How do I go about detecting this fault.....

[tommys88]

Basically yesterday I upgraded a fuseboard as the previous had no RCD protection so I installed a 17th edition split board.
Basically got board in, then one of the rcds would not set in with NONE of the breakers even switched on?! So i removed all the cables out of the neutral bar putting back one at a time to establish what was holding in etc established it was a problem with the kitchen ring!
Basically whenever the neutral and earth are connected in the board rcd won't set so if the earths are not connect ad neutrals are rcd holds vice versa! Does this mean there is an earth neutral fault somewhere on the ring?and is so what's the best way too find it?

 

[tommys88]

Yeah I know I understand this now but I want too rectify it so I'm trying too do what's right and follow advice on here! Iv done all the continuity tests and earth loops are all fine! Ir is coming up 0.00 iv got a megger multiple functional tester! I'm pretty sure iv unplugged everything but there is a lot of units which could be concealing power points?

 

[tommys88]

Also lucky enough they are putting in a new kitchen as they have just moved in so if worst comes to worst I can install a new kitchen ring without major dramas!

 

[Penance]

So you think you may be doing the ir test with equipment still attached? Really need to sort that before you do ir, just hope you've not damaged anything.
You know a kitchen ring is notifiable also?

 

[nikmet]

If you seperate the kitchen ring into small sections then IR each section, you will quickly locate the fault, then if need be, just renew the faulty section.

 

[telectrix]

your first step is to ensure all appliances are unplugged ( not just switched off ). then, if the fault is still there, split ring as said before and IR test each half. then split the faulty half in half again. quite possible to find a JB plastered in, nail through cable, short circuit to metal back box, and a few more i could mention when i've woke up properly.

 

[nikmet]

If you seperate the kitchen ring into small sections then IR each section, you will quickly locate the fault, then if need be, just renew the faulty section.

Becareful that the boiler is not still connected, it can be easily damaged with IR

 

[telectrix]

could even be the boiler causing the fault.

 

[KFH]

Apart from all the things recommended already. Have a look in every cupboard and behind drawers for sockets , FCUs etc. Also are there any lights in/around the kitchen units these are often connected into the ring somewhere, extractor fans, hobs, gas hob ignitors, all get connected into the ring by various means not always obvious or correctly, many of these do not like 500V up them.

 

[telectrix]

Apart from all the things recommended already. Have a look in every cupboard and behind drawers for sockets , FCUs etc. Also are there any lights in/around the kitchen units these are often connected into the ring somewhere, extractor fans, hobs, gas hob ignitors, all get connected into the ring by various means not always obvious or correctly, many of these do not like 500V up them.

which is a good reason to soft test at 250v.

 

[Des 56]

After the precautions mentioned
Here is a step by step aproach

Split the ring in the kitchen
Dis connect the faulty leg of the ring from the consumer unit L+N
The fault will be on one half or the other
Identify the outlets which retain the fault
It could be a local fault in the kitchen or supply cable,so disc onnect the socket that appears to be the one from the mains with the fault still on.testing (try using 250 volt) as you go, you will have narrowed it down to local or supply
Split more sockets if its local, until you get the nasty little bugger

Even though your a spark albeit not registered, for self certificating under part p,unless you notify and pay up for these sort of jobs,you will be committing an offence and could find yourself never ever getting into any bother, but inconveniances could "possible only" occur for house sale issues, because its not logged with labc