Fault on kitchen ring

[TheCodboy]

Hi all. Had a phone call about a tripping RCD. The customer had narrowed it down to the kitchen ring. When I go there,it was indeed the kitchen ring causing the tripping. Firstly checked the usual,nothing plugged in to any of the sockets. Checked the connections at the sockets,these were all fine. Checked end to ends,had continuity on L,N & E. Carried out IR between LN & E at 250v,very low reading,virtually zero. Also tested L-E N-E & L-N. All very low. Now,the cables in the kitchen are red/black and the cables at the board are Brown/Blue. There no sign of any crimps etc at the board (which by the way is a total mess). So I’m thinking hidden joints/jb could be the source of the problem?? Any pointers would be appreciated!

 

[Midwest]

Nah, it'll be an existing socket(s) from the previous kitchen install, buried under some tiles/plaster somewhere. If fault finding, gonna take longer than running in some new cables, I'd be tempted to do that.

 

[TheCodboy]

Nah, it'll be an existing socket(s) from the previous kitchen install, buried under some tiles/plaster somewhere. If fault finding, gonna take longer than running in some new cables, I'd be tempted to do that.

This was my thought. Much quicker & easier all round.

 

[Dobes_88]

Any outside sockets potentially on the circuit?

 

[TheCodboy]

Any outside sockets potentially on the circuit?

None that I can see and the customer reckons there’s just the 3 sockets in the kitchen itself. No visible fcu’s etc.

 

[Wilko]

None that I can see and the customer reckons there’s just the 3 sockets in the kitchen itself. No visible fcu’s etc.

Hi - yes been told this by Customer a few times . Perhaps safely isolate and test L-N, first IR (250V). If IR is big, then ok - no loads still connected. If small, do continuity and if this is not o/c you should keep looking. Domestic loads typically range from about 20 Ohms to 20k Ohms. Some little device may still be connected and be faulty. Not saying its not a cabling fault, just another idea .

 

[TheCodboy]

Hi - yes been told this by Customer a few times . Perhaps safely isolate and test L-N, first IR (250V). If IR is big, then ok - no loads still connected. If small, do continuity and if this is not o/c you should keep looking. Domestic loads typically range from about 20 Ohms to 20k Ohms. Some little device may still be connected and be faulty. Not saying its not a cabling fault, just another idea .

I’ve IR tested at 250v,readings come back at virtually zero. Not even high enough to suggest anything still connected.

 

[Wilko]

I’ve IR tested at 250v,readings come back at virtually zero. Not even high enough to suggest anything still connected.

Hi - Many IR testers fall in a heap when presented with a low impedance and tell you it's zero. My continuity tester will happily tell me 150 Ohms when there's a lamp still in circuit. But try that with the IR and it's zero. If I did IR only I'm chasing a cabling fault ... continuity result tells me there's likely a load still connected.

 

[TheCodboy]

Hi - Many IR testers fall in a heap when presented with a low impedance and tell you it's zero. My continuity tester will happily tell me 150 Ohms when there's a lamp still in circuit. But try that with the IR and it's zero. If I did IR only I'm chasing a cabling fault ... continuity result tells me there's likely a load still connected.

The problem is,I’m getting some horror stories of diy Dave striking at this house. There’s a very good chance that there’s possibly more sockets hidden behind kitchen units etc. Some of the things that the owner told me about when they bought it the place...... I’ll double check that there isn’t an outside light or something. Apart from that,it would mean ripping the kitchen to bits!!

 

[TheCodboy]

Hi - Many IR testers fall in a heap when presented with a low impedance and tell you it's zero. My continuity tester will happily tell me 150 Ohms when there's a lamp still in circuit. But try that with the IR and it's zero. If I did IR only I'm chasing a cabling fault ... continuity result tells me there's likely a load still connected.

Normally my fluke will give a reading that indicates a load still connected. It will slowly start to rise then stop.

 

[Strima]

Set at 1000 volts and watch for smoke/flames...

 

[TheCodboy]

New ring going in next week. I’ll try get a picture of the board while I’ve got the lid off..... I’d love to hear from some of the older guys to see if it’s one of the worst they’ve seen!!

 

[Pete999]

New ring going in next week. I’ll try get a picture of the board while I’ve got the lid off..... I’d love to hear from some of the older guys to see if it’s one of the worst they’ve seen!!

Look forward to it.

 

[Octopus]

This was my thought. Much quicker & easier all round.

Hum .............. do the job properly .......... locate the fault then decide what to do next.

 

[TheCodboy]

Hum .............. do the job properly .......... locate the fault then decide what to do next.

I’m sure the customer would rather I didn’t start dismantling kitchen units to look for jb’s and/or sockets that no one knows are there,if they are there at all.

 

[littlespark]

You test each leg at every socket. If there’s a hidden jb or socket behind a cupboard and it tests ok just leave it. Not ideal, but they might change the kitchen again before a problem arises.
Think rewiring the whole rfc is a bit much when it could be just one bad connection somewhere.