Earth Leakage

[slippyr4]

CPC definately isn't open circuit - cos i'm clamping it and seeing current, as opposed to finding some voltage on it.

Did some tests earlier. The fault seems to be on the 1st floor ring final.

Disconnected all load (unplugged everything), both phase, neutral and ME currents down to zero.

Plugged in just the kettle on this circuit. Clamping live showed about 12A, neutral about 2A and ME was the other 10.

I've tested and there's nothing wrong with the kettle.

This leads to an interesting conclusion- the impediance of the CPC from where i plugged the kettle in is lower than than of the neutral.

And clearly, if we increase the load on this circuit, then the current in the CPC could reach levels where it's overloaded (the circuit is a ring final in 2.5+1.5 T+E).

I've had a look behind a few of the sockets, and everything seems ok (except one of the kitchen ones has 2 spurs off it, a bit busy in the wiring terminals). Without taking the rest of them off i can't be sure, but i'm increasingly thinking that the likely fault involves a nail or screw in a wall or something.

I've exhausted how far I want to get involved with testing this (i'm not prepared to have the lid off the CU, although I would in my own house). so it's time to get a spark in methinks.

thanks for the input everyone.

slip

 

[ColJack]

they weren't sugesting that the CPC was open circuit, only that in the event that it did become disconnected, there would then likely be mains voltage on any exposed metalwork that was bonded etc..

since this is "work" and not domestic, then part P is not in effect so feel free to have the lid off and have a look... you seem pretty clued up as to what you'll be looking for.. though you might be missing some of the test gear to do it properly..

 

[ricicle]

Is this your place of work.Are you insured to do this work, for example, if you have an accident while fault finding.You need to be sure

 

[slippyr4]

I realise part p doesn't apply. I do have most of the test equipment i need - i rewired my house (with a building notice). But i'm not employed as a spark so I'm no getting involved in taking lids of consumer units and all that. not worth the bother.

cheers

Jon

 

[Spark123]

I'll agree with you on that, unless you can prove you are competent to prevent danger or injury (EAWR) etc then best not to touch.
Although Part P does not apply, the Health and Safety at Work Act, Electricity at Work Regulations, PUWER, COSHH etc do all apply to a commercial environment. Falling foul of any of the formentioned is definately not advisable!