Voltage drop by wire size (60 A, 100 ft, 240 V)
| Copper wire | Drop (V) | Drop (%) | Within 3% |
|---|---|---|---|
| 6 AWG | 5.89 V | 2.46% | ✓ |
| 4 AWG | 3.70 V | 1.54% | ✓ |
| 3 AWG | 2.94 V | 1.23% | ✓ |
| 2 AWG | 2.33 V | 0.97% | ✓ |
| 1 AWG | 1.85 V | 0.77% | ✓ |
Voltage drop = 2 × 100 ft × 60 A × resistance ÷ 1000. Keeping it under 3% on branch circuits (5% total) is the NEC recommendation in the informational notes to 210.19 and 215.2.
Frequently asked questions
Is 6 AWG enough for 60 amps at 100 feet?
It carries 60 A, but at 100 ft the voltage drop is 2.5%, which is acceptable.
Does the distance include the return wire?
No. Enter the one-way distance; the formula already counts both conductors.