RCD "nuisance" tripping

[AnonymousImport]

I recently replace an incandescent light in my garage with a fluorescent. Now the RCD which controls all circuits on the consumer unit trips occasionally just as the fluorescent light is switched off. If the fitting were faulty I could understand this happening when the light is turned on but not as it is turned off.
Can anybody explain?
Peter

 

[Hamiltonandy]

Interesting problem. I have had this happen rarely on a circular bathroom light. As I see it the switch cuts off live. However may you have some stored charge in a capacitor depending on phase of voltage cycle. The only circuit available is the neutral and earth. Current returning by neutral is seen by RCD as an imbalance of live/neutral currents.
Solution would be to replace single pole switch with a double pole switch. If you are using a pull switch it would only mean moving from 5A switch to 16A DP and hopefully base plate would not need to change. Any residual charge should dissipate internally over time.
I am waiting for time to put a scope on line to test this out as it is not a priority job at moment!