RCD Fault

[RJS Contracts]

Hi guys, Got a bit of a problem with an RCD fault that cant get my head round!!!

Just done a board change and there were two pyros in one mcb that now trip rcd when turned on. Cant find any dead short on either cable and can only find one of them leading to a socket outlet.

Board is a sub main and is on rcd main switch so no possible neutral mix up!!?!!

Any ideas?

 

[pevvers]

Have you tried an insulation resistance test? Pyro is notoriously bad for insulation faults if it's installed badly...

 

[Deleted member 9648]

Try a 1000v IR test if the usual 500v one is inconclusive...I,ve known that show up a fault when a 500v test was clear on pyro's.
Edit...make sure there's not a computer on the other end though

 

[Guest123]

Did you have to re-pot them???

Were they bent back and fore a lot when you re-terminated them into the new CU???

Have you definately got correct polarity???

Sounds like an L-E fault for sure.

 

[RJS Contracts]

Didnt have time to delv into it today and left board isolated. Will look into it again tomorrow.Haven't re-potted them so could be that. Also just remembered that the sub main was quite strange. Wired in singles through conduit the live conductor was 4mm Neutral 6mm with an earth of 1.5mm being fed from a 32a mcb. Was thinking to pick it up on the test that new feed should be installed or at least a bigger earth!!