Zanussi oven tripping the RCD, Help im living on Pizza

[Christopher Middleton]

Hiya, I have a 5yrs old Zanussi single built in fan oven. It has recently started tripping the RCD at the fuse box. Thinking and researching i decided to replace the main element which i have done. The oven works for about 15 mins the fan comes on after a couple of minutes and seems to be working fine. Im guessing when it reaches a higher temperature about 10-15 mins it trips the RCD. Is it worth replacing the thermostat or should i just replace the oven. Im guessing a trip to a local repairer to diagnose the fault would probably cost as much as a new cheaper oven. Any help would be very much appreciated as im stuck eating Pizzas that cook at lower temps. Many thanks for any anticipated help.

 

[Rockingit]

Given that you can get a new single replacement of reasonable quality for under £200 you may decide that further diagnosis just isn't cost effective.

That said, what makes you think that the fault is the oven and not the supply to it?

 

[Marvo]

Unlikely to be the thermostat, far more likely to be one of the elements. Any half decent domestic electrician should be able to test the circuit and at least localise the fault to a component if it's an internal oven problem. I'd suggest that might be the best rout to go because if, as Rockingit implies above, it's a fault on the supply circuit then you don't want to spend money on a new oven only to still be sitting with the same tripping fault.

 

[Christopher Middleton]

Given that you can get a new single replacement of reasonable quality for under £200 you may decide that further diagnosis just isn't cost effective.

That said, what makes you think that the fault is the oven and not the supply to it?

im guessing as its been ok for 5+ years, the potential cause is probably a worn out part rather than a supply fault, but, im no genius

 

[Christopher Middleton]

Unlikely to be the thermostat, far more likely to be one of the elements. Any half decent domestic electrician should be able to test the circuit and at least localise the fault to a component if it's an internal oven problem. I'd suggest that might be the best rout to go because if, as Rockingit implies above, it's a fault on the supply circuit then you don't want to spend money on a new oven only to still be sitting with the same tripping fault.

thanks marvo thats a great suggestion and im reconsidering right now, thanks mate

 

[Avo Mk8]

If it's not a fixed wiring problem, I'll hazard a guess that the RCD may be tripping due to a leakage current that builds up as the oven heats.
Since you were happy to change the element, there are a couple of other things you might try:
Try removing the oven bulb (if there is one), or preferably the wires to it and temporarily insulating them.
And if that doesn't change things, disconnect both ends of the grill element (assuming you have one) and insulate them.
or if there's a supressor capacitor there somewhere (unlikely?), try disconnecting that!
I'm just suggesting temporarily disconnecting components (safely) to see if the tripping stops.

And re-reading the post - are you saying the oven fan only comes on a while after you switch the oven on. Surely that is not usual? Is it behaving as it always did?
Or do you mean the ventilation fan for the enclosure, which will only come on after a while. A fan could be a culprit - but I don't recommend running the oven element without its related fan running!

 

[Christopher Middleton]

If it's not a fixed wiring problem, I'll hazard a guess that the RCD may be tripping due to a leakage current that builds up as the oven heats.
Since you were happy to change the element, there are a couple of other things you might try:
Try removing the oven bulb (if there is one), or preferably the wires to it and temporarily insulating them.
And if that doesn't change things, disconnect both ends of the grill element (assuming you have one) and insulate them.
or if there's a supressor capacitor there somewhere (unlikely?), try disconnecting that!
I'm just suggesting temporarily disconnecting components (safely) to see if the tripping stops.

And re-reading the post - are you saying the oven fan only comes on a while after you switch the oven on. Surely that is not usual? Is it behaving as it always did?
Or do you mean the ventilation fan for the enclosure, which will only come on after a while. A fan could be a culprit - but I don't recommend running the oven element without its related fan running!

Many thanks for this Avo i can try some of these suggestions, before maybe calling in an electrician to do a diagnosis if I cannot find the fault. I would not know what a supressor capacitor is and the fan is the ventilation fan inside the oven. Many thanks Avo

 

[brianmoooore]

New element could be faulty. Used to keep a selection of elements on the shelf, back in the day, when RCDs were a 'new' thing, since it was very common to find nuisance tripping caused by a faulty one after fitting a new CU incorporating RCDs.
On a few occasions a new element was found to be faulty when it had been on a while. If you were very quick after the RCD tripped, and got the megger connected right away, you would just catch a L - E resistance of a few kiloohms, decaying in seconds to infinity.
There's also the other problem, not yet mentioned in this thread, of new elements absorbing moisture when in storage, and tripping an RCD as the moisture is driven out when heating.

 

[Avo Mk8]

That is a very good point from brianmoooore!
I'd forgotten about that effect of the element absorbing a bit of moisture.
Christopher - before doing anything else, you might try running the oven until it trips, letting it cool a bit and then repeating.
If it will stay on for progressively longer periods it MAY just be due to you putting in the new element which, at the moment, is a bit leaky!
On the other hand, if it trips ever more frequently, perhaps it's faulty?

 

[Christopher Middleton]

That is a very good point from brianmoooore!
I'd forgotten about that effect of the element absorbing a bit of moisture.
Christopher - before doing anything else, you might try running the oven until it trips, letting it cool a bit and then repeating.
If it will stay on for progressively longer periods it MAY just be due to you putting in the new element which, at the moment, is a bit leaky!
On the other hand, if it trips ever more frequently, perhaps it's faulty?

thanks for all this help guys i will come back when i get it sorted, many many thanks