Dale where the heck have you been ? There is different sizes that the factory uses. Basically the fuse link is a smaller piece of wire then the circuit is so it will burn out first in case of a short before the larger wire in the rest of the circuit. I have never seen exact #'s on the amout of amps it takes to burn them out. But I would guess that a 20 gauge fuse link will only take about 30 amps. The heater circuit uses a larger one like 16 or 14 gauge as they can draw 25 amps on high speed so I would think about 40 or a tad more amps would burn it out. Course when you get a dead short it will pump alot of amps thru it and burn out real fast. Ron