Cooker hood tripping RCBO - head scratcher

[Midwest]

Blimey. What if OP switched off hood at socket, moved hood switch to fast, then turned socket back on. Would this negate the problem and prove you right Marconi?

 

[AndrewMgan1976]

Is the cooker hood fitted on a metal stud partition wall? Could be the fixing screw is through one of the studs and is causing a parallel earth

 

[marconi]

Midwest, yes, according to my reasoning that is my expectation. I think it is the electrical disturbance/transients caused by the action of switching the cooker hood control (whether up in speed or down) after the motor is run up that precipitates the RCD trip via the short leg of the ring final circuit. It may be though that the transients are of different strengths and forms depending on whether one steps up or down in speed. The only real test is to do it and to to connect up test equipment to analyse why.

All that said, I am conscious that these types of problem are nightmares for the busy electrician and wasteful in time and money. That is why I tried to offer a practical solution first - the filtered socket and maybe transient tolerant RCBO. Be interesting to know if one or other solved the problem.

Rob190's idea of connecting the hood 13A socket further around the ring ( - in the ring or as a spur) was the simplest and cheapest and thus best way to proceed. It could be easily trialled first too.

 

[Midwest]

We'll have to wait for Rob to get back to us. Can't think it might be something simple, but willing to listen to any explanation.

 

[Rob190]

Thanks guys for all your input - great resource here.

Big thanks to Marconi for his detailed explanation & solution - hager RCBO sorted it.

Very useful to know for the future.

Rob