Light tripping RCD

[sparkyspike]

Any ideas on this one?

Two kitchen lights, both with circular fluorescent lamps and wired to come on together, keep tripping the RCD when the lights are turned off. This seems to me to be a symptom specific to fluorescent fittings with coils.

The room is switched with two 2way switches and an intermediate. They are all 10AX switches. The RCD trip time is normal and doesn't trip at 15mS.

Would I be right in thinking that the RCD (not an RCBO by the way) is tripping due to the surge on the collapsing coil? Is this likely to be a fault with the light fittings?

Yes, they are customer-supplied and from Homebase

 

[luminaire]

Have you tried taking one of them out of the equation and seeing if it works? If it does try taking the other one out?

 

[VanSolo]

Fault between cpc and strapper? Nail through switch drop perhaps?

 

[sparkyspike]

Haven't been on site yet.

 

[RF Lighting]

Sounds like there could be a N>E fault on the RCD side somewhere which is just below the tripping threshold, and the spike pushes it just over.

It might even be something daft like a loose supply neutral.

 

[sparkyspike]

We'll find out on Monday. I'll do a PFC at the light and see what comes up. Hopefully a loose connection is at fault - finding a fault on a dodgy fitting could be more difficult! Thanks for the ideas.