when the fan initially 'kicks in' it's likely to be drawing more than 30a at that moment. i've always run a 40a fuse for any decent sized electric fan and not blown a fuse yet.
neil.
Cool. That was going to be my next attempt. The instructions that came with it said to use a 30, but it obviously isn't holding up so I'll try popping a 40 in before I head back home and see if it lives.