We usually specify the maximum current that a conductor (such as a fuse) can handle without burning. But doesn't the conductor really fail when a certain amount of energy/heat has been dissipated in the conductor? Then the conductor is at a too high temperature and burns/melts.
Let's say I have a fuse that's rated for 10A. Why is it then that I can operate the fuse continuously at a lower current like 9A without the fuse burning too, but just a bit later?
We also know that power, voltage and current are related by Ohm's law. So if we have a 10A fuse, and it has some arbitrary resistance such as 100 ohms, why don't we instead call it 1kV fuse (10A * 100 ohms), or 10kW fuse (10A * 10A * 100 ohms)? These numbers are completely arbitrary so I know they don't reflect reality but they make my point clear.