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

650 Amp Wire Size at 600 Feet (208V Three-Phase (US Commercial Wye))

Complete conductor sizing, Ohm's law voltage drop, $I^2R$ line power loss, and circuit breaker specification for a 650 A load over a 600 ft (182.9 m) one-way run.

Copper Wire (≤3% Drop)2× 1000 kcmil (Parallel)506.7 mm² · Drop: 2.09%
Aluminum Wire (≤3% Drop)1000 kcmilDrop: 14.34V (6.9%)
Voltage at Load End203.7 VLoss: 4.35 V (4894.9 W)
Power & Breaker (125%)234.17 kW1000A Breaker Recommended

All AWG & kcmil Wire Gauges for 650 Amps at 600 Feet (208V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A2118.32 V (1018.42%)0.0 V3494.23 V (1679.92%)2384869.5 WDrop/Amp High
12 AWG3.31 mm²20 A1331.15 V (639.97%)0.0 V2195.77 V (1055.66%)1498649.1 WDrop/Amp High
10 AWG5.26 mm²30 A837.66 V (402.72%)0.0 V1381.75 V (664.3%)943066.3 WDrop/Amp High
8 AWG8.37 mm²50 A526.42 V (253.08%)0.0 V868.34 V (417.47%)592655.7 WDrop/Amp High
6 AWG13.3 mm²65 A331.29 V (159.27%)0.0 V546.47 V (262.72%)372972.1 WDrop/Amp High
4 AWG21.15 mm²85 A208.33 V (100.16%)0.0 V343.64 V (165.21%)234540.4 WDrop/Amp High
3 AWG26.67 mm²100 A165.21 V (79.43%)42.8 V272.52 V (131.02%)185996.6 WDrop/Amp High
2 AWG33.62 mm²115 A131.06 V (63.01%)76.9 V216.18 V (103.93%)147547.0 WDrop/Amp High
1 AWG42.41 mm²130 A103.89 V (49.95%)104.1 V171.37 V (82.39%)116966.0 WDrop/Amp High
1/0 AWG53.49 mm²150 A82.37 V (39.6%)125.6 V135.88 V (65.32%)92737.5 WDrop/Amp High
2/0 AWG67.43 mm²175 A65.34 V (31.42%)142.7 V107.79 V (51.82%)73565.6 WDrop/Amp High
3/0 AWG85.01 mm²200 A51.83 V (24.92%)156.2 V85.5 V (41.1%)58352.3 WDrop/Amp High
4/0 AWG107.2 mm²230 A41.1 V (19.76%)166.9 V67.8 V (32.6%)46273.6 WDrop/Amp High
250 kcmil126.7 mm²255 A34.78 V (16.72%)173.2 V57.36 V (27.58%)39151.8 WDrop/Amp High
300 kcmil152.0 mm²285 A28.99 V (13.94%)179.0 V47.82 V (22.99%)32635.1 WDrop/Amp High
350 kcmil177.3 mm²310 A24.85 V (11.95%)183.1 V40.99 V (19.71%)27978.2 WDrop/Amp High
400 kcmil202.7 mm²335 A21.74 V (10.45%)186.3 V35.86 V (17.24%)24472.3 WDrop/Amp High
500 kcmil253.4 mm²380 A17.39 V (8.36%)190.6 V28.68 V (13.79%)19575.9 WDrop/Amp High
600 kcmil304.0 mm²420 A14.49 V (6.97%)193.5 V23.91 V (11.49%)16317.5 WDrop/Amp High
750 kcmil380.0 mm²475 A11.59 V (5.57%)196.4 V19.13 V (9.2%)13054.0 WDrop/Amp High
1000 kcmil506.7 mm²545 A8.7 V (4.18%)199.3 V14.34 V (6.9%)9789.9 WDrop/Amp High

Frequently Asked Engineering Questions

What size copper wire do I need for 650 amps at 600 feet (208V)?

To stay within the NEC recommended 3% maximum voltage drop for a 650A load over 600 feet one-way at 208V (3-Phase), you need 2× 1000 kcmil (Parallel) copper wire. This produces a voltage drop of 4.35V (2.09%) and delivers 203.7V at the load.

What size aluminum wire is required for 650 amps at 600 feet?

Using aluminum conductors (75°C rating), you should use 1000 kcmil to maintain voltage drop at 14.34V (6.9%).

What breaker size is needed for a 650A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (650A × 1.25 = 812.5A), which corresponds to a standard 1000A circuit breaker.