RCD tripping

[CarolineWSL]

We have had a power cut in the area today and since then, I cannot get a ring main circuit breaker to stay on. The moment you flick the switch the RCD trips out. I have taken everything off the load and still the same problem. I have changed the CB and this is fine.

Can anyone shed any light on the problem? Any ideas what the problem can be or what I can try next?

Many thanks in advance for any advice given.
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[EFLImpudence]

Just to clarify - which device tripped first? Picture?

If it was/is the RCD then surely the (M)CB will stay on.

 

[CarolineWSL]

As soon as you turn the CB for that circuit on, the RCD trips out. There is nothing on the ring main at all !

 

[AndyPRK]

You got usb sockets build in, in your house?

You could guess roughly where the middle of the ring is.

Disconnect the live wires from the socket keep the two apart and insulated them in a block.

Then at the cu disconnect one of the live wires out the Mcb.

If the rcd won’t say on swap to the other wire. Assuming it now stays on

Work out which sockets are dead and with the power off loosen them. Looking for issues

 

[EFLImpudence]

As soon as you turn the CB for that circuit on, the RCD trips out.

Ok. So it's not the MCB that trips.
In other words the fault can be confined to ones that cause RCDs to trip but not MCBs.

Usually current from Neutral to Earth - water and Heating the most likely suspects.

I don't see how the power cut could be relevant but strange things do happen.

There is nothing on the ring main at all !

Are you absolutely positive?

No wet outside lights or sockets. Boiler, fans etc.

Has any work been carried out? Screws or nails in walls?

 

[EFLImpudence]

Disconnect the live wires from the socket keep the two apart and insulated them in a block.

It would be better to disconnect the Neutrals for an RCD - but not MCB - fault.

 

[CarolineWSL]

No USB sockets. Its a really old house and this section of electrics is really old! I have looked behind all sockets on the circuit and there is nothing obviously wrong - no loose connections etc.
Andy, can you please explain in a little more detail?

This is baffling me! Any advice greatly appreciated. Need to know what do try next..

 

[AndyPRK]

Well if there are 2 wires leaving the Mcb in cu and it’s a 32A it will be a ring.

You split it roughly in half by disconnecting approx. In the middle (furthest non functioning socket away from consumer unit) and one end to help understand where the issue could be.

Is your boiler still working ?

Pictures always help on here