Originally Posted by rebel heart
Can someone explain to me how a 4 gauge wire is supposed to transfer 30,000 amps?
Time and mass!
Thermodynamics are a set of much slower physical processes then electrical
conduction. Thus, if the electrical
conductor has sufficient mass and the electrical current
stops flowing soon enough to allow it to start cooling
before its temperature can rise to the melting point, it will survive.
A good example is the common fuse. This is a device that is designed to fail when excess current
passes through it. Yet it will survive short bursts of current above it rated value.
Another example is the incandescent lamp. A device designed to balance the thermodynamics and current flow to be very hot and not melt. And, when you switch off the current flow to the lamp, you can watch the much slower thermodynamics in action as its element slowly dims.