Hi guys. Sorry for the delay. Busy, busy, busy.
Thank you for your suggestions/questions/grumbles ;-)
To answer (in order):
Static zap - The cpc is continuous to fittings.
But there are two unaccessible wall lights behind an artificial wall apparently.
Buzzlightyea - I have not seen any readings or evidence to suggest bridging between sockets & lighting.
Also Miss Marple won't talk to me after finding me in bed with Jessica Fletcher.
spinlondon - No powerlines
dmxtothemax - The issue really is the customer doesn't want to waste another 2 ton on a plumber to just walk away again and is adamant he wants the issue dealt with first
peg - Edit: Indeed on checking my volt pen lit up on both the approved pipes & approved joists and my voltage tester displayed voltage but of a negligable amount <12v ;-)
wilko - yeh. I agree. I only use my volt pen to trace cables in walls. (it's a 5v+ adjustable one imported from the u.s. and is brill at locating cables). I was just trying to put myself in the plumbers shoes to see what he was talking about. saying that it's never picked anything up on wood before hmmm.
marconi - I tested all the above with exception of boiler cpc at fcu which was a distance in the hall (boiler in the attic). I tested to the cpc at the boiler instead. I also tested with my megger (which is 10v+) but no reading as I presumed.
I'm going back soon to look at it again. I'm going to start by sorting the lights out due to the IR failure. It may be or may not be connected. Like I say it's not the first time I've found a screw ever so slightly piercing a live conductor and affecting the surrounding structure. The customer put a light up recently so it might be he's put screws into the ceiling and also the cable.
I'll let yous know how it goes and any findings.
Cheers & take care