Yesterday evening the built-in oven started behaving a bit oddly. It switched (unnoticed) from its normal convection setting to grill, and incinerated the fish fingers which it was supposed to be cooking-not-grilling. And it cranked the temperature right up to way above the range of normal grilling. It was as if it was ovening and grilling at the same time, and doing so under its own control. It was switched off on the normal oven controls and that worked for slightly less than 0.5 of a second which is when it switched itself back on and resumed ovening and grilling once more. Summoned to deal with the newly-independently-minded tech, I switched it off at the wall isolation switch and watched it not switch off. Slightly scary. So I went to the MCB and isolated the 3kw oven circuit which had no effect at all; the device kept on ovening and grilling. So then I went through all the MCB circuits; 2 switched it off. An RCD circuit and the household 13amp circuit. Marvellous, obviously.
When it had cooled enough, the oven was released from the built-in cupboard fastenings and withdrawn like some weird kind of latter-day Arthurian Sword In The Stone (oven in the kitchen cupboard?) and the second problem was identified first. Behind the oven was a standard household 13amp socket into which the oven was plugged. I pulled the plug, put the 13amp circuit back into play and while everything booted up around us, a swift decision on the oven’s fate was taken. Anyway, the oven is now on the drive awaiting the scrap-person’s attention. The new one will be delivered on Sunday.
That’s a hell of a story to concoct, just to explain why you burnt the fish fingers!
On a serious note, I hope (but I’m sure) the new oven will be wired correctly into that isolation switch.