I just learned something else. (Thanks to Ching’s A Visual Dictionary of Architecture and not to paying attention in class or doing the study guide or anything)
Did you know that FUSES are “a device containing a strip of fusible metal that melts under the heat produced by excess current, thereby interrupting the circuit”? So basically, a fuse is a safety switch. These days we have breakers which do the same thing—act as a safety switch, flipping off when too much voltage runs through—they just are reusable unlike the fuses that had to be replaced.
Now, that grounded wire. I get what it DOES and why, I just don’t get HOW it does it.