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Cooker tripping RCD

Community Veteran
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Registered: 18-02-2013

Cooker tripping RCD

Got a new cooker 18 months ago Bosch HBN53R550B/46 which is tripping the RCD when the cooker is turned off.

Two things spring to mind, the lamp stopped working a while back and we didn't get around to replacing it untill last week, but in the mean time the RCD had been tripping every other time we turned the oven off which is a bit odd. Today the other half said that new lamp isn't working again. Luck has it we ordered two of the same lamps just incase, on trying the other new lamp it broke after about 60 seconds after turning the oven on, so as I grabbed it out to have a look at it the glass protector and the bulb was seriously hot even though the oven was on with thermostat set low, looking at both lamps again, it's almost as though they have burnt inside out for some reason, very black elements on both lamps.

Is this a short of some kind, or would there be a problem with the power selector playing up as well as the lamp holder?

Looking at spares for these types of cooker, the main spares look like lamp holders,lamps and selector switches.

 

No I am not fixing it myself, I am just curious.

 

 

 

37 REPLIES
Community Veteran
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Re: Cooker tripping RCD

Call in an electrician, could just be that you have a dodgy RCD that's tired and needs replacement as they do wear out with age, other reasons, well, who knows, could be anything, so, hire an electrician to find out... Smiley

Community Veteran
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Re: Cooker tripping RCD

The Electrician has been asked to pop round, so we wait, and wait........

Meanwhile we have called in Bosch, they are due in sometime next week.

But, that doesn't explain why 2 lamps of the correct rating and wattage and of good quality just blow for no reason.

Community Veteran
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Re: Cooker tripping RCD

You mean the oven lamp? Short circuit on the lamp holder? Current protection is high on an oven so it'll cook until it goes down to earth.

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Re: Cooker tripping RCD

@nozzer that makes sense, but.... I would expect If there is a short in the lamp holder causing the RCD to trip, why does it not do so when we turn it on is what I don't understand ?

It seems counter-intuitive that it only whacks the RCD when the oven is switched off, unless of course the short is more profound when the oven has been run full tilt to cook the dinner.

To note: A new lamp blew inside 60 secounds from the oven being switched on from cold, so there must be a short all the time within the lamp holder.

 

 

 

 

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Re: Cooker tripping RCD

A bulb would only blow if it was being over-driven, not if there was a short in the socket, if there were a short in the socket, the bulb wouldn't light up or would only light intermittently...

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Re: Cooker tripping RCD

Our dual fuel Rangemaster has two ovens, one is convection electric and the other is an electric fan oven. If we let too much moisture accumulate in the fan oven it will trip our mains RCD. The convection oven doesn't have that problem.

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Re: Cooker tripping RCD

@twocvbloke not sure how I would be overdriving a lamp rated @ 230/240 volts 25 watt 300°

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Re: Cooker tripping RCD

Neither do I, hence hiring an electrician to take a look... Smiley

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Re: Cooker tripping RCD

So how does a fuse blow then ?

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Re: Cooker tripping RCD

A poor electrical contact between the bulb and socket causing arcing and overheating of the bulb and breakdown of insulation resulting in the RCD trip.

A long shot though and professional assistance should reveal the problem.

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Re: Cooker tripping RCD


30FTTC06 wrote:

So how does a fuse blow then ?


 

Over-current usually, bad connections can overheat them and melt them too thus breaking the fuse wire...

 

Of course, if something is causing a fuse to blow, then it either has serious problems, or it's a PEBCAK and someone put a 3A fuse in a plug for a 13A rated device... Smiley

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Re: Cooker tripping RCD


Strat wrote:

A poor electrical contact between the bulb and socket causing arcing and overheating of the bulb and breakdown of insulation resulting in the RCD trip.

A long shot though and professional assistance should reveal the problem.


 

Thanks for the informed reply @Strat

@nozzer pointed to the same thing as well in short.

We are waiting for a sparky to turn up at his leisure, and the Cooker people are due in sometime next week.

I wanted the Electrician to have a look at the wiring with test equipment first seeing as he gave us a 10 year cert last last year, but as stated above it's as and when the guy is free. I guess if it's our side with insulation breakdown or even RCD etc we will have to pay a cost. Although I'm pretty sure the problem doesn't lie with us I can't be 100% sure, thats why I was trying to understand how A short in a lamp holder is causing the RCD to trip only when the appliance is turned off and also in a very random way as well as taking out three lamps in quick succession which didn't affect the RCD.

I understand that leakage can come from many places, in a lot of cases either a selector switch a thermostat, or even a hot spot on an element causing a short. I guess all of these can cause arching in a random way, guess I'll have to wait and see as the item is under warranty.

 

 

 

 

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Re: Cooker tripping RCD

If this is happening when the oven is being turned off it sounds like a dodgy simmerstat to me, it maybe worn and suffering from contact bounce and causing a short, hence the tripping of the RCD.

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Re: Cooker tripping RCD

Yes, the RCD only trips when turning the oven off.

I've not had it happen to me yet, it seems the other half has had it trip on her several times, but I am unsure in which order the problem is happening, IE is it when the stat is turned off or the power selector to the oven.

I have in my mind that more than one problem exists, so you could be on the money there @Mook