mcb trip why?

[debzo]

Hi - got one of those fancy ceiling lights that looks great but keeps tripping the MCB. It has 10 x 10w G4 lights with a 12v toroidal transformer. It is new fitting I've had in it's box about 1 year, but only recently put up after building works finished. I changed the fitting to normal pendant rose & everything o.k. So must be light fitting? - I want to test the fitting to find where the problem is as its past the guarantee time now and have been given a multimeter but am not sure how to test the transformer? If it is a duff one, can I replace the toroidal with same size electronic transformer or not? Haven't got enough money to call in electrician this close to Xmas and I would rather not have a bare bulb up for weeks on end!

Thanks.

 

[securespark]

Is it tripping on switch on or after a while?

 

[ban-all-sheds]

And is it definitely an MCB which is tripping, not an RCD or RCBO?

 

[debzo]

Is it tripping on switch on or after a while?

Thanks - It is tripping on switching mostly, have checked the switch wiring - all o.k - and it is now switching a normal pendant rose without a hitch.

Ban-all-sheds: It is definitely the MCB. It is on a split load dual RCD board, but only the MCB on this circuit trips.

I have been told the toroidal type transformers are the least problematic so am thinking it is maybe faulty?

 

[FDJ]

Probably just high inrush current which is a feature of toroidal transformers.
Either replace your MCB with a "Type C" or replace the toroidal transformer with electronic ones.
Frank

 

[debzo]

Probably just high inrush current which is a feature of toroidal transformers.
Either replace your MCB with a "Type C" or replace the toroidal transformer with electronic ones.
Frank

Thanks for the advice Frank - will try the transformer first and see if that resolves it.