Why would it be dangerous to replace the fuse in a plug with a piece of copper wire?
Fuse wire is just tinned copper wire. It is tinned for reasons of avoiding corrosion. Bare copper wire quickly develops an Oxide coating. Tinned copper wire does too, but it takes longer. If you had clean copper wire of the same diameter, it would be exactly the same as using fuse wire. Replacing it with a larger diameter copper wire would, of course, be dangerous as would using a larger diameter fuse wire of the tinned copper variety.
