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

80 Amp Wire Size at 150 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 80 A load over a 150 ft (45.7 m) one-way run.

Copper Wire (≤3% Drop)4 AWG21.15 mm² · Drop: 1.34%
Aluminum Wire (≤3% Drop)2 AWGDrop: 6.65V (1.39%)
Voltage at Load End473.6 VLoss: 6.41 V (888.2 W)
Power & Breaker (125%)66.51 kW100A Breaker Recommended

All AWG & kcmil Wire Gauges for 80 Amps at 150 Feet (480V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A65.18 V (13.58%)414.8 V107.51 V (22.4%)9031.5 WDrop/Amp High
12 AWG3.31 mm²20 A40.96 V (8.53%)439.0 V67.56 V (14.08%)5675.4 WDrop/Amp High
10 AWG5.26 mm²30 A25.77 V (5.37%)454.2 V42.52 V (8.86%)3571.4 WDrop/Amp High
8 AWG8.37 mm²50 A16.2 V (3.37%)463.8 V26.72 V (5.57%)2244.4 WDrop/Amp High
6 AWG13.3 mm²65 A10.19 V (2.12%)469.8 V16.81 V (3.5%)1412.4 WDrop/Amp High
4 AWG21.15 mm²85 A6.41 V (1.34%)473.6 V10.57 V (2.2%)888.2 W✓ PASS (≤3%)
3 AWG26.67 mm²100 A5.08 V (1.06%)474.9 V8.39 V (1.75%)704.4 W✓ PASS (≤3%)
2 AWG33.62 mm²115 A4.03 V (0.84%)476.0 V6.65 V (1.39%)558.8 W✓ PASS (≤3%)
1 AWG42.41 mm²130 A3.2 V (0.67%)476.8 V5.27 V (1.1%)442.9 W✓ PASS (≤3%)
1/0 AWG53.49 mm²150 A2.53 V (0.53%)477.5 V4.18 V (0.87%)351.2 W✓ PASS (≤3%)
2/0 AWG67.43 mm²175 A2.01 V (0.42%)478.0 V3.32 V (0.69%)278.6 W✓ PASS (≤3%)
3/0 AWG85.01 mm²200 A1.59 V (0.33%)478.4 V2.63 V (0.55%)221.0 W✓ PASS (≤3%)
4/0 AWG107.2 mm²230 A1.26 V (0.26%)478.7 V2.09 V (0.43%)175.2 W✓ PASS (≤3%)
250 kcmil126.7 mm²255 A1.07 V (0.22%)478.9 V1.77 V (0.37%)148.3 W✓ PASS (≤3%)
300 kcmil152.0 mm²285 A0.89 V (0.19%)479.1 V1.47 V (0.31%)123.6 W✓ PASS (≤3%)
350 kcmil177.3 mm²310 A0.76 V (0.16%)479.2 V1.26 V (0.26%)106.0 W✓ PASS (≤3%)
400 kcmil202.7 mm²335 A0.67 V (0.14%)479.3 V1.1 V (0.23%)92.7 W✓ PASS (≤3%)
500 kcmil253.4 mm²380 A0.54 V (0.11%)479.5 V0.88 V (0.18%)74.1 W✓ PASS (≤3%)
600 kcmil304.0 mm²420 A0.45 V (0.09%)479.6 V0.74 V (0.15%)61.8 W✓ PASS (≤3%)
750 kcmil380.0 mm²475 A0.36 V (0.07%)479.6 V0.59 V (0.12%)49.4 W✓ PASS (≤3%)
1000 kcmil506.7 mm²545 A0.27 V (0.06%)479.7 V0.44 V (0.09%)37.1 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 80 amps at 150 feet (480V)?

To stay within the NEC recommended 3% maximum voltage drop for a 80A load over 150 feet one-way at 480V (3-Phase), you need 4 AWG copper wire. This produces a voltage drop of 6.41V (1.34%) and delivers 473.6V at the load.

What size aluminum wire is required for 80 amps at 150 feet?

Using aluminum conductors (75°C rating), you should use 2 AWG to maintain voltage drop at 6.65V (1.39%).

What breaker size is needed for a 80A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (80A × 1.25 = 100.0A), which corresponds to a standard 100A circuit breaker.