Geoff's post reminded me of an incident some years ago just up the road from me, a builder mate rang me, 'can you get over here quick, the plasterer has sparks coming off the ceiling' he told me, sounding very excited. I jumped in my van and went round to the house, the plasterer had started to skim a ceiling, it was a typical bodge job, leave the light fitting up and skim aorund it, you've all seen them.
Well it was all going well until he came to the plaster around the fitting, a large brass three arm thing, he'd felt a couple of tingles as he'd been putting the plaster on the ceiling but ignored it, then he'd seen a couple of flashes. I tested from a neutral at a socket to the metal of the fitting, 240v! It would even light a test lamp with a 15W lamp in it.
I turned off the power and removed the fitting, there was no earth on the main cables, they were the old twin type, so we had live in, live out, connected with the ubiquitous terminal block, neutral in and out, connected in the same manner, we then had the switch wire, red into the live in and out, and black to the fitting (no sleeving).on the fitting we had a brown, a blue and a green/yellow, the blue went to the neutral, the brown to the switch wire (single black) and the earth went to the 3 reds (loop live)!
At this point the customer walks in and asks what all the fuss is about, 'that fitting has been in for years mate, fitted it myself and we've never had a shock off it, in fact the wife wipes it with a damp cloth every weekend' . The reason he'd stuck the earth in with the lives was because he 'knew it had to go somewhere and that was the only spare wires he could connnect it to' ,it's amazing that a good carpet (foam backed) and a pair of wooden steps can give such a good level of insulation, otherwise he could have ended up with a dead wife!
Believe it or not I had an identical fault a couple of weeks later, a freind of my wife's was moving home and wanted all her fancy lights taking down and replacing with pendants so she cold take them with her to the new house, ' you shouldn't have any problems, I fitted them myself so they were done properly' she proudly informed me. The first fitting I removed was a large brass chandelier in the lounge, again the supply cables were the old twins with no earth, and once again the earth had been connected to the loop live.
