Indesit KP59 cooker trips RCD.

Scooby · Jan 22, 2013

Hi all.

This is a 7-year old but barely used (10 times max?) dual-fuel cooker that has started tripping the RCD when the oven is used. This is an intermittent fault - the last time it was used, some months ago, it worked fine. The time before that it tripped the RCD after 10 minutes, and when I went to use it again a few days ago it tripped the RCD after around 5 minutes. When reset, it then truips the RCD either instantly or after a few seconds if allowed to cool a wee bit.

Ok, here's the thing - it trips the RCD on every oven combination setting - there's about 8 - except the 'defrost'. The 'defrost' is simply the oven fan spinning on its own to circulate the air. It trips on every other position even without the oven temp control being turned. It also trips regardless of whether it's the fan oven, grill, top or bottom (or any combination...) element being selected - and regardless of whether the oven temp control has been turned.

My suspicions, therefore, fell on the separate 'ventilation' fan (located in the back to keep the oven workings cool) which comes on with every selection except the 'defrost'. But it ain't that as I've just disconnected it...

It can't be the lamp as that comes on with everything.

I guess it could be the oven temp thermostat as this is brought in to play with - I think - every setting apart from 'defrost'. Could this 'leak'? It certainly seems to work fine - 'clicks' when it should and did give the correct temp.

There is an electronic clock/timer, but this seems to work fine as well - and anyways surely that would affect the 'defrost' setting too?

It can't be a specific element as it trips on every oven/grill setting - UNLESS the oven selector is double-pole and also connects all the element neutrals regardless of which one is being used? Can a neutral-to-earth fault trip the RCD? My house's earthing system is via an earth rod - does that matter?

HELP!!!! PLEASE!!!! IDEAS!! What should I try?

(Ok, I have a test meter wot has a 20M ohm range, so I'm about to see what the live-to-earth reading is for the whole oven, and ditto for neutral (tho' since the oven's been off for a while the fault might not show). And then I guess I should do the same for each element? Is there anything else? Any tricks/hints?!)

Thanks.

telectrix · Jan 22, 2013

if your test meter's a multimeter, it's no use. you need an insulation resistrance tester that will shove 500V up the oven.

Clive P · Jan 22, 2013

Hi,
In your post you mention N/E Tripping the RCD ( yes N/E will trip the RCD ), that would be my first port of call. You'll probably find all the Neutrals are tied together, you will need to do an IR test on all of the elements, you've probably got one with low IR to Earth,

Regards.

Scooby · Jan 22, 2013

Teletrix, I suspect you're right - I'm getting some seriously weird readings from my meter, including completely different readings - and a -ve symbol added - when I reverse the probes... Negative resistance - whooopeeee.

Clive, that's promising then - there's clearly a fault that's common to all the settings bar the one that just runs the oven fan. I notice that both the neutral and live supplies go to the selector switch, and a neutral leaves from the other side of the switch and daisy-chains to all the 'ancillaries' like fans and lamps. The cables to the elements are colour-coded, but it ain't clear to me which is L and which is N (orange, red, grey, brown, white...!)

Ok, I'm going for the process of elimination. I'll remove all the L & N from each element in turn.

Yes, I'll make sure they're 'safe'!

Thanks a lot, gents. I may need to call on my local 'appliance' man if nothing obvious jumps out at me.

Scooby · Jan 22, 2013

AAAAAAAAAAAAAAAAAAAAAAAAAARRRGGGHHH!!!!!!

Why do I have to complicate things?! Why do I have to think? Don't think. Thinking is bad.

If I had just read all the suggestions on the grand ol' internet - "it's elementary, dear twitson" - then I would have simply disconnected each element in turn and would have discovered the faulty barsteward in around 5 minutes.

And I wouldn't have taken half the day.

And I wouldn't have to repair the ripped-out terminal on the vent fan (why are spade connections so f'in' unpleasant?).

And I wouldn't have had to repair the two sheared bolts on the burner panel (as I tried to get access to the main selector switch...)

ANYONE COME TO THIS THREAD VIA A 'SEARCH' FOR A SIMILAR PROBLEM? Well, make sure you don't electrocute yourself, and just disconnect (and protect) each element's terminals in turn.

Once the oven stops trippin', guess what - you've found your fault.

It'll be an element. Almost certainly. Why? Well, why not - what else could it be? Of course it's the bludy element...

(And, if it isn't, then just disconnect every other foffing thing in turn. Job done

.)