Jim x321x wrote:

it seems likely to me that more accidents are likely to be caused by
a house's power being unexpectedly cut off due to a RCD misdiagnosing
a fault - especially at night. Elderly an infirm people suddenly
finding themselves walking around in pitch darkness, having to fumble
their way to the CU.

Hence newer installations having at least two RCDs with circuits split
between them, or RCBOs per circuit, so that faults on one circuit affect
fewer (or no) other circuits ... rather than being in pitch darkness you
could get a bit of light from upstairs reaching downstairs, or use
floor/table lights instead of ceiling lights etc.