Help Needed with Strange Appliance RCD Tripping

[zion]

Hi,

We've had an ongoing problem with our oven in that when we use the main fan oven part, one of the RCDs in the consumer unit will trip. However, after having the element replaced, we've found that a few weeks later it is still happening. I know its something to do with the oven because it happens sometimes when the oven temp relay switches in. It could be the fan I guess, but I'm not so sure .... (see below)

Weirdly, I noticed that it doesn't trip the Oven RCD, it is the main RCD for all sockets and appliances in the house that trips. When that happends the Oven RCD doesn't trip out - and I've confirmed that manually turning this RCD off does indeed turn the oven off.

So is there something else going on here? Is the oven maybe not at fault? Why is the main RCD tripping but the oven one isnt? Is it because the level of residual current on the main ring is too high and the oven is just pushing it over the edge?

Is there a way I can check the level of residual current flowing around?

Please help us! We're fed up with cold food

Z.

Main RCD - Crabtree RCCB SPLIT-LOAD 63A 30ma, 363/S030
Oven RCD - Crabtree MCB B32 61/B32

 

[JohnW2]

Weirdly, I noticed that it doesn't trip the Oven RCD, it is the main RCD for all sockets and appliances in the house that trips. When that happends the Oven RCD doesn't trip out - and I've confirmed that manually turning this RCD off does indeed turn the oven off.

That's not weird, but you've got the terminology wrong, and probably don't fully appreciate the difference between the two devices. The (B32) device for the oven is an MCB (Minature Circuit Breaker) and that would only trip if the oven took an excessive current (appreciably over 32A) - which isn't happening.

What you describe as the 'main RCD' (63A 30mA) really is an RCD (Residual Current Device) and that will trip if there is a fault in the oven resulting in a leakage of electricity to earth - so that's the problem you have. Elements are the most common culprit, but if you've replaced yours (without curing the problem) that's probably not the cause (although new ones have been known to be faulty). Are there any other elements? Whatever, you have a fault in your oven.

Kind Regards, John

 

[zion]

Thanks John - that's really helpful.

Yes, there are several others elements (eg ones in the other side of the oven). Could these be leaking to earth even when not in use?

Thanks

Z

 

[JohnW2]

Thanks John - that's really helpful. Yes, there are several others elements (eg ones in the other side of the oven). Could these be leaking to earth even when not in use?

It's not impossible (switching probably only disconnects one side of the element, leaving the other connected) - I fear you're probably going to need an electrician to try to sort it out. It would be daft going around changing everything 'just in case'.

Kind Regards, John