Rcd Keeps Tripping

[adam88]

Hi, I am an electrical contractor who works mainly in breweries. My friend rang me to say his Rcd kept tripping and it wouldn't stay on when he turned it back on.

I went round and he had already switched the 3 circuits off from the Rcd and unplugged all the appliances from both ring circuits. When I arrived the rcd with no load on was working correctly i.e the test button operated correctly. But with any of the 3 circuits turned on it would immediately trip.

I disconnected the L and N from the board for both the ring mains and found that I was getting continuity between the L and N from the downstairs ring. So we took all the socked and spur faces off everywhere downstairs. I then returned to the board and there was no longer continuity there so I put it down to that. But when I connected the ring back in the rcd would still trip.

He's had the house from new for 11 years and not had any problems before until now and said he hadn't done any work or anything out of the ordinary for this to happen.

I tried replacing the rcd but it didn't work. As I rarely work domestically I was wondering if anyone had any ideas.

The 3 rcd protected circuits are the upstairs and downstairs ring mains and an immersion heater.

Cheers

 

[m4tty]

Continuity between live and neutral wont cause rcd to trip. You need to properly test all 3 circuits doing cont and ir testing and test the rcd inc a ramp test would help. Can you get access to test equipment to do the tests?

Immersion heater could do with a test too as could be leaking to earth

 

[ProDave]

Check each circuit. in turn.  It's a L-E or N-E fault you are looking for.

Check other circuits not on the RCD also for N-E faults.

Basic testing really. the fact it's domestic makes no difference.

My money is on the immersion heater element failed.

 

[Steve3948]

Remove all the Neutrals and Earths from the connection blocks in the board before testing any or you may end up going round in circles.

 

[batty]

If the immersion is switched off at the switch and it still trips its not the immersion unless its wired wrongly.

 

[Doc Hudson]

Hi, I am an electrical contractor who works mainly in breweries. My friend rang me to say his Rcd kept tripping and it wouldn't stay on when he turned it back on.

I went round and he had already switched the 3 circuits off from the Rcd and unplugged all the appliances from both ring circuits. When I arrived the rcd with no load on was working correctly i.e the test button operated correctly. But with any of the 3 circuits turned on it would immediately trip.

I disconnected the L and N from the board for both the ring mains and found that I was getting continuity between the L and N from the downstairs ring. So we took all the socked and spur faces off everywhere downstairs. I then returned to the board and there was no longer continuity there so I put it down to that. But when I connected the ring back in the rcd would still trip.

He's had the house from new for 11 years and not had any problems before until now and said he hadn't done any work or anything out of the ordinary for this to happen.

I tried replacing the rcd but it didn't work. As I rarely work domestically I was wondering if anyone had any ideas.

The 3 rcd protected circuits are the upstairs and downstairs ring mains and an immersion heater.

Cheers

Welcome to the forum Adam. You say on your profile Panel builder. Do you actual do any work on RCD protected final circuits at all, commercial or industrial. The principals of an RCD are the same no mater where installed. It is leakage to earth that is detected. An RCD tester should be used to verify the RCD is operating correctly, i.e. not oversensitive. the Test button is only a very small part of verifying an RCD. You will also then need to verify insulation resistance between Live + Neutral to earth to try and identify any potential leakage current paths. As ProveDave suggests the immersion heater would be the first port of call as the most likely suspect. Water corrosion of element.

Doc H.

 

[IzzyS]

Remove all the Neutrals and Earths from the connection blocks in the board before testing any or you may end up going round in circles.

Take the neutrals out by all means, but leave the cpcs connected.  A nail through a cable making contact with the neutral and a damp wall will test out fine with everything pulled from the board.  That's why the regs and OSG say test with main earth and all cpcs connected.

 

[m4tty]

Wonder if this geezer has any power yet