RCD FCU randomly Trips ??

[TPES]

Had a call out today to a bathroom fault.

The bathroom has had a new light fitting and extractor fan, the electrician who had previously done the work had fitted a 30ma RCD FCU Above the bathroom door. since this has been done the tenants have said the rcd trips when they put the bathroom light on..
When i got there the tenant tried to make the rcd trip, he was pulling the light on and off and couldnt get it to trip.. then he put the fan on aswell and tried pulling the light on and off with the fan running probably 9 out of 10 times it didnt trip, and on the 10th pull it triped..

This seems to be an intermitant fault and only occasionly trips the rcd... if checked all terminations, nothing traped or caught..

35w fan
2D low energy light fitting (28w)

3a fuse in RCD FCU
3a fuse in FCU for extractor..

Any ideas?

 

[ghost]

The 2D ballast may have a little leakage, it may have a capacitor causing leakage. Likewise with the fan. I don't supose pulling the light switch on and off constantly would help either!!
This is one of those faults that could have you scratching your head all day.

 

[TPES]

There is a capacitor across the SL and N, Could this be at fault do you think, its a brand new fitting... I'm thinking its unlikely..

Not sure what to try?

 

[ghost]

The chances of the problem being the capacitor are slim to none, it's probably a plastic cased capacitor straight across live and neutral, obviously no connection to earth, therefore no chance of tripping an rcd.
I would suspect a ballast giving problems, try disconnecting the ballast and meggering the coil down to the case, if the insulation of the coil is suspect then this may show up under a high voltage insulation test.
As I said, it's going to be one of THOSE faults, nowt worse than an intermitent fault.

 

[Had8Lives]

Would suggest fitting a seperate RCD Spur for the fan until you resolve the fault. It may be the combinaton of inductive loads.

Just another thought. Ramp Test the RCD spur and see what current it trips at.

 

[TPES]

The tenant of the house has told me that a previous electrical firm have been out to try and resolve the issue, They had replaced the RCD FCU Twice, both times being the BG brand.

I have now changed the RCD FCU for the greenbrook brand.. the customer has been happy now for the past couple of days as it has not tripped once. (when it was previously tripping a few times per day)

Ive heard of other sparks having trouble with RCD FCU's other than the greenbrook. I cant see how.. But ill always stick to the greenbrook brand from now on if needed.