Yet another Smeg oven tripping the RCD… C92DX

[Monkey Puzzle]

Hi folks, I really hope you can help me out…. My lockdown project was to pull the wall down between the dining room and kitchen and make the whole lot better… well, thats done but the Smeg oven I picked up has been a bit of trouble.. The first issue was that the flame safe device on the wok ring didn’t work. So i’ve replaced that and all was good but pretty swiftly the oven started to trip the RCD on the main DB. This was when using the fan ring on the main oven (pretty well all we use).

So: looking at the ring it didn’t look deformed but there was a section of it that didn’t glow red so I ordered a replacement. I’ve put this in and it still does it…. this is getting a little boring.

Any help would be really appreciated.

Matt..

[electrofix]

does it do it as soon as the oven starts or sometime when its warmed up

did you use a gen or copy element ?

Dave

[Monkey Puzzle]

Many thanks for the reply, it does it when it feels like it! I put the new one in, (its an original) it then popped the breaker and on inspection there was damage to the live wire going to the element which I think may have go to earth. This seems to have taken out the timer (I read 11v across it so took it out of the circuit with a ceramic terminal block). It all worked ok on a soak test up to about 200c so I put it all back together and slid it back into place.

Pasta bake is made and into the oven, it goes pop about 5 mins later while i’m up in the office and all the power goes off and its tripped the RCD again. I’m pretty sure that once its tripped, its not relevant what the selector switch is set to…. so I fire up the smaller oven and luckily the dish fits so the kids can eat…

After dinner I pull it all out again and fire it up with the back off to see how the elements meter out.. I leave it on soak for 45 mins and it keeps going with no issues, switch it between elements, wind it up to 220….. it’s all fine… So, I put it back together and with it live I do one more thing to see what happens. I move it back into place with it running. As you can imagine, there’s a bit of juddering with this process and guess what, It trips each time I gently slide/bump it into place…

[electrofix]

sounds like a wire is touching something it should not

Dave

[Monkey Puzzle]

Cheers, although thats probably the cheapest fix, its also one of the hardest to find as its so random! I’ll have a bit more of a dig later tomorrow and follow each cable through the unit and post back my findings.

[electrofix]

check things like the rear cover first in case it was knocked in transit

Dave

[Monkey Puzzle]

I haven’t taken the back off of it again but tried it out today. This morning I put it on the Fan element and left it for about 30 mins at 200*c and at some point it tripped the rcd so I flicked it back on and then all was fine. I switched the selector to Bottom Heater plus fan and it tripped straight away. I switched it back to the just the fan element and it was fine and then back to Bottom element plus fan (which had just tripped it) and it was fine. I’ve just left it on again at 220*c, for about 45 mins, switched various options, added in the other oven and I can’t make it trip…..

I have read that sometimes the fan itself can trip them. What are the symptoms of this? I did however measure a small voltage between Neutral and Earth when I had it on last night, about 0.5v i seem to recall at the screw terminals at the back, where could this be coming from? I get a reading of 0 ohms from the earth on the Distro Board to the metal of the case so it is properly earthed.

Time passes..

I’ve just gone back to it as I couldn’t send the first bit of this as it had just tripped and taken out the WiFi. I switched it off and then around the clock from off to lamp on to top and bottom elements and off it goes. I reset the RCD and do the same again and it doesn’t trip.

I just can’t get a repeatable scenario that trips it… grrrr…

Ah! unless its leaking 20ma to earth and something else in the house is kicking in, leaking 10ma+ and pushing it over the edge?

[electrofix]

“Ah! unless its leaking 20ma to earth and something else in the house is kicking in, leaking 10ma+ and pushing it over the edge?”

that can happen

from what your saying i am supecting the lower element

try disconnecting that element and see if all the rest works

also forget reading a voltage from neutral to earth thats normal to get small voltages

what you need to to is set your meter on a high resistance range ( at least 2M ohm) disconnect eact element and see if you get a reading to earth

also sometimes the earth leakage of an element increases with heat so it wont trip till it gets hot

Dave

[Monkey Puzzle]

Cheers Dave, I’ll check the lower element. It does seem to trip when set to just fan element though. I metered out the lower element when in that mode and nothing is sent to the lower element so its out of circuit unless it kicks in at some temps and not others… I’ll disconnect it, meter it, leave disconnected and make safe and use for a bit and report back…

Matt

[kaibart]

I think you will find that the is 1 wire that goes to grill element fan element and base element probably a neutral feed so it won’t matter what setting you select it will trop when it’s hot, if you don’t use the bottom element it is more than likely that but disconnecting like dave said you can rule 1 out at the time

[Author]

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