Wire Size for 0.4 Amps

Typical copper wire gauges for 0.4 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. At 0.4A the load sits in residential-branch territory where aluminum is not a typical conductor, so the table lists copper only. Actual install sizing depends on conductor material, insulation/termination temperature rating, cable type, ambient and bundling derates, and local code.

0.4A Wire Gauge by Distance

Distance	Copper Gauge	V-Drop (Cu)	NEC Status
25 ft	14 AWG	0.0628V (0.0523%)	check_circle OK
50 ft	14 AWG	0.1256V (0.1047%)	check_circle OK
75 ft	14 AWG	0.1884V (0.157%)	check_circle OK
100 ft	14 AWG	0.2512V (0.2093%)	check_circle OK
125 ft	14 AWG	0.314V (0.2617%)	check_circle OK
150 ft	14 AWG	0.3768V (0.314%)	check_circle OK
175 ft	14 AWG	0.4396V (0.3663%)	check_circle OK
200 ft	14 AWG	0.5024V (0.4187%)	check_circle OK
250 ft	14 AWG	0.628V (0.5233%)	check_circle OK
300 ft	14 AWG	0.7536V (0.628%)	check_circle OK
400 ft	14 AWG	1V (0.8373%)	check_circle OK
500 ft	14 AWG	1.26V (1.05%)	check_circle OK

Copper gauges use the NEC 240.4(D) branch-circuit cap, not raw 75°C ampacity.

Also Calculate

electric_bolt 0.4A 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.