RCD Tripping on Downstairs...

[Mr T]

Evening All

My RCD wont reset on my downstairs ring main...

I have unplugged every appliance and no joy

I have tested N-E Insulation Resistance and get 470 Mohm

L-N 490Mohm

but L-E 2.1 Mohm

The RCD is fine when the downstairs ring MCB is off..

I have opened up every socket and spur and seperated the ring and tested each end between L-E and get reading all greater than 400 Mohm...

Any advice would be helpful...

 

[alpha spark]

Hey mr t had this problem a few month ago changed cu to 17th edition version the whole house ring was one circuit and has soon as I put it on a rcd trip trip trip tried unplugging every thing ended up leaving it on a mcb at a last resort and told client a further investigation is required trying to explain this to the home owner didn't go down too well everything has been ok for 10 years it's only since uve messed with it etc etc etc

 

[ProDave]

If every leg of the circuit tests okay then the fault has to lie within one of the socket outlets.

Test the L-E insulation of each socket outlet. If one has overheated and been arcing, it could well have insulation problems.

If not, double check your measurements of each leg.

It could of course have been a cable that was getting pinched between the socket and the back box, and removing all the socket fronts has removed that pinch.

 

[Mr T]

all ok for the time being , I reconnected 1 socket at a time to see if I could identify the dodgy 1 but no further trips from the RCD so maybe pinch between the socket /back as suggested above..

 

[OnOff]

Maybe where the T&E enters one of the metal back boxes it has chaffed if no grommet? Had that on a twin socket in a kitchen where the old couple unplugged the kettle umpteen times a day and the socket front was a bit loose...........