RCD problem

[yelloperil]

Hi All, I am having problems finding a fault and would appreciate any ideas, I have got an RCD on a ring main and on some sockets all tests are great but on some sockets the RCD is tripping at greater than 40 ms on 5x test any ideas?

 

[Deleted member 26818]

Yes.
Test at the board.
Your test results are being affected by volt drop, and the resistance of conductors and equipment between where you are testing and the RCD.

 

[isitnow]

as spinlondon said test at the board, you dont have to test rcds out in the field also saves you walking back and forth lol

 

[Silly Sausage]

Have you done your ring continuity and IR tests to prove the ring is OK or otherwise?

 

[yelloperil]

Thamks guys, I have now done some more tests and the ir is low between the N and CPC so I have got other issues to rectify.

 

[telectrix]

how low do you call low?

 

[yelloperil]

0.48 between N/CPC Greater than 299 between CPC/Live and greater than 299 between live/N

 

[Deleted member 26818]

I take it, that you've disconnected the CPC from the board when conducting the IR test?

 

[ackbarthestar]

RFCs can sometimes be directly or indirectly cross bonded to other circuits, neutrals can also be shared across circuits. You may have isolate and disconnect both cpc and neutral from the board.

 

[Knobhead]

Just looked at some of his previous post………….. Oh dear!

 

[ezzzekiel]

Chances are a neutral is nipped by a socket somewhere