Fault on refurb job

[J.C.E]

what a day I had yesterday! everything seemed to go wrong- after a heavy weekend- just what I needed- got myself extremely stressed out and wound up lol

ok job is a refurb+ kitchen+loft extension- so a mixture of old circuits and new circuits with a new dual RCD board.

board has been in now for over 3 weeks now with all circuits connected and being turned on as I 2nd fix- house- house is empty ect. And had no problems/trips until yesterday...

Got to one of the last circuits to be 2nd fixed and liven up (apart from kitchen ring)
- the downstairs lighting circuit

now when I apply load (it was a kettle) to the downstairs sockets (so on different rcd to downstairs lights- I just finished 2nd fixing)
the rcd with the lighting trips but rcd that protects the sockets that the kettle is plugged into doesn't and the kettle stays on

I didn't have my tool bag with testing gear in it yesterday as I lent it to my mate- but am back at the job tomorrow to pull some more hair out and test!

Does this sound like a mixed neutral somewhere (poss in cu- although I am 99.9% sure its not here, or poss in one of my hall/landing 2way switches- where some of them have multiple circuits in them (from apposing rcd sides of the cu)

I know I have not given much to go on in terms of readings etc- just seeing if any of you guys had some recently similar faults- so I could try minimized time haunted the b******* down.

cheers guys

Joe

 

[Wilko]

Hi J, hearing "the other RCD trips" I think it's one of 2 things. A swapped neutral as you say, or a N-E fault on a circuit that's controlled by the RCD that trips. Did they have RCD before? If it is the N-E fault on the other RCD scenario, load in that circuit should also trip the RCD in the usual way. Just a thought

 

[Octopus]

I would clamp the tails to get a handle off the earth leakage. It could be a fault on 1 RCD affecting the other one.

 

[J.C.E]

I would clamp the tails to get a handle off the earth leakage. It could be a fault on 1 RCD affecting the other one.

not actually got a earth leakage tester!
just a case of clamping the L+N tail of each rcd and turn a circuit on at a time- doing this might locate my circuit- then break it down down there?

 

[tomspark93]

Have you carried out any insulation resistance tests yet?

 

[Octopus]

not actually got a earth leakage tester!
just a case of clamping the L+N tail of each rcd and turn a circuit on at a time- doing this might locate my circuit- then break it down down there?

I would start by clamping the main tails before the CU to see what's going on..

 

[J.C.E]

I would start by clamping the main tails before the CU to see what's going on..

the house is still not been moved into yet- its still a bit of a work site- no appliances plugged in- just a few tools and extension leads- that I unplugged- but still no joy

so possibly seems to be more a N-E wiring fault- rather than earth leakage?

 

[Octopus]

so possibly seems to be more a N-E wiring fault- rather than earth leakage?

It would still show up on the clamp meter.... given the property is empty, then its got to be a N-E fault, or possibly 2, one on each RCD......

 

[Richard Burns]

If the RCD on the lighting circuit trips then there is a fault on the lighting circuit, or if that RCD is also protecting other circuits, a fault on any one (or more) of the circuits protected by that RCD.