Finding short circuit on ring main

[Nero]

Hi all.
I have a ring main of 5 double sockets and the RCD is cutting instantly when switched on. I'm thinking there must be a short circuit in the cable between the sockets.
Probably pretty basic but how do I determine which part of the circuit it is so I can rewire just that part?
Thanks

 

[EFLImpudence]

Is the RCD only covering this one circuit?

 

[Nero]

Yes.
Nothing is plugged in to any of the sockets. It has been ok for years and just tripped randomly and wouldn't switch back on. Possibly mouse has chewed through cable but this is just assuming!

 

[EFLImpudence]

The normal way is to split the ring somewhere near the middle and disconnect one side of the ring at the consumer unit.

If you don't want to go into the CU, and as there are only five sockets, you could, if you know the circuit route, disconnect the first and last sockets and separate all the pairs of wires at both sockets.

If the RCD still won't reset, then the fault must be in one of the legs from the CU, in which case you will have to go into the CU and disconnect one side.
It might be difficult to tell which side is which so if it still trips disconnect the other side and reconnect the first. Reconnect one socket and see if it works, if it does then you have disconnected the faulty cable to the other side.

If the RCD will reset with the two sockets disconnected then the fault must be in the cable between the first and last socket.
Reconnect one of the original two disconnected sockets and by a process of elimination by disconnecting any of the other three sockets you will be able to find the length of cable with the fault.

Draw the circuit and record what happened or you will get muddled up.

 

[EFLImpudence]

It could be just a pinched wire, likely a Neutral, by one of the socket screws which has finally, with movement of plugging and unplugging, made contact with the actual copper conductor.
This is probably not the case with a single circuit on an RCD, but you never know, something might be different than you think.

 

[Nero]

Thanks. this is really helpful. I will give it a go.