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

500 Amp Wire Size at 200 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 500 A load over a 200 ft (61.0 m) one-way run.

Copper Wire (≤3% Drop)1000 kcmil506.7 mm² · Drop: 2.15%
Aluminum Wire (≤3% Drop)1000 kcmilDrop: 4.25V (3.54%)
Voltage at Load End117.4 VLoss: 2.57 V (1287.3 W)
Power & Breaker (125%)60.0 kW700A Breaker Recommended

All AWG & kcmil Wire Gauges for 500 Amps at 200 Feet (120V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A627.18 V (522.65%)0.0 V1034.56 V (862.13%)313592.3 WDrop/Amp High
12 AWG3.31 mm²20 A394.12 V (328.44%)0.0 V650.12 V (541.76%)197061.0 WDrop/Amp High
10 AWG5.26 mm²30 A248.01 V (206.68%)0.0 V409.1 V (340.92%)124006.1 WDrop/Amp High
8 AWG8.37 mm²50 A155.86 V (129.88%)0.0 V257.1 V (214.25%)77929.7 WDrop/Amp High
6 AWG13.3 mm²65 A98.09 V (81.74%)21.9 V161.8 V (134.83%)49043.0 WDrop/Amp High
4 AWG21.15 mm²85 A61.68 V (51.4%)58.3 V101.74 V (84.79%)30840.3 WDrop/Amp High
3 AWG26.67 mm²100 A48.91 V (40.76%)71.1 V80.69 V (67.24%)24457.1 WDrop/Amp High
2 AWG33.62 mm²115 A38.8 V (32.34%)81.2 V64.01 V (53.34%)19401.3 WDrop/Amp High
1 AWG42.41 mm²130 A30.76 V (25.63%)89.2 V50.74 V (42.28%)15380.1 WDrop/Amp High
1/0 AWG53.49 mm²150 A24.39 V (20.32%)95.6 V40.23 V (33.52%)12194.3 WDrop/Amp High
2/0 AWG67.43 mm²175 A19.35 V (16.12%)100.7 V31.91 V (26.59%)9673.3 WDrop/Amp High
3/0 AWG85.01 mm²200 A15.35 V (12.79%)104.7 V25.31 V (21.09%)7672.9 WDrop/Amp High
4/0 AWG107.2 mm²230 A12.17 V (10.14%)107.8 V20.07 V (16.73%)6084.6 WDrop/Amp High
250 kcmil126.7 mm²255 A10.3 V (8.58%)109.7 V16.98 V (14.15%)5148.2 WDrop/Amp High
300 kcmil152.0 mm²285 A8.58 V (7.15%)111.4 V14.16 V (11.8%)4291.3 WDrop/Amp High
350 kcmil177.3 mm²310 A7.36 V (6.13%)112.6 V12.14 V (10.11%)3678.9 WDrop/Amp High
400 kcmil202.7 mm²335 A6.44 V (5.36%)113.6 V10.62 V (8.85%)3217.9 WDrop/Amp High
500 kcmil253.4 mm²380 A5.15 V (4.29%)114.9 V8.49 V (7.08%)2574.1 WDrop/Amp High
600 kcmil304.0 mm²420 A4.29 V (3.58%)115.7 V7.08 V (5.9%)2145.6 WDrop/Amp High
750 kcmil380.0 mm²475 A3.43 V (2.86%)116.6 V5.66 V (4.72%)1716.5 WDrop/Amp High
1000 kcmil506.7 mm²545 A2.57 V (2.15%)117.4 V4.25 V (3.54%)1287.3 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 500 amps at 200 feet (120V)?

To stay within the NEC recommended 3% maximum voltage drop for a 500A load over 200 feet one-way at 120V (1-Phase), you need 1000 kcmil copper wire. This produces a voltage drop of 2.57V (2.15%) and delivers 117.4V at the load.

What size aluminum wire is required for 500 amps at 200 feet?

Using aluminum conductors (75°C rating), you should use 1000 kcmil to maintain voltage drop at 4.25V (3.54%).

What breaker size is needed for a 500A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (500A × 1.25 = 625.0A), which corresponds to a standard 700A circuit breaker.