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

650 Amp Wire Size at 60 Feet (12V DC (Solar / Automotive / Marine))

Complete conductor sizing, Ohm's law voltage drop, $I^2R$ line power loss, and circuit breaker specification for a 650 A load over a 60 ft (18.3 m) one-way run.

Copper Wire (≤3% Drop)3× 1000 kcmil (Parallel)506.7 mm² · Drop: 2.79%
Aluminum Wire (≤3% Drop)1000 kcmilDrop: 1.66V (13.8%)
Voltage at Load End11.7 VLoss: 0.33 V (217.6 W)
Power & Breaker (125%)7.8 kW1000A Breaker Recommended

All AWG & kcmil Wire Gauges for 650 Amps at 60 Feet (12V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A244.6 V (2038.35%)0.0 V403.48 V (3362.32%)158991.3 WDrop/Amp High
12 AWG3.31 mm²20 A153.71 V (1280.9%)0.0 V253.55 V (2112.88%)99909.9 WDrop/Amp High
10 AWG5.26 mm²30 A96.72 V (806.04%)0.0 V159.55 V (1329.59%)62871.1 WDrop/Amp High
8 AWG8.37 mm²50 A60.79 V (506.54%)0.0 V100.27 V (835.56%)39510.4 WDrop/Amp High
6 AWG13.3 mm²65 A38.25 V (318.78%)0.0 V63.1 V (525.84%)24864.8 WDrop/Amp High
4 AWG21.15 mm²85 A24.06 V (200.46%)0.0 V39.68 V (330.67%)15636.0 WDrop/Amp High
3 AWG26.67 mm²100 A19.08 V (158.97%)0.0 V31.47 V (262.23%)12399.8 WDrop/Amp High
2 AWG33.62 mm²115 A15.13 V (126.11%)0.0 V24.96 V (208.02%)9836.5 WDrop/Amp High
1 AWG42.41 mm²130 A12.0 V (99.97%)0.0 V19.79 V (164.91%)7797.7 WDrop/Amp High
1/0 AWG53.49 mm²150 A9.51 V (79.26%)2.5 V15.69 V (130.75%)6182.5 WDrop/Amp High
2/0 AWG67.43 mm²175 A7.55 V (62.88%)4.5 V12.45 V (103.72%)4904.4 WDrop/Amp High
3/0 AWG85.01 mm²200 A5.98 V (49.87%)6.0 V9.87 V (82.27%)3890.2 WDrop/Amp High
4/0 AWG107.2 mm²230 A4.75 V (39.55%)7.3 V7.83 V (65.24%)3084.9 WDrop/Amp High
250 kcmil126.7 mm²255 A4.02 V (33.46%)8.0 V6.62 V (55.2%)2610.1 WDrop/Amp High
300 kcmil152.0 mm²285 A3.35 V (27.89%)8.7 V5.52 V (46.01%)2175.7 WDrop/Amp High
350 kcmil177.3 mm²310 A2.87 V (23.91%)9.1 V4.73 V (39.45%)1865.2 WDrop/Amp High
400 kcmil202.7 mm²335 A2.51 V (20.92%)9.5 V4.14 V (34.5%)1631.5 WDrop/Amp High
500 kcmil253.4 mm²380 A2.01 V (16.73%)10.0 V3.31 V (27.6%)1305.1 WDrop/Amp High
600 kcmil304.0 mm²420 A1.67 V (13.95%)10.3 V2.76 V (23.01%)1087.8 WDrop/Amp High
750 kcmil380.0 mm²475 A1.34 V (11.16%)10.7 V2.21 V (18.4%)870.3 WDrop/Amp High
1000 kcmil506.7 mm²545 A1.0 V (8.37%)11.0 V1.66 V (13.8%)652.7 WDrop/Amp High

Frequently Asked Engineering Questions

What size copper wire do I need for 650 amps at 60 feet (12V)?

To stay within the NEC recommended 3% maximum voltage drop for a 650A load over 60 feet one-way at 12V (DC), you need 3× 1000 kcmil (Parallel) copper wire. This produces a voltage drop of 0.33V (2.79%) and delivers 11.7V at the load.

What size aluminum wire is required for 650 amps at 60 feet?

Using aluminum conductors (75°C rating), you should use 1000 kcmil to maintain voltage drop at 1.66V (13.8%).

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.