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

30 Amp Wire Size at 200 Feet (480V Three-Phase (US Heavy Industrial))

Complete conductor sizing, Ohm's law voltage drop, $I^2R$ line power loss, and circuit breaker specification for a 30 A load over a 200 ft (61.0 m) one-way run.

Copper Wire (≤3% Drop)10 AWG5.26 mm² · Drop: 2.68%
Aluminum Wire (≤3% Drop)8 AWGDrop: 13.36V (2.78%)
Voltage at Load End467.1 VLoss: 12.89 V (669.6 W)
Power & Breaker (125%)24.94 kW40A Breaker Recommended

All AWG & kcmil Wire Gauges for 30 Amps at 200 Feet (480V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A32.59 V (6.79%)447.4 V53.76 V (11.2%)1693.4 WDrop/Amp High
12 AWG3.31 mm²20 A20.48 V (4.27%)459.5 V33.78 V (7.04%)1064.1 WDrop/Amp High
10 AWG5.26 mm²30 A12.89 V (2.68%)467.1 V21.26 V (4.43%)669.6 W✓ PASS (≤3%)
8 AWG8.37 mm²50 A8.1 V (1.69%)471.9 V13.36 V (2.78%)420.8 W✓ PASS (≤3%)
6 AWG13.3 mm²65 A5.1 V (1.06%)474.9 V8.41 V (1.75%)264.8 W✓ PASS (≤3%)
4 AWG21.15 mm²85 A3.21 V (0.67%)476.8 V5.29 V (1.1%)166.5 W✓ PASS (≤3%)
3 AWG26.67 mm²100 A2.54 V (0.53%)477.5 V4.19 V (0.87%)132.1 W✓ PASS (≤3%)
2 AWG33.62 mm²115 A2.02 V (0.42%)478.0 V3.33 V (0.69%)104.8 W✓ PASS (≤3%)
1 AWG42.41 mm²130 A1.6 V (0.33%)478.4 V2.64 V (0.55%)83.1 W✓ PASS (≤3%)
1/0 AWG53.49 mm²150 A1.27 V (0.26%)478.7 V2.09 V (0.44%)65.8 W✓ PASS (≤3%)
2/0 AWG67.43 mm²175 A1.01 V (0.21%)479.0 V1.66 V (0.35%)52.2 W✓ PASS (≤3%)
3/0 AWG85.01 mm²200 A0.8 V (0.17%)479.2 V1.32 V (0.27%)41.4 W✓ PASS (≤3%)
4/0 AWG107.2 mm²230 A0.63 V (0.13%)479.4 V1.04 V (0.22%)32.9 W✓ PASS (≤3%)
250 kcmil126.7 mm²255 A0.54 V (0.11%)479.5 V0.88 V (0.18%)27.8 W✓ PASS (≤3%)
300 kcmil152.0 mm²285 A0.45 V (0.09%)479.6 V0.74 V (0.15%)23.2 W✓ PASS (≤3%)
350 kcmil177.3 mm²310 A0.38 V (0.08%)479.6 V0.63 V (0.13%)19.9 W✓ PASS (≤3%)
400 kcmil202.7 mm²335 A0.33 V (0.07%)479.7 V0.55 V (0.11%)17.4 W✓ PASS (≤3%)
500 kcmil253.4 mm²380 A0.27 V (0.06%)479.7 V0.44 V (0.09%)13.9 W✓ PASS (≤3%)
600 kcmil304.0 mm²420 A0.22 V (0.05%)479.8 V0.37 V (0.08%)11.6 W✓ PASS (≤3%)
750 kcmil380.0 mm²475 A0.18 V (0.04%)479.8 V0.29 V (0.06%)9.3 W✓ PASS (≤3%)
1000 kcmil506.7 mm²545 A0.13 V (0.03%)479.9 V0.22 V (0.05%)7.0 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 30 amps at 200 feet (480V)?

To stay within the NEC recommended 3% maximum voltage drop for a 30A load over 200 feet one-way at 480V (3-Phase), you need 10 AWG copper wire. This produces a voltage drop of 12.89V (2.68%) and delivers 467.1V at the load.

What size aluminum wire is required for 30 amps at 200 feet?

Using aluminum conductors (75°C rating), you should use 8 AWG to maintain voltage drop at 13.36V (2.78%).

What breaker size is needed for a 30A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (30A × 1.25 = 37.5A), which corresponds to a standard 40A circuit breaker.