Neutral insulation fault strange!

[sonobit]

Hi guys got a IR fault, basically there is a low IR reading on the upstairs sockets Live to neutral nothing strange there, but the rcd will only trip if the lights are switched on. so this is what happens i disconnect the lights and the upstairs sockets work rcd does not trip, then connect the lights still ok then flick any light switch and rcd trips. Disconnect the upstairs socket neutrals and everthing else works fine. Iam going to split the ring to find the fault but why would it affect the lights, is it an earth fault? any ideas guys? cheers i know you will want questions answering so ill do my best.

 

[Marvo]

0.9 Megs is borderline for most RCD's, tripping might only occur when there's a decent current flowing through it hence the tripping when the lights are switched on. I would just trace the fault in the normal way, identify the circuit, make sure it's not crossed or borrowed to another circuit then start splitting it up into sections.

 

[dagrat]

The 0.9mohms is between live and neutral and so should not trip the rcd as the rcd only picks up earth faults.

 

[Marvo]

Got my appointment booked at specsavers for 1.00pm.

The 0.9mohms is between live and neutral and so should not trip the rcd as the rcd only picks up earth faults.

I could only get a 1.30pm appointment, appears the opticians are busy this afternoon.

 

[telectrix]

i made my own out of the bottoms of 2 newcastle brown bottles ans some chicken wire.

 

[sonobit]

Thanks for the replies guys, i was leaning toward the earth fault when i was there i mean its an easy enough fix if i just split the upstairs ring and narrow down the fault and isolate it, that would probably solve the problem , but the lights are affected too and its narrowing down that fault which will require more investigation. But you know people they are just happy as long as the leccy is on. The problem is there is the meter which feeds a 80a RCD which then feeds 4 consumer units all old wylex fuse boxs, but the lights fuse box is located in a different place from all the other boxs. its a real mess of a wiring job, which makes my job that little bit harder, why dont people want PIRs done on new builds when the wiring has never been touched LOL. I hate the amount of times sparkys in the past have just added new fuseboxs or rcds of other circuits or straight from the mains and you then end up with loads of boards and switches and rcds all doing different jobs instead of just updating the consumer unit and keeping it simple.

 

[pushrod]

. I hate the amount of times sparkys in the past have just added new fuseboxs or rcds of other circuits or straight from the mains and you then end up with loads of boards and switches and rcds all doing different jobs instead of just updating the consumer unit and keeping it simple.

and never a diagram or explanation or results for the poor bugger who has to follow lol!