What Edison discovered (and it was promptly dubbed the "Edison effect") was that electrical current doesn't need a wire to move through ... until Lee De Forest came along a decade later.

The fuse contains a thin wire that will melt if the current gets too high. If there is a fault that causes the casing of the device to become live, a large current will flow through the low ...

Live wire Copper wire coated with brown plastic along which the current enters the device. Fuse A glass or ceramic canister containing a thin wire that melts if the current gets too high.