Trip switch tripping on various circuits

[freddyuk]

I have had random tripping of my main trip 80a 30ma.
I now cannot get all the circuits on at the same time.
I can get any of the circuits to work so long as i don't have everything on together. ie. no one circuit throws up a fault.
Having checked and rechecked everything i have concluded that the actual trip may be the cause as i have over the years tripped it many times doing various work (and touching earth on dead circuits))
Today i tapped the main trip and it went off! I mean a gentle tap with a small screwdriver. Should that make it trip or is it indeed the switch that needs replacing.

 

[wingcoax]

A tap with a screwdriver should not make it trip. Possible faulty RCD.

 

[RF Lighting]

I wonder if it was right on the threshold of tripping, then a tap might just be enough to operate the trip mechanism?

 

[Taylortwocities]

So, you have just one RCD as the main switch for the whole house?