[soundman98]

fuses are a limiting device. think of it like a cop with a radar gun. if the speed limit is 15mph, there is nothing limiting you from going any speed from 0-15mph, but anything over that limit, the cop/fuse will put a stop to the 'fun'.

typically, one should fuse a device for just over what it needs. this is done so that there is an allowable margin of error in power draw(if it draws a little more than it's supposed to, NBD), but if something goes wrong and the device starts drawing significantly more power, the fuse is there to stop it before the device can start on fire and cause more significant problems.