Ring main troubleshooting

[ericmark]

Have a guess at likely route of ring final. With power off remove two sockets one likely to on clockwise near to consumer unit, one likely to be on anti clockwise so you now have two sections.

One will go vir the CU, the other with be isolated from CU, with your tester find out which still has fault. You have now isolated the fault to a part of the ring final, depending on which section is next step, if fault seems CU side then again guess on a socket nearer to CU is not the aim centre of ring.

I am sure you can see the idea, if not then best you don't do the work.

 

[Harry Bloomfield]

Yes, I can understand that in principal but I am unsure how it is precisely achieved.

If it's a ring, there will be two browns (or reds), two blues (or blacks), and two earth wires - each going into one of the terminals, in the consumer unit. A ring goes, from the consumer unit, around several sockets, then back to the consumer unit - which is how there are two of each conductor, at the terminals. You are going to have to disconnect the terminal you are struggling with, and probably others, in order to determine where the issue is.

 

[Murdochcat]

If it's a ring, there will be two browns (or reds), two blues (or blacks), and two earth wires - each going into one of the terminals, in the consumer unit. A ring goes, from the consumer unit, around several sockets, then back to the consumer unit

Quite. Then first you need to determine if in fact it’s a ring by checking continuity of each of the conductors.

Many 2 cables at the circuit breaker are in fact a radial circuit

The best type of fault finding doing things in a systematic way. Random approaches rarely get the job done

If as you say nothing has changed, no diy done, then the problem could be anywhere, caused by a number of different things, some very obvious, others completely invisible

 

[333rocky333]

If its tripping in the mini CU as well then its unlikely you need to even access the main CU

 

[KPX33]

Thing is, CUs do not
Yes apologies the MCB for garage supply trips.
The mini CU MCB for sockets ,simultaneously trips.

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trip. Some device inside them does. People need to know what is written on that device.

 

[KPX33]

If it's a ring, there will be two browns (or reds), two blues (or blacks), and two earth wires - each going into one of the terminals, in the consumer unit. A ring goes, from the consumer unit, around several sockets, then back to the consumer unit - which is how there are two of each conductor, at the terminals. You are going to have to disconnect the terminal you are struggling with, and probably others, in order to determine where the issue is.

Thank you, yes it is certainly a ring, it has 8 sockets, no spurs or other extensions whatsoever. All sockets are readily accessible.
Do you mean the terminals in the mini CU ? because I am unable to unscrew them due to excessive tightening by previous installer

 

[KPX33]

Yes apologies the MCB for garage supply trips.
The mini CU MCB for sockets ,simultaneously trips.

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[Harry Bloomfield]

because I am unable to unscrew them due to excessive tightening by previous installer

You will have to find some way, to split the ring, at least to begin with, in two locations, in order to carry out your tests...

Assume your sockets are numbered 1 to 8, going around from the CU. Disconnect 1, and 4 - then using your meter, check whether the fault is between 1 and 4, or 5 and 8. Assuming it is on 5 to 8, disconnect at 6, and then test for fault between 5 and 6, and 7 and 8. Repeat, halving, and quartering the ring, until you have isolated the fault down.

 

[ericmark]

You will have to find some way, to split the ring, at least to begin with, in two locations, in order to carry out your tests...

Assume your sockets are numbered 1 to 8, going around from the CU. Disconnect 1, and 4 - then using your meter, check whether the fault is between 1 and 4, or 5 and 8. Assuming it is on 5 to 8, disconnect at 6, and then test for fault between 5 and 6, and 7 and 8. Repeat, halving, and quartering the ring, until you have isolated the fault down.

I tried to give same instructions, I do not want to try to give step by step instructions, only a guide as to how, as if he can understand the guide then likely safe doing the work, if not then likely has not got the skill to do it safely. However he will need some test equipment and without it the whole exercise is pointless, and depending on what equipment is available can change how tested. Since it is the MCB which trips

I have included a picture so he can confirm it is the MCB which will not have a test button, the fault should show on any continuity tester. Using the leads in the clamp on meters shown likely and use buzzer function to find such a large fault.

In the same way as I use pictures if @KPX33 showed pictures maybe we would have a better idea of how to test.

 

[Murdochcat]

Yes apologies the MCB for garage supply trips.
The mini CU MCB for sockets ,simultaneously trips.

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With the Mini Cu switched off can you reset the other RCD?

It’s not usual to connect a cu to a ring circuit

 

[Harry Bloomfield]

However he will need some test equipment and without it the whole exercise is pointless, and depending on what equipment is available can change how tested.

OP sounds to have a multimeter, which should respond to help locate a dead short.

 

[KPX33]

You will have to find some way, to split the ring, at least to begin with, in two locations, in order to carry out your tests...

Assume your sockets are numbered 1 to 8, going around from the CU. Disconnect 1, and 4 - then using your meter, check whether the fault is between 1 and 4, or 5 and 8. Assuming it is on 5 to 8, disconnect at 6, and then test for fault between 5 and 6, and 7 and 8. Repeat, halving, and quartering the ring, until you have isolated the fault down.

Thank you, I will do that today.

 

[KPX33]

With the Mini Cu switched off can you reset the other RCD?

It’s not usual to connect a cu to a ring circuit

Yes I can & it remains "On"

"It’s not usual to connect a cu to a ring circuit"
Why is that please ?

 

[KPX33]

I tried to give same instructions, I do not want to try to give step by step instructions, only a guide as to how, as if he can understand the guide then likely safe doing the work, if not then likely has not got the skill to do it safely. However he will need some test equipment View attachment 333516View attachment 333517 and without it the whole exercise is pointless, and depending on what equipment is available can change how tested. Since it is the MCB which trips View attachment 333519I have included a picture so he can confirm it is the MCB which will not have a test button, the fault should show on any continuity tester. Using the leads in the clamp on meters shown likely and use buzzer function to find such a large fault.

In the same way as I use pictures if @KPX33 showed pictures maybe we would have a better idea of how to test.

Understood, thank you

 

[Jurassicspark]

"It’s not usual to connect a cu to a ring circuit"
Why is that please ?

Get an electrician in.
Splash some money.