Voltage Drop Calculator | PES Supply
Quick answer
Voltage drop: single-phase VD = 2 × K × I × L / CM. Keep branch circuits ≤3% and feeders ≤5% (NEC 210.19). #12 copper at 20A drops 3.9% at 100 ft. Calculator below.
Voltage Drop Calculator
Calculate voltage drop and wire size for any circuit
Wire Resistance (Ohms per 1000 ft, Copper)
| AWG | Resistance (Ω/1000ft) | Ampacity (75°C) | Max Distance @3% (30A, 240V) |
|---|---|---|---|
| 14 AWG | 2.525 | 20A | 47 ft |
| 12 AWG | 1.588 | 25A | 75 ft |
| 10 AWG | 0.999 | 35A | 119 ft |
| 8 AWG | 0.628 | 50A | 189 ft |
| 6 AWG | 0.395 | 65A | 301 ft |
| 4 AWG | 0.249 | 85A | 477 ft |
| 2 AWG | 0.156 | 115A | 762 ft |