Voltage drop scenario

Wire size for 50 amps at 100 feet

At 240 V single-phase, copper 6 AWG keeps a 50 amps load at about 2.05% drop over 100 feet — within the 3% design target used here. Adjust material, voltage, or phase below.

Phase

Voltage drop

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Enter a run to estimate voltage drop.

Estimated results
Voltage drop —
Percent drop —
Voltage at load —
Resistance used —
NEC 3% branch NEC 5% total
Estimate only — not a substitute for a licensed electrician. Based on NEC Ch.9 Table 8 DC resistance. Does not model ampacity, temperature derating, power factor, or continuous-load factors. Verify against the current NEC and your local code / AHJ.

50 amps at 100 feet: the short answer

At 240 V single-phase over 100 feet, a 50 amps load needs copper 6 AWG to stay near 2.05% — inside the 3% design target used for this comparison. For comparison, copper 12 AWG would drop about 19.30 V (8.04%) on the same run.

Before you pull wire

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.

Where this 50 amps, 100 feet scenario fits

This combination commonly appears while budgeting a 240 V receptacle, welder, cooking appliance, or EV-charging circuit. Those loads do not all size the same way: a receptacle rating, breaker rating, and continuous charging current are three different inputs.

Before buying wire, decide which current belongs in the calculation. For example, an EV charger on a nominal circuit may be configured below the breaker rating because charging is a continuous load. Enter the actual design current and then complete the separate ampacity and continuous-load checks.

Distance changes the conductor decision

Copper recommendations for a 50 amps load at 240 V single-phase, using the same 3% target
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%

Checks specific to this project

  • Do not automatically enter 50 A just because the receptacle face says 50 A.
  • For EV charging, use the configured continuous output and verify the equipment instructions.
  • Confirm whether the load is hardwired or cord-and-plug connected and whether neutral is required.
  • Compare copper and aluminum only after checking that every termination is listed for the chosen material.

FAQ

What wire size do I need for 50 amps at 100 feet?

For voltage drop at 240 V single-phase, copper 6 AWG keeps a 50 amps load near 2.05% over 100 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.

How much voltage drop does 50 amps over 100 feet have?

On a baseline copper 12 AWG at 240 V single-phase, 50 amps over 100 feet drops about 19.30 V (8.04%). Larger conductors drop less; the calculator shows the exact figure for any size.

Is this voltage-drop sizing the same as ampacity sizing?

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).

Sources & verification

Source links and page assumptions reviewed .

Wire size for 20 amps at 100 feetWire size for 30 amps at 150 feetWire size for 50 amps at 200 feetWire size for 60 amps at 100 feetWire size for 100 amps at 100 feet All voltage drop scenarios How to calculate voltage drop

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.