Fault finding ring..

[SUFCDAN]

Hello, I have fitted som new cabinets in my kitchen, there Is quite a few cabinets wall and floor, I disconnected all the socket fronts and put them back correctly.

The it’s now tripping the main breaker, I have isolated the mains and removed the pair of Twin and earth from the 32 amp breaker, (nothing is plugged in, in the kitchen). On one of the cables at the CU neutral, earth and live have continuity! the other cable is fine.. so have I wired up something wrong, or have chopped/screwed through something.

What’s the best way to trace this please, I have a fluke meter and a continuity tester that has a fly lead to test remote polarity.

Thank you.

 

[JohnW2]

Hello, I have fitted som new cabinets in my kitchen, there Is quite a few cabinets wall and floor, I disconnected all the socket fronts and put them back correctly. The it’s now tripping the main breaker ...

What exactly is tripping? It is an MCB (probably labelled 32A or B32) or an RCD (with a test button)?

.... so have I wired up something wrong, or have chopped/screwed through something.

Circumstantially, the latter would seem the more likely!

Kind Regards, John

 

[conny]

First isolate that circuit at the CU. Then go round each individual socket and remove the fascia, take a careful look at the cables behind each one. You are looking to see if a wire has been trapped by the fascia screws, It may be just a flattened area that doesn't seem to have a break in the insulation but you will need to cut it back if it does, (hopefully there will be enough slack to do this). After carefully replacing the fronts, leave the screws slack and try to restore power. If the breaker stays in turn off the power and tighten each front properly but reset the power after each one. If it trips again you will know which socket is causing the problem.
It's a long winded way of doing it but an easy way.

 

[JohnW2]

.... You are looking to see if a wire has been trapped by the fascia screws, ... It's a long winded way of doing it but an easy way.

All true, if such is the nature of the problem.

However, since this problem arose when the OP fitted some new kitchen cabinets, there are obviously other possible explanation which has nothing to do with anything going on in the vicinity of the sockets.

Kind Regards, John

 

[AndyPRK]

The fact that the 2 ring wires are different and not complete does sound like a drill has caused problem.

There is the split half technique where u goto the middle of the kitchen ring and understand which side the fault is and work one way.

Or if the 2 earth cables don’t have continuity at cu you can probe between the 13A earth pin and the next skt and see where continuity stops.

Or where have you been drilling last!

 

[JohnW2]

The fact that the 2 ring wires are different and not complete does sound like a drill has caused problem.

As I've been saying, that certainly seems like a reasonable possibility. As for exactly what the OP has discovered, I don't really understand the meaning of ...

... On one of the cables at the CU neutral, earth and live have continuity! the other cable is fine..

... do you?

Kind Regards, John

 

[AndyPRK]

I read it as 3 wires are shorted together on one cable.

But not the other

 

[JohnW2]

I read it as 3 wires are shorted together on one cable. But not the other

That's certainly one way of interpreting it.

If that were the case, not only would an attack on the cable have had to have managed to short all three conductors together, but at least two of the conductors would have had to be broken at that point ('downstream' of the short) - since, assuming the ring was otherwise intact, there would otherwise be 'continuity' between at least two of the conductors at the other end of the ring. However, nothing is impossible.

Kind Regards, John

 

[SUFCDAN]

That's certainly one way of interpreting it.

If that were the case, not only would an attack on the cable have had to have managed to short all three conductors together, but at least two of the conductors would have had to be broken at that point ('downstream' of the short) - since, assuming the ring was otherwise intact, there would otherwise be 'continuity' between at least two of the conductors at the other end of the ring. However, nothing is impossible.

Kind Regards, John

The puzzle,


Thank you all for replying, I did not explain clearly enough, so one of the ring ends is tripping the RCD, I have removed both cables from the MCB, This is what is get,

From the cable that is tripping,

Earth has continuity with the other cables live and earth, not neutral.

Neutral has continuity with live and earth, not the other neutral.

Live has continuity with live and earth, not neutral.

On its own the bad ring cable, all live(red) earth and neutral (black) all have continuity.

On the other earth and live have continuity...

Are wires swapped around or trapped,

Thank you all again for the help.

 

[EFLImpudence]

Have you also removed the two neutrals and two earths from their respective bars in the consumer unit?

 

[JohnW2]

T... one of the ring ends is tripping the RCD, ...

If only one of the ends is tripping the MCB then the ring must be incomplete. If you have ruled out things not connected properly at the sockets on the ring, that must mean that the cable has been 'chopped' somewhere.

On its own the bad ring cable, all live(red) earth and neutral (black) all have continuity.

I presume you mean that all three have continuity with oine another. If that is the case then, as I said before, the cable must not only have at least two of it's conductors broken somewhere, but something must be shorting them together (on the CU side of the break). Drills and screws would seem the most likely culprits.

Are the heads of screws that you have recently pout into the walls all 'accessible'?

As EFLI has said, you should remove the neutrals and earths of the cables concerned from the bars in the CU (as well as removing Ls from the MCB) when you measure - although I doubt that would alter my 'interpretation' above.

Kind Regards, John

 

[Harry Bloomfield]

If only one of the ends is tripping the MCB then the ring must be incomplete. If you have ruled out things not connected properly at the sockets on the ring, that must mean that the cable has been 'chopped' somewhere.
I presume you mean that all three have continuity with oine another. If that is the case then, as I said before, the cable must not only have at least two of it's conductors broken somewhere, but something must be shorting them together (on the CU side of the break). Drills and screws would seem the most likely culprits.

Are the heads of screws that you have recently pout into the walls all 'accessible'?

As EFLI has said, you should remove the neutrals and earths of the cables concerned from the bars in the CU (as well as removing Ls from the MCB) when you measure - although I doubt that would alter my 'interpretation' above.

Kind Regards, John

A possible way to save time, if it is a screw fixing causing the issue, is to check for continuity between the various screw heads and the cable end where the short is showing, using a long length of wire between meter and screws.

 

[JohnW2]

A possible way to save time, if it is a screw fixing causing the issue, is to check for continuity between the various screw heads and the cable end where the short is showing, using a long length of wire between meter and screws.

Quite so. If the reason was not obvious, that's why I asked ...

Are the heads of screws that you have recently pout into the walls all 'accessible'?

Kind Regards, John

 

[SUFCDAN]

Guys... I’m back and thank you all, it was something really silly I did.....the said socket..

I joined them with a wago 77-106 6 terminal!!!! I thought, and don’t laugh, the the terminals joined parallel, so red to red, black to black and so in... not all together.... I wonder why they don’t make one, instead of using 3 separate 22-412 double pin. Regards x

 

[oldbutnotdead]

There's still a potential issue there- both legs coming back to the CU should have shown the same fault (everything shorted out). They didn't, therefore your ring is not complete. Well worth sorting out while covers, sockets etc are off