The fuse or small bulb is only a temporary test to check that new wiring or circuits aren't short circuited, if there is a problem the fuse blows before the wiring is damaged. Once the inital checks are done the fuse MUST be removed and the battery cable connected normally before attempting to start the sngine. I guess I assumed you would know it's a temporary test and not a repair.
Maybe I didn't understand when your wiring burns out, is it only after you start the engine?
Clifton