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

700 Amp Wire Size at 225 Feet (240V Three-Phase (US Industrial Delta))

Complete conductor sizing, Ohm's law voltage drop, $I^2R$ line power loss, and circuit breaker specification for a 700 A load over a 225 ft (68.6 m) one-way run.

Copper Wire (≤3% Drop)2× 1000 kcmil (Parallel)506.7 mm² · Drop: 0.73%
Aluminum Wire (≤3% Drop)1000 kcmilDrop: 5.79V (2.41%)
Voltage at Load End238.2 VLoss: 1.75 V (2128.8 W)
Power & Breaker (125%)290.98 kW1000A Breaker Recommended

All AWG & kcmil Wire Gauges for 700 Amps at 225 Feet (240V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A855.47 V (356.45%)0.0 V1411.13 V (587.97%)1037206.6 WDrop/Amp High
12 AWG3.31 mm²20 A537.58 V (223.99%)0.0 V886.75 V (369.48%)651779.3 WDrop/Amp High
10 AWG5.26 mm²30 A338.29 V (140.95%)0.0 V558.01 V (232.51%)410150.1 WDrop/Amp High
8 AWG8.37 mm²50 A212.59 V (88.58%)27.4 V350.68 V (146.11%)257752.6 WDrop/Amp High
6 AWG13.3 mm²65 A133.79 V (55.75%)106.2 V220.69 V (91.95%)162209.7 WDrop/Amp High
4 AWG21.15 mm²85 A84.13 V (35.05%)155.9 V138.78 V (57.82%)102004.2 WDrop/Amp High
3 AWG26.67 mm²100 A66.72 V (27.8%)173.3 V110.05 V (45.86%)80892.0 WDrop/Amp High
2 AWG33.62 mm²115 A52.93 V (22.05%)187.1 V87.3 V (36.38%)64169.8 WDrop/Amp High
1 AWG42.41 mm²130 A41.96 V (17.48%)198.0 V69.21 V (28.84%)50869.8 WDrop/Amp High
1/0 AWG53.49 mm²150 A33.27 V (13.86%)206.7 V54.87 V (22.86%)40332.6 WDrop/Amp High
2/0 AWG67.43 mm²175 A26.39 V (11.0%)213.6 V43.53 V (18.14%)31994.5 WDrop/Amp High
3/0 AWG85.01 mm²200 A20.93 V (8.72%)219.1 V34.53 V (14.39%)25378.1 WDrop/Amp High
4/0 AWG107.2 mm²230 A16.6 V (6.92%)223.4 V27.38 V (11.41%)20124.9 WDrop/Amp High
250 kcmil126.7 mm²255 A14.04 V (5.85%)226.0 V23.17 V (9.65%)17027.5 WDrop/Amp High
300 kcmil152.0 mm²285 A11.71 V (4.88%)228.3 V19.31 V (8.05%)14193.4 WDrop/Amp High
350 kcmil177.3 mm²310 A10.04 V (4.18%)230.0 V16.55 V (6.9%)12168.0 WDrop/Amp High
400 kcmil202.7 mm²335 A8.78 V (3.66%)231.2 V14.48 V (6.03%)10643.3 WDrop/Amp High
500 kcmil253.4 mm²380 A7.02 V (2.93%)233.0 V11.58 V (4.83%)8513.8 WDrop/Amp High
600 kcmil304.0 mm²420 A5.85 V (2.44%)234.1 V9.66 V (4.02%)7096.7 WDrop/Amp High
750 kcmil380.0 mm²475 A4.68 V (1.95%)235.3 V7.72 V (3.22%)5677.3 WDrop/Amp High
1000 kcmil506.7 mm²545 A3.51 V (1.46%)236.5 V5.79 V (2.41%)4257.7 WDrop/Amp High

Frequently Asked Engineering Questions

What size copper wire do I need for 700 amps at 225 feet (240V)?

To stay within the NEC recommended 3% maximum voltage drop for a 700A load over 225 feet one-way at 240V (3-Phase), you need 2× 1000 kcmil (Parallel) copper wire. This produces a voltage drop of 1.75V (0.73%) and delivers 238.2V at the load.

What size aluminum wire is required for 700 amps at 225 feet?

Using aluminum conductors (75°C rating), you should use 1000 kcmil to maintain voltage drop at 5.79V (2.41%).

What breaker size is needed for a 700A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (700A × 1.25 = 875.0A), which corresponds to a standard 1000A circuit breaker.