The fuse indicator just serves as, well… you guessed it: a fuse indicator… Its main purpose is to show the dumb electrician that he just blew up a fuse. (including myself here…)
It really just is a LED with a series resistor. And in order to prevent the AC voltages from destroying the LEDs, I used diodes to create something like a half-wave rectification.
And that’s it. I think schematic is not necessary here… 😉
And some pictures: