Voltage Drop Chart by Wire Size & Distance
Voltage Drop Chart: 120V, 20A Circuit (Copper)
| Distance (ft) | 14 AWG | 12 AWG | 10 AWG | 8 AWG |
|---|---|---|---|---|
| 25 | 1.3% ✓ | 0.8% ✓ | 0.5% ✓ | 0.3% ✓ |
| 50 | 2.5% ✓ | 1.7% ✓ | 1.0% ✓ | 0.6% ✓ |
| 75 | 3.8% ✗ | 2.5% ✓ | 1.5% ✓ | 1.0% ✓ |
| 100 | 5.0% ✗ | 3.4% ✗ | 2.1% ✓ | 1.3% ✓ |
| 150 | 7.5% ✗ | 5.0% ✗ | 3.1% ✗ | 1.9% ✓ |
| 200 | 10.0% ✗ | 6.7% ✗ | 4.1% ✗ | 2.6% ✓ |
| 300 | — | 10.0% ✗ | 6.2% ✗ | 3.9% ✗ |
✓ = within 3% recommendation. ✗ = exceeds 3%. Values at full rated load (20A for 12 AWG, 15A for 14 AWG).
Voltage Drop Chart: 240V, 30A Circuit (Copper)
| Distance (ft) | 10 AWG | 8 AWG | 6 AWG |
|---|---|---|---|
| 50 | 1.3% ✓ | 0.8% ✓ | 0.5% ✓ |
| 100 | 2.5% ✓ | 1.6% ✓ | 1.0% ✓ |
| 150 | 3.8% ✗ | 2.4% ✓ | 1.5% ✓ |
| 200 | 5.0% ✗ | 3.2% ✗ | 2.0% ✓ |
| 300 | 7.5% ✗ | 4.8% ✗ | 3.0% ✓ |
Frequently Asked Questions
How far can you run 12 AWG wire?
For a 20A, 120V circuit: 12 AWG copper can run 50 ft before exceeding 3% voltage drop (2.4V). For 100 ft: use 10 AWG. For 150 ft: use 8 AWG. These assume full 20A load.
What size wire do I need for 200 feet?
For a 20A, 120V circuit at 200 ft: use 6 AWG copper (VD = 2.6%). For a 20A, 240V circuit at 200 ft: use 10 AWG copper (VD = 2.1%). Higher voltage = less drop for the same power.
Does voltage drop affect equipment?
Yes. Motors draw more current at low voltage, overheating and failing early. LED lights may flicker. Electronics may malfunction. Sensitive equipment (computers, medical devices) needs <2% voltage drop.
Disclaimer: For preliminary design only. Verify against local codes and professional engineering requirements.