On Wednesday, 13 September 2017 11:25:28 UTC+1, Andrew wrote:

Maybe a tree fell across the overhead low voltage phases nearby and
you got a momentary 480 volts.

It wasn't windy. If there'd been a storm going when the RCD tripped in the first place we'd have noted that as a cause.

In any case, I'd be amazed if the only damage caused by a voltage spike was to the dishwasher pump!