Mike Clarke wrote:

Caecilius wrote:

A 13 amp fuse can take 20 amps for a long time before it fails.

I expect a cable rated for 13A would also survive for longer than it
would take for the 13A fuse to blow.

Apparently showers (Riba seem to be either 8.5, 9.5 or 10.5kW) can run
from a 13A FCU with some 1mm flex

https://youtu.be/AOZmgi8sdd8?t=121