008 11:02 pm

Sorry to dig out an old topic!

It was a really rubbish drill! It came with a cheap toolbox set I asked for at Christmas. Just 'revving' it up now and I can smell burning! I've since been given a much more powerful drill so I won't fall into that trap again!

The wall is a party wall with no cables running through it whatsoever.
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Postby chris_on_tour2002 » Thu Apr 03, 2008 3:03 pm

just one extra point, it is perfectly possible for a drill bit to spark when attacking masonry. bricks and blocks come from all different quarries and sources and are made up of all different minerals (flint for example) and can spark when coming into contact with metal and friction is applied. one possibility as to why you saw sparks. always best to assume the worst thogh!
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