One of the double sockets in our garage needed replacing (damaged after a washing pole hit it) – a pretty trivial job that I'd done before. So I flipped the MCB for the ring main, used a non-contact voltage tester to check nothing was there, and set to work. I disconnected the old socket fine, and was lining the cables up to fit into the new socket when… ow.
My finger bridged the live and earth pins, and suffice to say the live wire was very much alive. Bar a few finger spasms I was fine fortunately, and believe me I realise I was very lucky in that respect (I'm in the UK, so that was 240V.) Before finishing the job I then shut off the entire property's electrics – I was taking no more chances.
Further inspection confirmed two things I immediately suspected at this point – the MCB in the garage (installed before we moved into the house) was shutting off power via the neutral, not the live, and the voltage tester was dodgy (I had tested it on the same socket earlier and it seemed fine, further testing showed it presumably had a loose connection internally and only worked sporadically.) Needless to say it's now in the bin, and an electrician has been called to sort the MCB and check the rest of the house for similar issues.
Unsurprisingly this has shaken me up a bit – I would say I'm a rather safety conscious person, and in this case thought I'd done all the checks properly (including taping over the relevant trip switch to ensure no-one flipped it back on while I was working.) In some ways I can't help feeling I was unlucky that the MCB was wired by a cowboy, in combination with the voltage tester failing in the way that it did, at the time that it did. However, I'm not one to solely blame tools – clearly some, if not most of the blame here lies with myself also.
So in short, what should I have done differently – and was I primarily being stupid, or really quite unlucky?
Best Answer
The paranoid way to use a non contact voltage tester is:
The last step is what would have saved you a shock here - its to check that your tester didn't die while you were flipping the breaker, and that you haven't done anything silly like forgetting to turn it on.
Though if it were a loose connection you still could be very unlucky and have it pass all those tests with the outlet still live.