When it does trip, it's the main RCD which goes; however sometimes an individual MCB flips as well. I hadn't particularly noticed which one, but I this morning I spotted that it was the main ringmain for all sockets in the house *other* than the kitchen! (the oven has a dedicated radial, and the kitchen sockets - including microwave - are on another MCB).
First question - do the above observations add up at all? The MCB thing makes no sense to me at all; I wonder if today's observation was just a one-off oddity today?
The first time this happened I thought (well, assumed, as I'd experienced this before) the problem was a duff element in the oven and just ordered a new one; when it arrived though (during which time there'd been no more trips) I checked the old and new with a multimeter, found identical resistance across terminals (20 ohms IIRC) and to earth (open circuit) and decided I'd been wrong, so returned the new element unused. Now wondering if I was incorrect in doing so. Could there be undetected earth leakage (which I don't have kit to detect? Could it be somewhere else in the oven? Or the house wiring? Oven is a built-in one about 10 years old; main element was replaced about 9 months ago.
Right now I'm really confused - I don't know whether I should be looking at appliances (which!?) or wiring. I'd happily buy a new bloody oven if that would definitely solve it, but I am concerned it might not!
Problem's really made worse by being intermittent, and because it seems to involve appliances we really can't do without.
Any advice on how to proceed most welcome!