Problem with oven

Ask the people who supplied the oven to check it over. It is unlikely to be a circuit fault. However, trust me they will insist that it is after they have checked it.

 

It will probably be the element.

I've had them before where the element fails IR only when very hot and only for a few seconds after the power is cut. You can megger it real quick after you cut the power.

If it's a new oven just send it back though. An electrician doing IR test and Zs being good on the circuit is, I think, enough work to eliminate reasonable likelihood that the problem is with anything other than the appliance, so it's not your problem.

 

Strange it's on a new oven, but perhaps it was stored longish term in a cold damp warehouse?

I had this exact problem with our oven, one that wasn't used for a few years after it being installed - used occasionally at Christmas!

I couldn't isolate the area of the problem since every oven setting tripped the RCD after a minute or so - grill, conventional, fan etc.

I'd actually taken the bludy thing apart, blaming the cooling fan - as the only item common to everything else - when either this forum or another one on t'net pointed me to the likely cause - damp in an element.

And the reason why it tripped on any oven setting was because it was leaking via the common neutral connection...

Removed the back of t'oven and disconnect all the elements, reconnecting them one at a time. Bingo - it was the inner grill element.

 

You get weird effects sometimes. One I had in th past occasionally tripped the RCD at the instant you turned the oven off when you had been cooking - not any other time.

Turns out that there was a crack in the element which was causing leakage. The rotary switch was dual pole and actually isolated neutral milliseconds before phase was disconnected. And at that instant that neutral was disconnected the whole element comes up to line level, and consequently the leakage current brought the element increased - enough to take it over 30mA.