RCD tripping again!!!!

[MalcyB]

Hi All

I went to check out an RCD that was tripping out for no apparant reason. There was no clue to link it to any particular circuit. It was tripping about 6 times a day.

I checked the three ring mains, all tested ok I/R continuity. (I didn't have time to do any other circuits)

The Ze came in at 0.6ohms on a TNCS.

I also tested the RCD which stopped the auto test on 5x delta. 40ms. So I assumed the RCD could be faulty, so the next day changed it for a new one.

The lady said that since I'd checked it the day before, it hadn't tripped once.

After I put the new one in, I ran the tests again, it stopped on 5x delta again, since then this one hasn't tripped either.

This house and one across the road have got a bit of history, last year there were two neutral surges, the first blew the meters in both houses, the second blew a lot of the appliances in the second house but none in this. But since then his electric bill has shot up & British gas are saying he is using

 

[Andy™]

0.6 for PME is way too high - and if they are having problems with neutrals, id be tempted to change it for TT.

For the RCD tripping, could be number of things, including a fault on a circuit you didnt test

 

[binky]

0.6 for PME is way too high - and if they are having problems with neutrals, id be tempted to change it for TT.For the RCD tripping, could be number of things, including a fault on a circuit you didnt test

Or a dodgy appliance, but poor neutral could cause issues with test gear. I reacently had a similar experience whereby all Zs readings came in around 1800ohms, until DNO changed damaged supply box on outside wall.

Think I would take Andys' advice and TT for safety given history and ineffectuality of DNOs to fix problems!!!!