Who told you that? A fuse isn't going to regulate the current (until it blows completely). Fuseboxes shouldn't get hot, the fact that it fell out indicates it wasn't installed properly (which definitely can cause the heating).

Those Murray panels were not the highest quality. Two of the main causes of overheating are a failure to fully seat the pullout when putting it in place and the loosening of the wire terminals connecting to that main fuse block. After a serious overheating, the contact quality is seldom as good as original and additional problems can be expected. Smack the pullout with the heel of your hand to seat it. Tighten the wire terminals. If overheating continues, replace the panel.

Fuses can blow (melt the element) from overheating that is not related to a current overload.

This post was edited by bus_driver on Fri, Sep 6, 13 at 17:18

What would cause that to happen bus_driver?

Fuses can blow (melt the element) from overheating that is not related to a current overload.

If the fuse is not properly seated, arcing and sparking could occur which would create enough heat to desolder or melt the cartridge fuse element. You would also see other heat related damage to the fuse block which could cause it to need to be replaced.

Doesn't even need to arc, just a poorly made connection can cause significant heat especially on these high current fuses. There's good reason we require connections to be made in boxes.