But I have seen many consumer unit changes where 63A RCD's are fitted but it has a 100A incoming fuse. I blame electricians being lazy and since the consumer unit comes fitted with a 63A RCD they continue with that size.
Question now is...
A lot of the "off the shelf" CU's come with a 100A double pole MCB incommer and then proceed with 63A RCD's.
This, according to the logic in this thread would be dangerous as the RCD would be exposed to higher currents than 63A and even higher than 100A whilst waiting for it to trip due to overload.
Plastic melting, fire etc?