Wire Size for 304 Amps

Typical copper and aluminum wire gauges for 304 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.

304A Wire Gauge by Distance

Distance	Copper Gauge	Aluminum Gauge	V-Drop (Cu)	NEC Status
25 ft	350 kcmil	500 kcmil	0.5578V (0.4649%)	check_circle OK
50 ft	350 kcmil	500 kcmil	1.12V (0.9297%)	check_circle OK
75 ft	350 kcmil	500 kcmil	1.67V (1.39%)	check_circle OK
100 ft	350 kcmil	500 kcmil	2.23V (1.86%)	check_circle OK
125 ft	350 kcmil	500 kcmil	2.79V (2.32%)	check_circle OK
150 ft	350 kcmil	750 kcmil	3.35V (2.79%)	check_circle OK
175 ft	500 kcmil	750 kcmil	2.75V (2.29%)	check_circle OK
200 ft	500 kcmil	750 kcmil	3.14V (2.61%)	check_circle OK
250 ft	750 kcmil	no aluminum pick	2.6V (2.17%)	check_circle OK
300 ft	750 kcmil	no aluminum pick	3.12V (2.6%)	check_circle OK
400 ft	Exceeds available gauges
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

electric_bolt 304A to watts at 120V trending_down Voltage drop calculator

Other Amperages

10A 15A 20A 25A 30A 40A 50A 60A 70A 80A 100A 125A 150A 175A 200A 225A 250A 300A 350A 400A

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.