RCD tripping in newly installed CCU in garage..Help!

timmy123 · Jun 28, 2010

I have just finished installing apower and lighting into a detached garage some 15 meters from the customers house.. I have supplied the ccu in the garage via SWA cable. The garage ccu has a 30ma rcd. The supply from the house ccu to the garage ccu is via an mcb protected by a 30ma rcd.
insulation tests and continuity tests indicate no issues with cables however the garage ccu rcd trips everytime any load is connected to the sockets (on a small ring main) or the garage lamp switch is closed. The house ccu rcd is not tripping. I have a feeling that there may be an issue with discrimination on rcds but I am not clear on this area.
I would really appreciate some advice on this issue as the customer is unhappy and is talking about getting another electrician in to sort the problem.

Your help would be greatly appreciated.

Thanks

Timmy 123

Wardy35 · Jul 4, 2010

Just want to offer a suggestion as i did this when i did my first workshop, did you remove the temporary link cable after you did your continuity test, it may explain why it keeps tripping. Please dont take this suggestion the wrong way i am not trying to insult your intelligence.

I know you probably wont want to admit it if it is but it would be nice to know lol.

Regards
Mick Ward

mccant · Jul 4, 2010

have you donne all your tests and is polarity correct , rcds in series are not the reason this is tripping if its the garage rcd thats tripping , make sure all cpcs are together, is the garage a conductive material,concentrate on getting one circuit working like the light if this is testing sound you know that is not causing the problem i think you have the n/e crossed somewhere