Interested to know what usually causes the breaker to trip?

Is it common to get an amp draw intermittently higher than breaker rating from components that does not really justify increasing wire size & breaker rating?

Up until this corrosion incident fuses have worked for me, But have always used fuses & wire size much higher than component requirement, that way if a fuse blew, there was a substantial fault somewhere that caused it. btw. only time a fuse has blown is on the ground when some idiot stuck a screwdiver where it shouldn't go. but then I haven't flown much either to say it wont happen in the air.

Andrew