Good evening guys,
Went to a house during the week to fit a shower circuit and put a light into the loft at the same time. As I entered the loft I was confronted by the attached photo's. now, first off, I know the 'volt-sticks' are not reliable dead testers, however, they are handy for quick checks of cables for anything nasty that needs testing further and I always have one in my pocket. At first glance, I thought to ask the client when I saw her next if she just wanted me to cut it down and get rid. At second glance I got out the volt stick out of habit and held it up to the exposed and corroded copper showing through the perished rubber.
I nearly fell through the ceiling when the volt stick lit up like a christmas tree and beeped it's tone at me!!!
What isn't shown on the photo's is that the cable runs through a partition into next doors loft. I have to admit that the porcelain insulator got me worried, though the small size if the the crumbling cable connected to it confused me (looks like 2.5mm).
I went down and switched off at the mains to see if anything was still on it only to find that it showed dead with the volt stick. OK, go get the long lead and megger MFT out, test, still dead. Turn the power back on and the upstairs lighting and sockets only, MFT shows near enough 100v and the volt stick goes mad again. Isolate socket cct and same thing.
Upstairs lighting cct has no earthing ( CU is labelled correctly), and I then thought to check the 1.5mm I had laid into the loft for the lighting cct and clipped most of the way, with the volt stick and even though it was connected at neither end, got a result.
Is this a common thing? I can only assume that with a lack of earth to absorb any induced voltage that the whole lighting circuit is inducing a standing voltage into anything it comes accross?
