1/0 AWG voltage drop at 125 feet
Computed voltage drop for 1/0 AWG copper conductors on a 125 ft one-way run.
3.66 V
drop on 1/0 AWG copper, 125 ft one-way, 120 A load · 3.1% of 120 V · 1.5% of 240 V
1/0 AWG at 125 ft by load
| Load | Drop | % at 120 V | % at 240 V | 3% rule (240 V) |
|---|---|---|---|---|
| 30 A | 0.92 V | 0.8% | 0.4% | OK |
| 60 A | 1.83 V | 1.5% | 0.8% | OK |
| 90 A | 2.75 V | 2.3% | 1.1% | OK |
| 120 A | 3.66 V | 3.1% | 1.5% | OK |
Vd = 2 × length × R × I ÷ 1000, R = 0.122 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 · 150 ft · 200 ft · 250 ft · 300 ft
FAQ
What is the voltage drop on 1/0 AWG wire at 125 feet?
At 120 A (80% of its 150 A 75°C rating) 1/0 AWG copper drops 3.66 V over 125 ft one-way: 3.1% at 120 V or 1.5% at 240 V.
How far can I run 1/0 AWG at 120 amps?
To stay within 3% at 120 V, about 123 ft one-way; at 240 V about 246 ft.