rcd trip y

[stodsy]

hi i was on a fuse board change to day and the new fuse board was switch off and no buzz bar connected and no tails connected but 1 of the circuits which was a radial to the kitchen when you put the neutral in it tripped the rcd can any 1 tell me why

 

[SPARTYKUS]

Radial was fed from another source?

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I've found T&E running between houses under patios....

 

[stodsy]

but there is no voltage on the cable but the job was 2 houses knock in to 1 but that was done years ago

 

[egg67]

Did you do any test before you wacked the new CU in, think anther post gives a good few steps to so before getting the new CU out of box

 

[guest119]

Radial was fed from another source?

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I've found T&E running between houses under patios....

Bet you never found Trevor jordash but.

Boydy

 

[HappyHippyDad]

but there is no voltage on the cable but the job was 2 houses knock in to 1 but that was done years ago

I hope others will correct me if I'm wrong but even if the circuit is not live (MCB open) the RCD can still trip if there is a neutral/earth fault.

 

[Selfmade]

As happyhippydad says, the RCD can trip with the circuit MCB off if there is a N-E fault, but the RCD must be energised from somewhere - try pressing the test button on a not-yet-fitted RCD - it won't trip. So there must be power coming from somewhere. Could the radial be getting it's live from the supply to what was the other house, and neutral from the one you are working from? (NOTHING would surprise me.) Then the circuit N would only have voltage if a) there was a load connected, and b) the circuit N was not connected to supply N or E.

Also, there must be something connected to the feed side of the RCD for there to be a path, and hence any current flowing through it.

 

[stevethesparks]

Could be induced emf coming up the T&E from somewhere?

 

[Deleted member 72666]

Bet you never found Trevor jordash but.

Boydy

Brookie, now that was a proper soap.......Unlike the crud that's on these days.Billy Corkhill and co brings back memories.