I have an old fuse box and have used the old 30amp cooker fuse to power my shower (30amp), however the shower I have purchased needs a 40amp fuse - can I change the 30 amp fuse wire and replace with 40 amp wire?

Thanks Danny

The next physical size fuse after 30 amps increases, so the 40 will not fit in the 30 amp fuse holder.

All of today's appliances really require a good distribution system, and circuit breaker panels of sufficient size for the total load help with preventing outages and fires.

If there is a way for the 40 amp to get connected to the fusebox, be sure to check the load on the mains that there is enough capacity.