Wire Size for 249 Amps
Typical copper and aluminum wire gauges for 249 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.
249A Wire Gauge by Distance
| Distance | Copper Gauge | Aluminum Gauge | V-Drop (Cu) | NEC Status |
|---|---|---|---|---|
| 25 ft | 250 kcmil | 350 kcmil | 0.6412V (0.5343%) | OK |
| 50 ft | 250 kcmil | 350 kcmil | 1.28V (1.07%) | OK |
| 75 ft | 250 kcmil | 350 kcmil | 1.92V (1.6%) | OK |
| 100 ft | 250 kcmil | 350 kcmil | 2.56V (2.14%) | OK |
| 125 ft | 250 kcmil | 500 kcmil | 3.21V (2.67%) | OK |
| 150 ft | 300 kcmil | 500 kcmil | 3.2V (2.67%) | OK |
| 175 ft | 350 kcmil | 750 kcmil | 3.2V (2.67%) | OK |
| 200 ft | 500 kcmil | 750 kcmil | 2.57V (2.14%) | OK |
| 250 ft | 500 kcmil | 750 kcmil | 3.21V (2.68%) | OK |
| 300 ft | 750 kcmil | no aluminum pick | 2.55V (2.13%) | OK |
| 400 ft | 750 kcmil | no aluminum pick | 3.41V (2.84%) | OK |
| 500 ft | Exceeds available gauges | |||
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.