Dodgy micc

[Pete/2472]

Evenin all, just wondering if anyone can fix this one!
installed a new c/u today 36 way tp+n and removed four old 3036 sub boards all circuits in micc so the problem started when one of the rcbo woundnt hold? all circuits in the new c/u sockets on rcbos and lights on mcbs..carried out all dead tests and the end to end on all micc rings where fine except the one which is not holding which gives 768ohms across line + N, any ideas please as i need to get it on by the mornin and have lost the will to live.

 

[Guest123]

Hi there.

It might be a silly question but as it was L-N....was everything unplugged when you tested???

768ohms is absolutely fine though, and wouldn't cause the RCD element of an RCBO to trip

Sounds like a short circuit there somewhere though.

 

[Aok1]

A mate of mine had a simlar problem a while back, one of the cables had got quite damp for some reason. Also the obvious of a dodgey termination or damage.

 

[Pete/2472]

Hi there.

It might be a silly question but as it was L-N....was everything unplugged when you tested???

768ohms is absolutely fine though, and wouldn't cause an RCBO to trip

Hi Lenny its a large clinic with approx 25-30 rooms 1/2 were locked with no keys for access! but they told me everything was unplugged! i think they thought i was changing lamps not the cu! got to have access for tests etc, but just couldnt get one rcbo to hold even changed it to a mcb then it was tripping another rcbo??

 

[Guest123]

just couldnt get one rcbo to hold even changed it to a mcb then it was tripping another rcbo??

Ok.

Sounds now like you may have crossed ring conductors i.e outgoing ring 1 with incoming ring 2 and vice versa???

 

[Pete/2472]

Ok.

Sounds now like you may have crossed ring conductors i.e outgoing ring 1 with incoming ring 2 and vice versa???

yes thought that myself but after 12 hours work with a couple of hours trying to work out which leg went with which from the ring i had to call it a day! just thought there might be a easier way? ps
theres also about 4-5 radials mixed in for good luck..thanks

Ok.

Sounds now like you may have crossed ring conductors i.e outgoing ring 1 with incoming ring 2 and vice versa???

Thanks for your help Lenny, No crossed ring but found another sub board in a locked cleaners cupboard with a triped rcbo connected to one end of radial through the socket outlets and the other end connected to the other sub board (pryo) luckily both on L2 ..cheers for the tip.