A customer asked if there is a difference between UK and North American fuses. Here’s my reply:
Absolutely! British fuses are rated by blow rate and North American by flow rate.
A 32 amp British fuse is designed to carry a current of 16 amps and will blow at 32. An American 32 amp fuse is designed to carry a current of 32 amps and won;t blow until it is substantially higher than that.
Fit a 32 amp American fuse to your British bike and if you get a short (quite common on BSA’s from my personal experience) you will be at best buying a new harness and at worst putting out a fire.