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

650 Amp Wire Size at 225 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 650 A load over a 225 ft (68.6 m) one-way run.

Copper Wire (≤3% Drop)2× 1000 kcmil (Parallel)506.7 mm² · Drop: 1.57%
Aluminum Wire (≤3% Drop)1000 kcmilDrop: 6.21V (5.18%)
Voltage at Load End118.1 VLoss: 1.89 V (1223.8 W)
Power & Breaker (125%)78.0 kW1000A Breaker Recommended

All AWG & kcmil Wire Gauges for 650 Amps at 225 Feet (120V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A917.26 V (764.38%)0.0 V1513.05 V (1260.87%)596217.4 WDrop/Amp High
12 AWG3.31 mm²20 A576.4 V (480.34%)0.0 V950.8 V (792.33%)374662.3 WDrop/Amp High
10 AWG5.26 mm²30 A362.72 V (302.26%)0.0 V598.31 V (498.6%)235766.6 WDrop/Amp High
8 AWG8.37 mm²50 A227.94 V (189.95%)0.0 V376.0 V (313.33%)148163.9 WDrop/Amp High
6 AWG13.3 mm²65 A143.45 V (119.54%)0.0 V236.63 V (197.19%)93243.0 WDrop/Amp High
4 AWG21.15 mm²85 A90.21 V (75.17%)29.8 V148.8 V (124.0%)58635.1 WDrop/Amp High
3 AWG26.67 mm²100 A71.54 V (59.61%)48.5 V118.0 V (98.34%)46499.1 WDrop/Amp High
2 AWG33.62 mm²115 A56.75 V (47.29%)63.3 V93.61 V (78.01%)36886.7 WDrop/Amp High
1 AWG42.41 mm²130 A44.99 V (37.49%)75.0 V74.21 V (61.84%)29241.5 WDrop/Amp High
1/0 AWG53.49 mm²150 A35.67 V (29.72%)84.3 V58.84 V (49.03%)23184.4 WDrop/Amp High
2/0 AWG67.43 mm²175 A28.29 V (23.58%)91.7 V46.67 V (38.89%)18391.4 WDrop/Amp High
3/0 AWG85.01 mm²200 A22.44 V (18.7%)97.6 V37.02 V (30.85%)14588.1 WDrop/Amp High
4/0 AWG107.2 mm²230 A17.8 V (14.83%)102.2 V29.36 V (24.46%)11568.4 WDrop/Amp High
250 kcmil126.7 mm²255 A15.06 V (12.55%)104.9 V24.84 V (20.7%)9787.9 WDrop/Amp High
300 kcmil152.0 mm²285 A12.55 V (10.46%)107.4 V20.7 V (17.25%)8158.8 WDrop/Amp High
350 kcmil177.3 mm²310 A10.76 V (8.97%)109.2 V17.75 V (14.79%)6994.5 WDrop/Amp High
400 kcmil202.7 mm²335 A9.41 V (7.84%)110.6 V15.53 V (12.94%)6118.1 WDrop/Amp High
500 kcmil253.4 mm²380 A7.53 V (6.27%)112.5 V12.42 V (10.35%)4894.0 WDrop/Amp High
600 kcmil304.0 mm²420 A6.28 V (5.23%)113.7 V10.35 V (8.63%)4079.4 WDrop/Amp High
750 kcmil380.0 mm²475 A5.02 V (4.18%)115.0 V8.28 V (6.9%)3263.5 WDrop/Amp High
1000 kcmil506.7 mm²545 A3.77 V (3.14%)116.2 V6.21 V (5.18%)2447.5 WDrop/Amp High

Frequently Asked Engineering Questions

What size copper wire do I need for 650 amps at 225 feet (120V)?

To stay within the NEC recommended 3% maximum voltage drop for a 650A load over 225 feet one-way at 120V (1-Phase), you need 2× 1000 kcmil (Parallel) copper wire. This produces a voltage drop of 1.89V (1.57%) and delivers 118.1V at the load.

What size aluminum wire is required for 650 amps at 225 feet?

Using aluminum conductors (75°C rating), you should use 1000 kcmil to maintain voltage drop at 6.21V (5.18%).

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.