[matthewhouse]

There are some which indicate whether they have tripped or have been just been switched off by a coloured indicator. I think the ones we use show white for off and red for tripped. That mid position on the MK ones causes all sorts of confusion for the elderly. I'm on call for electrical problems. When asked if all the switches are in the on position they always say yes, on visiting it's obvious that it's in the mid position, especially when compared to the second one fitted in 17th edition boards. Not such a useful feature if your eyes are failing.

I would be carrying out insulation tests on the wiring and appliances next. Don't forget to test all the circuits protected by the RCD as a neutral to earth fault on a lighting circuit may not trip the RCD until current is drawn, from the cooker for example. It's probably something simple like a failing cooker element though, but only an insulation test will show this. Don't forget to test when the elements are hot too.