Power source fuse size....
Since all things are relative....
Fuse size is very relative to ..power needs, length of circuit run, wire size and intended load. This dedicated circuit should be used for keeping the trailer batteries fully charged while in transit. Using a 30 amp fuse would be more than adequate. A fuse of 30 amps will power many electrical devices. Some RV tow vehicles are wired to operate the power tongue jack with this circuit. The jack is always operated with a full and ready battery of the tow vehicle.
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