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

110 Amp Wire Size at 250 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 110 A load over a 250 ft (76.2 m) one-way run.

Copper Wire (≤3% Drop)2 AWG33.62 mm² · Drop: 1.93%
Aluminum Wire (≤3% Drop)1/0 AWGDrop: 9.58V (2.0%)
Voltage at Load End470.8 VLoss: 9.24 V (1760.7 W)
Power & Breaker (125%)91.45 kW150A Breaker Recommended

All AWG & kcmil Wire Gauges for 110 Amps at 250 Feet (480V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A149.37 V (31.12%)330.6 V246.39 V (51.33%)28458.5 WDrop/Amp High
12 AWG3.31 mm²20 A93.86 V (19.55%)386.1 V154.83 V (32.26%)17883.3 WDrop/Amp High
10 AWG5.26 mm²30 A59.07 V (12.31%)420.9 V97.43 V (20.3%)11253.6 WDrop/Amp High
8 AWG8.37 mm²50 A37.12 V (7.73%)442.9 V61.23 V (12.76%)7072.1 WDrop/Amp High
6 AWG13.3 mm²65 A23.36 V (4.87%)456.6 V38.53 V (8.03%)4450.7 WDrop/Amp High
4 AWG21.15 mm²85 A14.69 V (3.06%)465.3 V24.23 V (5.05%)2798.8 WDrop/Amp High
3 AWG26.67 mm²100 A11.65 V (2.43%)468.4 V19.22 V (4.0%)2219.5 WDrop/Amp High
2 AWG33.62 mm²115 A9.24 V (1.93%)470.8 V15.24 V (3.18%)1760.7 W✓ PASS (≤3%)
1 AWG42.41 mm²130 A7.33 V (1.53%)472.7 V12.08 V (2.52%)1395.7 W✓ PASS (≤3%)
1/0 AWG53.49 mm²150 A5.81 V (1.21%)474.2 V9.58 V (2.0%)1106.6 W✓ PASS (≤3%)
2/0 AWG67.43 mm²175 A4.61 V (0.96%)475.4 V7.6 V (1.58%)877.9 W✓ PASS (≤3%)
3/0 AWG85.01 mm²200 A3.65 V (0.76%)476.3 V6.03 V (1.26%)696.3 W✓ PASS (≤3%)
4/0 AWG107.2 mm²230 A2.9 V (0.6%)477.1 V4.78 V (1.0%)552.2 W✓ PASS (≤3%)
250 kcmil126.7 mm²255 A2.45 V (0.51%)477.5 V4.04 V (0.84%)467.2 W✓ PASS (≤3%)
300 kcmil152.0 mm²285 A2.04 V (0.43%)478.0 V3.37 V (0.7%)389.4 W✓ PASS (≤3%)
350 kcmil177.3 mm²310 A1.75 V (0.37%)478.2 V2.89 V (0.6%)333.9 W✓ PASS (≤3%)
400 kcmil202.7 mm²335 A1.53 V (0.32%)478.5 V2.53 V (0.53%)292.0 W✓ PASS (≤3%)
500 kcmil253.4 mm²380 A1.23 V (0.26%)478.8 V2.02 V (0.42%)233.6 W✓ PASS (≤3%)
600 kcmil304.0 mm²420 A1.02 V (0.21%)479.0 V1.69 V (0.35%)194.7 W✓ PASS (≤3%)
750 kcmil380.0 mm²475 A0.82 V (0.17%)479.2 V1.35 V (0.28%)155.8 W✓ PASS (≤3%)
1000 kcmil506.7 mm²545 A0.61 V (0.13%)479.4 V1.01 V (0.21%)116.8 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 110 amps at 250 feet (480V)?

To stay within the NEC recommended 3% maximum voltage drop for a 110A load over 250 feet one-way at 480V (3-Phase), you need 2 AWG copper wire. This produces a voltage drop of 9.24V (1.93%) and delivers 470.8V at the load.

What size aluminum wire is required for 110 amps at 250 feet?

Using aluminum conductors (75°C rating), you should use 1/0 AWG to maintain voltage drop at 9.58V (2.0%).

What breaker size is needed for a 110A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (110A × 1.25 = 137.5A), which corresponds to a standard 150A circuit breaker.