A Ring is causing breaker to trip

[Jupiter01]

I was helping my in-laws with an issue with one of their ring circuits. AS son as they switch the breaker on at the CU, it trips again. We only have 4 sockets on this ring and nothing was plugged into any of them. I unscrewed each of them and noticed the following:
- the earth wires (unsleeved) were burnt in two of the sockets (possibly next to each other in the ring sequence)
- all of them apart from one socket had power down both ends of the line wire. All others, only had power down one leg of the line
- I have continuity across Neutral and Earth but not Live.
- With one of the sockets, as soon as both Line wires go into the socket or even a wago connector (connecting the two together), it causes the circuit to trip.

I have temporarily resolved this by only connecting one of the live wires to this socket and terminated the other into a wago connector.

I know this will mean that we only have power down one leg of the ring.

Any suggestions on what may be causing this please? I am puzzled by why it only trips when connected to the other leg of Live and not when it is separated from it.

Look forward to your suggestions.

 

[AndyPRK]

Got a pic of the burnt bits ?

 

[Jupiter01]

I didn't take any pics. Sorry.
They were black and it rubbed off on my hands upon touching the unsleeved earth wires. I gave them a wipe and popped them into a sleeve before putting it all back together again.

 

[AndyPRK]

Are you saying the earth is shorted to neutral ?

 

[Jupiter01]

There were no visible signs of this. It may have happened under the floor or walls but I couldn't see any exposed neutral wire behind the socket.

 

[AndyPRK]

If you think there is damage to the cable between 2 sockets. (Where there is no live continuity) you could disconnect the N and L both ends and fit a 20 or 25A Mcb converting to radial

 

[Jupiter01]

Sure.
I am interested to understand the possible causes and whether there is an obvious issue based on the observations I have shared above please?

 

[EFLImpudence]

- all of them apart from one socket had power down both ends of the line wire. All others, only had power down one leg of the line

That doesn't make sense.

- I have continuity across Neutral and Earth but not Live.

Where?

With one of the sockets, as soon as both Line wires go into the socket or even a wago connector (connecting the two together), it causes the circuit to trip.

That shouldn't make any difference on a ring circuit, so there must be another line conductor disconnected somewhere and presumably shorting to Neutral or more likely Earth.


Is it definitely a ring circuit?

 

[oldbutnotdead]

A little more clarity...
First, is it an MCB or an RCD (or RCBO) that is tripping- pics will be easiest.
Second, presumably your continuity tests on N and E are showing 2 separate loop (not N and E connected to each other).
Finally, it is possible you have 2 breaks in the phase (L) conductor- the broken section is likely in contact with N or E so soon as you energise it you get a fault current
With power off, check all the cables where they enter backboxes (looking for cuts in insulation). After that its long lead on the meter time to find the dead bit.

 

[333rocky333]

- I have continuity across Neutral and Earth .

You will have, if the circuit is still connected in the Consumer unit, even though the individual circuit is off

 

[Taylortwocities]

- I have continuity across Neutral and Earth but not Live.

You must fully disconnect the circuit to make this test. Surely you know that earth is connected to neutral. Either at the incoming supply, or at the substation.

You’re going to need an Insulation Resistance tester. Got one?

 

[EFLImpudence]

- I have continuity across Neutral and Earth but not Live.

I think Jupiter meant he has continuity across Neutrals and across Earths but not across Lives - i.e. end to end.

 

[Jupiter01]

Thanks for all the responses. I also think my comment on live having power down 1 or both legs doesn’t make much sense. I don’t think I have tested this correctly. I will review this again and come back to you.

This is the circuit in question


I haven’t opened up the CU to check but assumed that it’s a ring because if I grab (with power switched off) 2 neutrals at any socket or 2 earths, my tester shows continuity. I assume this wouldn’t be the case with a radial?

Not withstanding my earlier comment on the need to go back and check the situation with the Live wires, I am definitely experiencing the following:
With one of the sockets, as soon as I join the incoming and outgoing live wires (in the socket or a wago connector), the circuit immediately trips. With all other circuits connected in this circuit, I checked power and could see that I only have power coming down one of these live wires. In the end, I’ve terminated the live wire without power into a wago connector and popped the other line into this socket.

I hope that sheds some more light on the issue. Thanks again