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?

 

[topquark]

Pretty much, could be either earth->neutral or line->neutral though. Make sure all of the appliances are disconnected in the kitchen and retry. If it still trips immediately then visual inspection of all the sockets again and look very carefully for small nicks etc in the inner core insulation.

 

[Penance]

What test equipment do you have, did you complete any testing before changing the cu?

Have you notified building control?

 

[johnboy6083]

first of all, i wopuld split thering, and start testibg from there, IR test between conductors. when youve found theside of the ring with the problem, then split that side in 2, until you find the problem. when found, do a full set of tests to ensure no cross connnected rings ect.


testing should be carried out on an installation before a board change, to ensure that this doesnt happen!

 

[keniff]

If you have a tester do an insulation test neutral to earth see if it's a low reading

 

[tommys88]

Yeah I should of said I took all the sockets off no nicks or anything like that visible unfortunately! How do I establish which fault it is line-neutral line-earth or neutral-earth fault? Then best way is just to split it in the middle and trace each leg is that right?

 

[londonlec]

Are you an electrician?

 

[malcolmsanford]

Un plug everything on the ring final, and if there are FCU on them then turn these off, then at 250v do a L/N-E IR test and see what you get.

If you get a low IR reading and you have made sure everything is disconnected then break the ring somewhere in the middle. Then do another IR test on both legs, this will then narrow it down further and you just keep on doing this

 

[IQ Electrical]

Yeah I should of said I took all the sockets off no nicks or anything like that visible unfortunately! How do I establish which fault it is line-neutral line-earth or neutral-earth fault? Then best way is just to split it in the middle and trace each leg is that right?

You do it with insulation resistance tests as you would on a newly installed circuit.

Have you done any testing at all on this work?

 

[Octopus]

What were your IR readings?

 

[Des 56]

Yeah I should of said I took all the sockets off no nicks or anything like that visible unfortunately! How do I establish which fault it is line-neutral line-earth or neutral-earth fault? Then best way is just to split it in the middle and trace each leg is that right?

No,the fault will still be in circuit

 

[tommys88]

Yeah I'm an electrician only been qualified a year, it's thorugh my own naievty I don't usually do private work but as I favour I said I would upgrade there board for them as a favour thinking straight swap teat after lovely..... But obviously bit and um learning from my mistakes now!

 

[nikmet]

Yeah I'm an electrician only been qualified a year, it's thorugh my own naievty I don't usually do private work but as I favour I said I would upgrade there board for them as a favour thinking straight swap teat after lovely..... But obviously bit and um learning from my mistakes now!

what test instruments do you have / are you using?

 

[topquark]

Then start from scratch as you'll have the correct equipment. Visual inspection first, end-end continuity of conductors, ring continuity tests. BEFORE you do any IR testing please.

 

[IQ Electrical]

Yeah I'm an electrician only been qualified a year, it's thorugh my own naievty I don't usually do private work but as I favour I said I would upgrade there board for them as a favour thinking straight swap teat after lovely..... But obviously bit and um learning from my mistakes now!

You can't take a consumer unit change lightly, more fires start in the consumer unit than anywhere else, testing is very important!

Then you need to issue an Electrical Installation Certificate and notify the work to Building Control under Document P regulations.

 

[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.