Wire Size for 137.5 Amps
Typical copper and aluminum wire gauges for 137.5 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.
137.5A Wire Gauge by Distance
| Distance | Copper Gauge | Aluminum Gauge | V-Drop (Cu) | NEC Status |
|---|---|---|---|---|
| 25 ft | 1/0 AWG | 3/0 AWG | 0.8388V (0.699%) | OK |
| 50 ft | 1/0 AWG | 3/0 AWG | 1.68V (1.4%) | OK |
| 75 ft | 1/0 AWG | 3/0 AWG | 2.52V (2.1%) | OK |
| 100 ft | 1/0 AWG | 3/0 AWG | 3.36V (2.8%) | OK |
| 125 ft | 2/0 AWG | 3/0 AWG | 3.32V (2.77%) | OK |
| 150 ft | 3/0 AWG | 4/0 AWG | 3.16V (2.63%) | OK |
| 175 ft | 4/0 AWG | 300 kcmil | 2.93V (2.44%) | OK |
| 200 ft | 4/0 AWG | 350 kcmil | 3.34V (2.79%) | OK |
| 250 ft | 250 kcmil | 500 kcmil | 3.54V (2.95%) | OK |
| 300 ft | 300 kcmil | 500 kcmil | 3.54V (2.95%) | OK |
| 400 ft | 500 kcmil | 750 kcmil | 2.84V (2.37%) | OK |
| 500 ft | 500 kcmil | no aluminum pick | 3.55V (2.96%) | 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.