12 AWG voltage drop at 25 feet
Computed voltage drop for 12 AWG copper conductors on a 25 ft one-way run.
1.54 V
drop on 12 AWG copper, 25 ft one-way, 16 A load · 1.3% of 120 V · 0.6% of 240 V
12 AWG at 25 ft by load
| Load | Drop | % at 120 V | % at 240 V | 3% rule (240 V) |
|---|---|---|---|---|
| 4 A | 0.39 V | 0.3% | 0.2% | OK |
| 8 A | 0.77 V | 0.6% | 0.3% | OK |
| 12 A | 1.16 V | 1.0% | 0.5% | OK |
| 16 A | 1.54 V | 1.3% | 0.6% | OK |
Vd = 2 × length × R × I ÷ 1000, R = 1.93 Ω/1000 ft (copper, NEC Ch. 9 Table 8). Aluminum is about 1.6× higher.
Same wire, other distances
50 ft · 75 ft · 100 ft · 125 ft · 150 ft · 200 ft · 250 ft · 300 ft
FAQ
What is the voltage drop on 12 AWG wire at 25 feet?
At 16 A (80% of its 20 A 75°C rating) 12 AWG copper drops 1.54 V over 25 ft one-way: 1.3% at 120 V or 0.6% at 240 V.
How far can I run 12 AWG at 16 amps?
To stay within 3% at 120 V, about 58 ft one-way; at 240 V about 117 ft.