Siemens oven tripping RCD

The grill element has an internal short and needs replacing. Sometimes you can see it as a slight bulging of the element. This happens just before it blows a hole. It may also have been physically damaged when something was put in there after a few Sherries. :>D Sounds like your RCD is adequately sensitive.

An RCD tripping points to an earth leak because that is what they are designed to do.
Check the wiring and pay special attention to the insulation.

yes
an accredited electrician can test the circuits for insulation failure , vermin shorting across active / neutral/ earth points and the rcd itself
it is not a diy job

The elements in ovens consist of an outer earthed metal tube and an inner resistive element that is insulated from the outer tube by what is effectively a compressed ceramic insulating powder. If the element is not used for a while, enough atmospheric moisture, (or from spills, etc), can penetrate the insulation to cause enough earth leakage to trip the RCD. If the RCD is tripping at the correct level, (They can get too sensitive - see this article here:
Diagnosing RCD earth leakage breaker nuisance trips), then the only long term solution is to replace the element, although they can sometimes be dried out by heating them.

door switch must be introducing a fault.
Why is a "fixed cooking equipment" on an RCD?

your heater elerment has gone in the main oven i had the same problem if you need help takeing it out and see if its the problem get back to me ok

If you are sure there is 220v going to unit, it most likely is element or click / control. If you have a ohms meter, you can test the element

I have a u1421 with the same problem! I notice the fan doesnt run too well, sometimes it doesnt run at all, needs a prod to get it running. I suspect with no fan, that the element gets far too hot, and then starts to leak to earth, tripping the RCD. I'm gonna try buying a new fan motor - you should ckeck if your fan is running full speed OK.

The main oven element has failed, you need to fit a new element.
If you remove the rear cover in the oven , you will see the element.
Disconnect and replace. Be care ful not to lose the wires behind the aperture.
Plz rate my solution.
Thanks.

I suspect not the oven element at fault. you only way forward is to actually test the resistance of the element to earth with a megga if you can beg the use of one. be cautious about the result as on occasion, elements are only faulty to earth when hot. another way to test if you are cdarefull, is to connect the element to mains independently of the oven and see if the rcd trips