The main RCD in our consumer unit seems to be very much on a 'hair trigger'
and cuts out regularly, causing mayhem to pc users and dvd recorders!

We thought at first it was just when the heater in the washer/drier kicked
in, but closer observation shows that it trips in various combinations of
heating element devices like kettle/toaster/cooker/washer, tending most to
cut out if two of these happen to be on at once.

Also light circuit RCD always trips when a light bulb goes, but main also
trips if the light's earth is touched when removing lamp holders even when
the lighting RCD is 'off'?

The consumer unit was fitted by a competent electrician and the problem was
not immediately apparent after the fitting.

Do the RCDs wear out?
How can they be tested?

Cheers for any tips,

S