Elderly Smeg Dual Fuel Cooker Keeps Tripping Rcd

Johhny · Apr 8, 2014

Hi Folks,

I've recently acquired a SMEG SUK80MFX1 duel fuel cooker.

All the gas bits are fine, but as soon as the cooker is connected to the power its trip the main RCD.

I tried each of the (three) elements intern, by disconnecting them and trying the power with no change i.e still trips out.I then disconnected the main oven fan and tried aagian and LO! no trip.

All the other electrics seemed to be OK - lights, other fan, all three elements seems to warm up ok.

So , just to be on the safe side before ordering a replacement fan (they're kinda pricey) I pulled it and bench tested it. Now it gets odd - the thing worked just fine.

So im left scratching my head a bit, but have got this far with it: If the fan is OK then something else must be making it trip.

So could it be the thermostat/control knob?

If its faulty would it cause the whole thing to trip as soon as its connected to the mains even though the control itself hasn't been switched on?

Could it be the the thermostat probe, and again would it cause the symptoms Im getting?

Could it be one of the two TOCs? Ive tried both with a multimeter and the one to the fan did show a markedly lower reading (1.6 ohms against 4.1 for the other) but as this thing is supposed to cut power, why would it trip the RCD if faulty?

Is there something else Im overlooking entirely?

Very grateful for any insights or suggestions.

Cheers

Johnny

ProDave · Apr 8, 2014

If all you have done is remove the old fan and it stopped the tripping then it must be the fan.

The fan "works on the bench" but I'll bet you have not earthed the metal frame of the fan while on test have you?

Try earthing the metal frame and repeat your bench test. And make sure you ARE testing it on a socket protected by an RCD.

Johhny · Apr 8, 2014

Hi Dave.

Spot on - I didn't earth it on the bench, no.

But if its working ok otherwise, does it indicate something fixable in the motor or is it simply a goner?

Cheers

Johnny