Rural USA. We just had a gas furnace installed. The new furnace has a 1-gang junction box with a switch and a fuse.
It's the 21st century, here, I swear. And not England.
The furnace circuit is tip-top. It's punched down into a modern service panel with perfectly typical 15A breaker, and if it needed something special, that really wouldn't be a problem.
So why does the furnace also need a fuse?