New CU, RCD tripping when resetting CB

[Norv]

Changed a CU today. Switched it back on & the RCD tripped when I reset one of the Ring CB's .

I admit I only did a r1,r2,rn test (0.50, 1.48, 0.52) & an IR test (P+N joined & tested across to CPC). on this circuit (& the others). I know I should have done a proper PIR, but this time when I inspected sockets & lights the installation looked tidy, but dont slate me!

I also had the shower, another ring, & cooker on the RCD side but their CB's were off. Would it affect the RCD tripping with these still connected but not switched on or would the problem be definately on the ring in question ?

 

[daytona]

borrowed neutral?

neutral in the wrong bar?

 

[Norv]

neutral in correct bar, i double checked

If it was a borrowed neutral, I guess I would dissconnect all the neutrals & connect the problem circuit only to see if it tripped the RCD ?

 

[SeanT]

I'm no expert, and might be talking poo, but I'd have thought that an N-E fault could trip the RCD with just the live isolated?

 

[daytona]

just dis the neutrals one at a time and see what does it,and take it from there.def a nicked neutral from somewhere.

 

[daytona]

i assume all appliances and equipment are uplugged?

not a stray spur in a cupboard feeding something dodgy is it?

 

[Norv]

i assume all appliances and equipment are uplugged?

Just before I left tonight I was looking around the kitchen cupboards & noticed a piece of wood which looked like the back of the cupboard. I pulled it forward and there was an extension lead full of plugs behind it. Didnt have time to do anything else so I'll have a better look tomorrow. Thanks for the suggestions though

 

[333rocky333]

I also had the shower, another ring, & cooker on the RCD side but their CB's were off. Would it affect the RCD tripping with these still connected but not switched on or would the problem be definately on the ring in question

IMO
If there was load on the ring, possibly it could, not be the ring
If there was a slight neutral to earth fault on say the cooker circuit, with the mcb OFF.
Any neutral load from a good circuit , would only part return via the rcd , a slight amount though would pass up the faulty neutral and go to earth.

Therefore the higher the load on the good circuit, the greater the load not returning via the rcd neutral.
Causing possible tripping of rcd.
Carry out an insulation test from rcd neutral bar to earth with all neutrals connected

 

[daytona]

cmon norv!
what was it?

 

[Norv]

Well.............. I still dont know

This is a good example of people not regarding a fault as serious. Because its been working for the last 15 years they think its ok.

I had a phonecall at 7.45 this morning & was told not to come today.

 

[daytona]

thats out of order mate

not even a chance to put things right.leave them to it,dont forget to bill it