Plus a fuse won't protect against the wrong voltage.
Fuses are certainly not intended to protect against the wrong voltage, and they do only react to overcurrent, but they are still [supposed to be] designed to be the weakest link in a circuit. Otherwise you'd be using a circuit breaker and not a fuse.
In the example of most modern electronics, where line voltage goes through a switching power supply to low voltage circuit boards, the power supply will have a capacitor and fuse fed by line voltage. Doubling the voltage input will double the inrush current to charge the cap, making it likely that the fuse will blow. If you're lucky (and as I pointed out above, most solid state electronics handle pulsed power rather well), nothing else will fail. If not, then just the power supply (usually a cheap part) will take the brunt of the damage, with the easily fuse stopping it before it takes out everything downstream.
beat me to it.
Ive never seen a fuse, especially glass fuses, rated for the nameplate voltage. typically they are rated for a lot higher voltage and only purpose is for overcurrent protection.
I don't need to tell you, but just for other people reading this, the voltage rating on a fuse has just about nothing to do with stopping voltage. Fuses should be rated for the highest voltage they may encounter, since using too low a rated fuse could lead to internal arcing (i.e. failure to open when intended).
