How many amps can 3 AWG wire carry?

Three AWG copper carries 100 amps at the 75C rating that most terminations allow, which makes it the textbook conductor for a 100 amp feeder. Aluminum 3 AWG carries 75 amps.

The full copper column: 85 at 60C, 100 at 75, 110 at 90, with the 90C figure usable only for derating math since ordinary lugs stop at 75.

For a 100 amp dwelling service specifically, Table 310.12 permits one size smaller, 4 AWG copper, under the 83 percent rule; that allowance belongs to whole-dwelling services and feeders only.

Odd-numbered sizes like 3 AWG are real but stocked thinly, so quotes often come back with 2 AWG instead; oversizing is always legal.

The amp wire size calculator maps any current to its copper and aluminum sizes.