Wire Size for 85 Amps
Typical copper and aluminum wire gauges for 85 amps across common run lengths on a 120V circuit, sized to keep voltage drop under 3% and respect the NEC 240.4(D) small-conductor rule. Actual install sizing depends on conductor material, insulation/termination temperature rating, cable type, ambient and bundling derates, and local code.
85A Wire Gauge by Distance
| Distance | Copper Gauge | Aluminum Gauge | V-Drop (Cu) | NEC Status |
|---|---|---|---|---|
| 25 ft | 4 AWG | 2 AWG | 1.31V (1.09%) | OK |
| 50 ft | 4 AWG | 2 AWG | 2.62V (2.18%) | OK |
| 75 ft | 3 AWG | 2 AWG | 3.12V (2.6%) | OK |
| 100 ft | 2 AWG | 1 AWG | 3.3V (2.75%) | OK |
| 125 ft | 1 AWG | 1/0 AWG | 3.27V (2.73%) | OK |
| 150 ft | 1/0 AWG | 2/0 AWG | 3.11V (2.59%) | OK |
| 175 ft | 2/0 AWG | 3/0 AWG | 2.88V (2.4%) | OK |
| 200 ft | 2/0 AWG | 3/0 AWG | 3.29V (2.74%) | OK |
| 250 ft | 3/0 AWG | 4/0 AWG | 3.26V (2.71%) | OK |
| 300 ft | 4/0 AWG | 350 kcmil | 3.1V (2.58%) | OK |
| 400 ft | 250 kcmil | 500 kcmil | 3.5V (2.92%) | OK |
| 500 ft | 350 kcmil | 500 kcmil | 3.12V (2.6%) | OK |
Aluminum is not typical for 10 AWG and smaller branch-circuit conductors in residential settings. Copper gauges use the NEC 240.4(D) branch-circuit cap, not raw 75°C ampacity.
Also Calculate
Other Amperages
This calculator provides estimates for reference purposes only. Always consult a licensed electrician and verify compliance with the National Electrical Code (NEC) and local electrical codes before performing any electrical work.