As I said on another thread, I was doing a mock EICR and fault find today for a friend. She's in a 1900ish house with various extensions and partial rewires and has had trouble with nuisance tripping of the RCD (ELCB as I now find it is). Said I'd take a look for the experience of it and run a few tests to get used to my shiny new tester.
Day started off by finding that the DNO had sealed the MET enclosure for some reason... No-one seems to know why.
A couple of hours later I turned the power off, only to find that it set off the burglar alarm... and the code I'd been given didn't work! Half an hour later it finally shut up so I disconnected it completely (they didn't want it anyway!).
I did the tests, had the usual problems involving things being left plugged in, hidden behind wardrobes etc but all seemed to be going fine. Found a less than ideal IR results, but then it was to be expected.
Still didn't find the reason for the nuisance tripping. I'd been told it tended to happen when the heating was running, usually after 20 minutes or so, so I fired up the boiler. 2 minutes later, BANG! Not only did the ELCB trip, but so did the breaker on a lighting circuit...
I've run the IR tests again on that circuit and I'm now getting constant fails between line and neutral.
I've not disturbed anything at all, except at the DB end where all looks good, but I'm getting a resistance reading between line and neutral of 16 ohms.
Anyone got any ideas for me? Apparently the heating hasn't been used for a couple of years because of the problems it was causing, they've been making do with electric heaters instead. Reckon it could be a case of cables run next to a heating pipe and the insulation has just degraded to the point that it's given up the ghost? Although this place has evidence of a couple of partial rewires, the lighting circuits are mainly in black rubber coated cabling (pulling down the ceiling roses shows that the insulation is in a really bad way...)
Day started off by finding that the DNO had sealed the MET enclosure for some reason... No-one seems to know why.
A couple of hours later I turned the power off, only to find that it set off the burglar alarm... and the code I'd been given didn't work! Half an hour later it finally shut up so I disconnected it completely (they didn't want it anyway!).
I did the tests, had the usual problems involving things being left plugged in, hidden behind wardrobes etc but all seemed to be going fine. Found a less than ideal IR results, but then it was to be expected.
Still didn't find the reason for the nuisance tripping. I'd been told it tended to happen when the heating was running, usually after 20 minutes or so, so I fired up the boiler. 2 minutes later, BANG! Not only did the ELCB trip, but so did the breaker on a lighting circuit...
I've run the IR tests again on that circuit and I'm now getting constant fails between line and neutral.
I've not disturbed anything at all, except at the DB end where all looks good, but I'm getting a resistance reading between line and neutral of 16 ohms.
Anyone got any ideas for me? Apparently the heating hasn't been used for a couple of years because of the problems it was causing, they've been making do with electric heaters instead. Reckon it could be a case of cables run next to a heating pipe and the insulation has just degraded to the point that it's given up the ghost? Although this place has evidence of a couple of partial rewires, the lighting circuits are mainly in black rubber coated cabling (pulling down the ceiling roses shows that the insulation is in a really bad way...)
