Voltage drop scenario
At 240 V single-phase, copper 4 AWG keeps a 50 amps load at about 2.57% drop over 200 feet — within the 3% design target used here. Adjust material, voltage, or phase below.
Voltage drop
—Enter a run to estimate voltage drop.
| Voltage drop | — |
|---|---|
| Percent drop | — |
| Voltage at load | — |
| Resistance used | — |
At 240 V single-phase over 200 feet, a 50 amps load needs copper 4 AWG to stay near 2.57% — inside the 3% design target used for this comparison. For comparison, copper 12 AWG would drop about 38.60 V (16.08%) on the same run.
This is a voltage-drop estimate only. The conductor must also meet ampacity, temperature derating, and overcurrent rules — use the larger of the voltage-drop size and the ampacity size. Aluminum of the same size drops more, so it usually needs to go up one or two sizes. Always confirm with a licensed electrician and your local code (AHJ).
Sized for voltage drop using NEC Ch.9 Table 8 DC resistance. The 3% figure is a common design target from informational guidance, not a substitute for a code review.
Two hundred feet turns a familiar 50 A circuit into a long-run project. It may represent an outbuilding, remote equipment pad, gate, pump, or distant charging location where conductor cost and voltage performance both matter.
This is the point where alternatives deserve a written comparison: a larger conductor, a different equipment location, a feeder with a local subpanel, or a revised load. The cheapest conductor that carries current may not deliver acceptable voltage at the far end, especially when equipment has motors or electronics.
| One-way distance | Suggested copper size | Calculated drop |
|---|---|---|
| 50 ft | 10 AWG | 2.52% |
| 100 ft | 6 AWG | 2.05% |
| 150 ft | 4 AWG | 1.93% |
| 200 ft | 4 AWG | 2.57% |
For voltage drop at 240 V single-phase, copper 4 AWG keeps a 50 amps load near 2.57% over 200 feet, meeting the 3% design target used on this page. Ampacity, derating, equipment instructions, and local code may require a different size — confirm with a licensed electrician.
On a baseline copper 12 AWG at 240 V single-phase, 50 amps over 200 feet drops about 38.60 V (16.08%). Larger conductors drop less; the calculator shows the exact figure for any size.
No. This page sizes for voltage drop only, using NEC Chapter 9 Table 8 DC resistance. The conductor must also satisfy ampacity, temperature derating, and overcurrent-protection rules. Use the larger of the voltage-drop size and the ampacity size, and verify with your local code (AHJ).
Source links and page assumptions reviewed .
Estimate only, based on NEC Chapter 9 Table 8 DC resistance. Not a substitute for a licensed electrician or your local code (AHJ). Voltage-drop sizing does not replace ampacity, temperature derating, power factor, or continuous-load checks. Verify against the current NEC and local code before wiring. Based on NEC Ch.9 Table 8.