14 AWG voltage drop at 300 feet
Computed voltage drop for 14 AWG copper conductors on a 300 ft one-way run.
22.10 V
drop on 14 AWG copper, 300 ft one-way, 12 A load · 18.4% of 120 V · 9.2% of 240 V
14 AWG at 300 ft by load
| Load | Drop | % at 120 V | % at 240 V | 3% rule (240 V) |
|---|---|---|---|---|
| 3 A | 5.53 V | 4.6% | 2.3% | OK |
| 6 A | 11.05 V | 9.2% | 4.6% | OK at 240 V up to 5% |
| 9 A | 16.58 V | 13.8% | 6.9% | Upsize |
| 12 A | 22.10 V | 18.4% | 9.2% | Upsize |
Vd = 2 × length × R × I ÷ 1000, R = 3.07 Ω/1000 ft (copper, NEC Ch. 9 Table 8). Aluminum is about 1.6× higher.
Same wire, other distances
25 ft · 50 ft · 75 ft · 100 ft · 125 ft · 150 ft · 200 ft · 250 ft
FAQ
What is the voltage drop on 14 AWG wire at 300 feet?
At 12 A (80% of its 15 A 75°C rating) 14 AWG copper drops 22.10 V over 300 ft one-way: 18.4% at 120 V or 9.2% at 240 V.
How far can I run 14 AWG at 12 amps?
To stay within 3% at 120 V, about 49 ft one-way; at 240 V about 98 ft.