View Full Version : amp loads and wire size

02-14-2007, 08:32 PM
What size wire is needed with a 55 amp or a 35 amp alternator? I switching from 6 volt to 12 volt, the wire runs from alternator to amp meter to solenoid. What amp load can the OEM harness of a 6 volt wire carry from a 12 volt alternator.

02-14-2007, 09:23 PM
I have a 35 amp alternator (mid 60's Mopar) and a 50 amp . I do not need the 50 amp one, just curious. Thanks for the reply.

02-14-2007, 10:12 PM
#8 gage wire will safely carry 35 amps, #6 good for 50+ amps, The voltage isn't the criteria.
It is the current and wire resitance that is referred to as I2R loss. This is the current squared multiplied by the wire resistance. The resistance is dependent on material (copper, aluminim etc.),length, number of strands and wire crossection. For copper, 1600 ft. of #8 wire has about one ohm of DC resistance. Now you will probably not have more than 16 feet of run so about .01 ohms. Heat=watts so at 35 amps squared x.01=12 watts. Not a problem to dissapate. I'm curious as to what on your car would need so much power. Twelve volts multiplied by 50 amps is 600 watts. Most headlights are happy at half that number and
usually are the prime watts eaters. maybe a zillion watt car sterao amp? <G>.

1950 Champion Starlight
1963 Hawk GT
Santa Barbara