10 AWG voltage drop at 300 feet
Computed voltage drop for 10 AWG copper conductors on a 300 ft one-way run.
17.42 V
drop on 10 AWG copper, 300 ft one-way, 24 A load · 14.5% of 120 V · 7.3% of 240 V
10 AWG at 300 ft by load
| Load | Drop | % at 120 V | % at 240 V | 3% rule (240 V) |
|---|---|---|---|---|
| 6 A | 4.36 V | 3.6% | 1.8% | OK |
| 12 A | 8.71 V | 7.3% | 3.6% | OK at 240 V up to 5% |
| 18 A | 13.07 V | 10.9% | 5.4% | Upsize |
| 24 A | 17.42 V | 14.5% | 7.3% | Upsize |
Vd = 2 × length × R × I ÷ 1000, R = 1.21 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 10 AWG wire at 300 feet?
At 24 A (80% of its 30 A 75°C rating) 10 AWG copper drops 17.42 V over 300 ft one-way: 14.5% at 120 V or 7.3% at 240 V.
How far can I run 10 AWG at 24 amps?
To stay within 3% at 120 V, about 62 ft one-way; at 240 V about 124 ft.