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

10 Amp Wire Size at 275 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 10 A load over a 275 ft (83.8 m) one-way run.

Copper Wire (≤3% Drop)10 AWG5.26 mm² · Drop: 2.46%
Aluminum Wire (≤3% Drop)8 AWGDrop: 6.12V (2.55%)
Voltage at Load End234.1 VLoss: 5.91 V (102.3 W)
Power & Breaker (125%)4.16 kW13A Breaker Recommended

All AWG & kcmil Wire Gauges for 10 Amps at 275 Feet (240V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A14.94 V (6.22%)225.1 V24.64 V (10.27%)258.7 WDrop/Amp High
12 AWG3.31 mm²20 A9.39 V (3.91%)230.6 V15.48 V (6.45%)162.6 W~ ≤5%
10 AWG5.26 mm²30 A5.91 V (2.46%)234.1 V9.74 V (4.06%)102.3 W✓ PASS (≤3%)
8 AWG8.37 mm²50 A3.71 V (1.55%)236.3 V6.12 V (2.55%)64.3 W✓ PASS (≤3%)
6 AWG13.3 mm²65 A2.34 V (0.97%)237.7 V3.85 V (1.61%)40.5 W✓ PASS (≤3%)
4 AWG21.15 mm²85 A1.47 V (0.61%)238.5 V2.42 V (1.01%)25.4 W✓ PASS (≤3%)
3 AWG26.67 mm²100 A1.16 V (0.49%)238.8 V1.92 V (0.8%)20.2 W✓ PASS (≤3%)
2 AWG33.62 mm²115 A0.92 V (0.39%)239.1 V1.52 V (0.64%)16.0 W✓ PASS (≤3%)
1 AWG42.41 mm²130 A0.73 V (0.31%)239.3 V1.21 V (0.5%)12.7 W✓ PASS (≤3%)
1/0 AWG53.49 mm²150 A0.58 V (0.24%)239.4 V0.96 V (0.4%)10.1 W✓ PASS (≤3%)
2/0 AWG67.43 mm²175 A0.46 V (0.19%)239.5 V0.76 V (0.32%)8.0 W✓ PASS (≤3%)
3/0 AWG85.01 mm²200 A0.37 V (0.15%)239.6 V0.6 V (0.25%)6.3 W✓ PASS (≤3%)
4/0 AWG107.2 mm²230 A0.29 V (0.12%)239.7 V0.48 V (0.2%)5.0 W✓ PASS (≤3%)
250 kcmil126.7 mm²255 A0.25 V (0.1%)239.8 V0.4 V (0.17%)4.2 W✓ PASS (≤3%)
300 kcmil152.0 mm²285 A0.2 V (0.09%)239.8 V0.34 V (0.14%)3.5 W✓ PASS (≤3%)
350 kcmil177.3 mm²310 A0.18 V (0.07%)239.8 V0.29 V (0.12%)3.0 W✓ PASS (≤3%)
400 kcmil202.7 mm²335 A0.15 V (0.06%)239.8 V0.25 V (0.11%)2.7 W✓ PASS (≤3%)
500 kcmil253.4 mm²380 A0.12 V (0.05%)239.9 V0.2 V (0.08%)2.1 W✓ PASS (≤3%)
600 kcmil304.0 mm²420 A0.1 V (0.04%)239.9 V0.17 V (0.07%)1.8 W✓ PASS (≤3%)
750 kcmil380.0 mm²475 A0.08 V (0.03%)239.9 V0.13 V (0.06%)1.4 W✓ PASS (≤3%)
1000 kcmil506.7 mm²545 A0.06 V (0.03%)239.9 V0.1 V (0.04%)1.1 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 10 amps at 275 feet (240V)?

To stay within the NEC recommended 3% maximum voltage drop for a 10A load over 275 feet one-way at 240V (3-Phase), you need 10 AWG copper wire. This produces a voltage drop of 5.91V (2.46%) and delivers 234.1V at the load.

What size aluminum wire is required for 10 amps at 275 feet?

Using aluminum conductors (75°C rating), you should use 8 AWG to maintain voltage drop at 6.12V (2.55%).

What breaker size is needed for a 10A continuous load?

Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (10A × 1.25 = 12.5A), which corresponds to a standard 13A circuit breaker.