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🇺🇸 NEC NFPA 70 · Table 310.16 (75°C) · Voltage Drop Analysis

475 Amp Wire Size at 1000 Feet (120V Single-Phase (US Standard Branch))

Complete conductor sizing, Ohm's law voltage drop, $I^2R$ line power loss, and circuit breaker specification for a 475 A load over a 1000 ft (304.8 m) one-way run.

Copper Wire (≤3% Drop)4× 1000 kcmil (Parallel)506.7 mm² · Drop: 2.55%
Aluminum Wire (≤3% Drop)1000 kcmilDrop: 20.17V (16.81%)
Voltage at Load End116.9 VLoss: 3.06 V (1452.2 W)
Power & Breaker (125%)57.0 kW600A Breaker Recommended

All AWG & kcmil Wire Gauges for 475 Amps at 1000 Feet (120V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A2979.13 V (2482.61%)0.0 V4914.17 V (4095.14%)1415085.3 WDrop/Amp High
12 AWG3.31 mm²20 A1872.08 V (1560.07%)0.0 V3088.06 V (2573.38%)889237.9 WDrop/Amp High
10 AWG5.26 mm²30 A1178.06 V (981.71%)0.0 V1943.24 V (1619.37%)559577.5 WDrop/Amp High
8 AWG8.37 mm²50 A740.33 V (616.94%)0.0 V1221.2 V (1017.67%)351658.0 WDrop/Amp High
6 AWG13.3 mm²65 A465.91 V (388.26%)0.0 V768.53 V (640.44%)221306.6 WDrop/Amp High
4 AWG21.15 mm²85 A292.98 V (244.15%)0.0 V483.28 V (402.74%)139166.8 WDrop/Amp High
3 AWG26.67 mm²100 A232.34 V (193.62%)0.0 V383.26 V (319.38%)110362.9 WDrop/Amp High
2 AWG33.62 mm²115 A184.31 V (153.59%)0.0 V304.03 V (253.36%)87548.4 WDrop/Amp High
1 AWG42.41 mm²130 A146.11 V (121.76%)0.0 V241.02 V (200.85%)69402.9 WDrop/Amp High
1/0 AWG53.49 mm²150 A115.85 V (96.54%)4.2 V191.09 V (159.24%)55026.7 WDrop/Amp High
2/0 AWG67.43 mm²175 A91.9 V (76.58%)28.1 V151.59 V (126.32%)43650.9 WDrop/Amp High
3/0 AWG85.01 mm²200 A72.89 V (60.74%)47.1 V120.24 V (100.2%)34623.9 WDrop/Amp High
4/0 AWG107.2 mm²230 A57.8 V (48.17%)62.2 V95.35 V (79.46%)27456.9 WDrop/Amp High
250 kcmil126.7 mm²255 A48.91 V (40.76%)71.1 V80.67 V (67.23%)23231.1 WDrop/Amp High
300 kcmil152.0 mm²285 A40.77 V (33.97%)79.2 V67.25 V (56.04%)19364.3 WDrop/Amp High
350 kcmil177.3 mm²310 A34.95 V (29.12%)85.1 V57.65 V (48.04%)16601.1 WDrop/Amp High
400 kcmil202.7 mm²335 A30.57 V (25.48%)89.4 V50.43 V (42.02%)14520.9 WDrop/Amp High
500 kcmil253.4 mm²380 A24.45 V (20.38%)95.5 V40.34 V (33.61%)11615.5 WDrop/Amp High
600 kcmil304.0 mm²420 A20.38 V (16.99%)99.6 V33.62 V (28.02%)9682.2 WDrop/Amp High
750 kcmil380.0 mm²475 A16.31 V (13.59%)103.7 V26.9 V (22.42%)7745.7 WDrop/Amp High
1000 kcmil506.7 mm²545 A12.23 V (10.19%)107.8 V20.17 V (16.81%)5808.9 WDrop/Amp High

Frequently Asked Engineering Questions

What size copper wire do I need for 475 amps at 1000 feet (120V)?

To stay within the NEC recommended 3% maximum voltage drop for a 475A load over 1000 feet one-way at 120V (1-Phase), you need 4× 1000 kcmil (Parallel) copper wire. This produces a voltage drop of 3.06V (2.55%) and delivers 116.9V at the load.

What size aluminum wire is required for 475 amps at 1000 feet?

Using aluminum conductors (75°C rating), you should use 1000 kcmil to maintain voltage drop at 20.17V (16.81%).

What breaker size is needed for a 475A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (475A × 1.25 = 593.8A), which corresponds to a standard 600A circuit breaker.