Broken CPC on ring final

[skamuk]

My friends downstairs sockets are tripping the RCD. First thing I did is unplug everything on the circuit, switched on the MCB and the RCD tripped. Tested continuity of L-L N-N CPC-CPC between the legs. CPC has no continuity whatsoever. Could anyone advise me what would be my next step to determine where the break in the cpc is? Thanks

 

[stuartcourt]

I take it only normal size house so safe way is to take off sockets one by one

 

[telectrix]

as above. wander lead from CU . find the break. then investigate the RCD problem.

 

[skamuk]

I take it only normal size house so safe way is to take off sockets one by one

Have done this. All connections are present and terminated ok. I now need to determine where the break is, bearing in mind all cpc are twisted together at each socket. Would I untwist all of them and test continuity between each socket?

 

[kingeri]

Break the ring into two roughly equal sections and test each, find the faulty half, then halve it again and so on until you find the fault.

 

[telectrix]

aarrrghh. twisted cpc's . the work of muppets.

 

[dan86]

Break the ring into two roughly equal sections and test each, find the faulty half, then halve it again and so on until you find the fault.

+1
its the quickest and easiest way.

 

[Geordie Spark]

aarrrghh. twisted cpc's . the work of muppets.

The Muppets: Bohemian Rhapsody - YouTube

 

[kingeri]

My post took about ten minutes to appear!

 

[Geordie Spark]

My post took about ten minutes to appear!

That's cos the postman's bike threw its chain.

 

[Octopus]

Steps to take:

1. Get MFT out of van
2. Identify all sockets on circuit - draw plan
2. Set MFT to Zs
4. Go to each socket in turn and note value

If you are lucky you may see a "significant" drop in value at adjacent sockets - then take each off the wall and look more closely.

 

[chris222]

I had same problem disconnect cpc from
board rcd may stay up hence earth problem with neutral somewhere only takes a nip on the neutral to trip them things as far,as finding break in earth like previous said break the ring in middle and test one by one

 

[skamuk]

Steps to take:

1. Get MFT out of van
2. Identify all sockets on circuit - draw plan
2. Set MFT to Zs
4. Go to each socket in turn and note value

If you are lucky you may see a "significant" drop in value at adjacent sockets - then take each off the wall and look more closely.

MFT wont do Zs, can do Ze and (r1+r2)/4... Seems like a long way round for me. I was planning to disconnect all cpcs on the circuit, untwist them all, then put wander lead on cpc leg 1 and test continuity at each socket, until I find the first socket in the ring, then do the same with the second cpc on leg 2 until I find the last socket in the ring. Once I've confirmed continuity between CU and first and last sockets I will move on to test cpc between each socket. Would this be the logical way to do it or a long way to do it?! - Also, would this not be the reason the RCD is tripping? Or will I need to locate a N-E / L-E fault somewhere as well? Thanks for your help everyone!

 

[skamuk]

I had same problem disconnect cpc from
board rcd may stay up hence earth problem with neutral somewhere only takes a nip on the neutral to trip them things as far,as finding break in earth like previous said break the ring in middle and test one by one

Will try this also, thanks.

 

[Octopus]

MFT wont do Zs, can do Ze and (r1+r2)/4... Seems like a long way round for me. I was planning to disconnect all cpcs on the circuit, untwist them all, then put wander lead on cpc leg 1 and test continuity at each socket, until I find the first socket in the ring, then do the same with the second cpc on leg 2 until I find the last socket in the ring. Once I've confirmed continuity between CU and first and last sockets I will move on to test cpc between each socket. Would this be the logical way to do it or a long way to do it?! - Also, would this not be the reason the RCD is tripping? Or will I need to locate a N-E / L-E fault somewhere as well? Thanks for your help everyone!

Really??