Fuses are rated to protect the size of wire that's being used. If the 14 amp fuse is correct, that's intended for approximately a #12 wire. You would need to measure the current draw of the motor in question, and add about a 50% overload capacity to the fuse, then use the right size wire to carry the current draw. The whole concept of a fuse is to interrupt the circuit before the wire can overheat to the point of damage. For instance, a 20 amp fuse on a #18 wire would allow a current flow sufficient to melt the insulation before the fuse would fail. A #18 wire works best with about a 7.5 amp fuse, maybe 10 amps max. As the accessory load and the wire size increases, the fuse size goes up to match it.
Edit: Dirty switch contacts or loose connections can result in localized overheating and damage, even if the wire and fuse size is correct.
Jerry
Last edited by Hotrod Lincoln; 11/23/2011 5:53 PM.
