Oven tripping circuit breaker

10 Apr 2011
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United Kingdom

My mother has a oven with a grill that she has never used in the 4 years she has owned the oven (Oven been working perfectly for past 4 yrs). A week ago she wanted to use the grill which resulted in the ground floor of the house filling with BBQ smelling smoke (Burning fat on the grill I assumed) followed by the RCD tripping so she gave up on the grill. Few days later she wanted to use the normal fan assisted oven part of it which went fine for a few minutes before tripping the RCD again. Someone came out to look at the oven and she told me the person used some "prongs" on it which I assumed to be a multimeter and could not find anything wrong with it but suggested she try the pyrolytic cleaning function on the oven as she had never gave it a proper clean with it. On the pyrolytic cleaning function is ran for about 2 mins before tripping the RCD again. On a second attempt it successfuly ran the 1 and a half hour pyrolytic cleaning cycle.

However, yesterday she attempted to cook something in the oven but as soon as she turned the oven on (i.e turned it to the fan assisted oven setting - not even adjusting the temp. of oven) - she said she saw a blue flash inside the oven and it tripped the 32A (230V) circuit breaker for the sockets and I told her to unplug it and not to use it until it can be checked out again as electrical arcing can hardly be good now, can it?

I'm not an electrician so I've assumed the following:

The MK 5932s is a 32amp 230v circuit breaker (Which has only tripped the once - with the blue flash)
The MK 5780 is a RCD (Rated for 80A with a 30mA sensitivity)

While concerned, I was not too worried about the RCD tripping as I know ovens leak quite a bit but I'm quite concerned about the circuit breaker tripping.
Is the oven safe to use and why did the person who came out to check it last time not find any fault with it?

Thanks :)
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There's an insulation breakdown here, either in the wiring to the element or the element itself....the oven needs to be professionally repaired and tested.
In days gone by this could have resulted in fire, but because our RCCB's and other circuit breakers are so good, we remain safe.
John :)
it's common for the insulation in oven elements to break down over time, with age or damp, and fitting a new element is usually the easy fix. However this fault usually causes the RCD to trip, with no flashbang from the oven.

If you got a flashbang after someone had been poking about at it, he might not have seated the element plug firmly into its socket or something. On my Zanussi the element has a 3-pin heat-resistant plug on the end. Or maybe a wire got trapped (though this should be difficult to do)

The pyrolitic clean will have got it very hot and probably dried out any moisture in the element insulation which typically causes the RCD trip..
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Tomerf; You didn't mention the make/model of the oven....it is always an advantage & it help us to help you.

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