I've just replaced an RCD which had failed. It was 63a 2-pole, between the meter and the main distribution board, in its own box. The only one I could get was 80a, but I can't see any problem with that? Both 30 ma.
I tightened the terminals and checked for heating up with everything switched on.
What have I missed?
BTW, I had to pull the main fuse - the one with the electricity company seals. Is that a big problem? Well, I didn't have to, but I thought it was a good idea....