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

10 Amp Wire Size at 275 Feet (120V Single-Phase (US Standard Branch))

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)6 AWG13.3 mm² · Drop: 2.25%
Aluminum Wire (≤3% Drop)4 AWGDrop: 2.8V (2.33%)
Voltage at Load End117.3 VLoss: 2.7 V (27.0 W)
Power & Breaker (125%)1.2 kW13A Breaker Recommended

All AWG & kcmil Wire Gauges for 10 Amps at 275 Feet (120V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A17.25 V (14.37%)102.8 V28.45 V (23.71%)172.5 WDrop/Amp High
12 AWG3.31 mm²20 A10.84 V (9.03%)109.2 V17.88 V (14.9%)108.4 WDrop/Amp High
10 AWG5.26 mm²30 A6.82 V (5.68%)113.2 V11.25 V (9.38%)68.2 WDrop/Amp High
8 AWG8.37 mm²50 A4.29 V (3.57%)115.7 V7.07 V (5.89%)42.9 W~ ≤5%
6 AWG13.3 mm²65 A2.7 V (2.25%)117.3 V4.45 V (3.71%)27.0 W✓ PASS (≤3%)
4 AWG21.15 mm²85 A1.7 V (1.41%)118.3 V2.8 V (2.33%)17.0 W✓ PASS (≤3%)
3 AWG26.67 mm²100 A1.35 V (1.12%)118.7 V2.22 V (1.85%)13.5 W✓ PASS (≤3%)
2 AWG33.62 mm²115 A1.07 V (0.89%)118.9 V1.76 V (1.47%)10.7 W✓ PASS (≤3%)
1 AWG42.41 mm²130 A0.85 V (0.7%)119.2 V1.4 V (1.16%)8.5 W✓ PASS (≤3%)
1/0 AWG53.49 mm²150 A0.67 V (0.56%)119.3 V1.11 V (0.92%)6.7 W✓ PASS (≤3%)
2/0 AWG67.43 mm²175 A0.53 V (0.44%)119.5 V0.88 V (0.73%)5.3 W✓ PASS (≤3%)
3/0 AWG85.01 mm²200 A0.42 V (0.35%)119.6 V0.7 V (0.58%)4.2 W✓ PASS (≤3%)
4/0 AWG107.2 mm²230 A0.33 V (0.28%)119.7 V0.55 V (0.46%)3.3 W✓ PASS (≤3%)
250 kcmil126.7 mm²255 A0.28 V (0.24%)119.7 V0.47 V (0.39%)2.8 W✓ PASS (≤3%)
300 kcmil152.0 mm²285 A0.24 V (0.2%)119.8 V0.39 V (0.32%)2.4 W✓ PASS (≤3%)
350 kcmil177.3 mm²310 A0.2 V (0.17%)119.8 V0.33 V (0.28%)2.0 W✓ PASS (≤3%)
400 kcmil202.7 mm²335 A0.18 V (0.15%)119.8 V0.29 V (0.24%)1.8 W✓ PASS (≤3%)
500 kcmil253.4 mm²380 A0.14 V (0.12%)119.9 V0.23 V (0.19%)1.4 W✓ PASS (≤3%)
600 kcmil304.0 mm²420 A0.12 V (0.1%)119.9 V0.19 V (0.16%)1.2 W✓ PASS (≤3%)
750 kcmil380.0 mm²475 A0.09 V (0.08%)119.9 V0.16 V (0.13%)0.9 W✓ PASS (≤3%)
1000 kcmil506.7 mm²545 A0.07 V (0.06%)119.9 V0.12 V (0.1%)0.7 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 10 amps at 275 feet (120V)?

To stay within the NEC recommended 3% maximum voltage drop for a 10A load over 275 feet one-way at 120V (1-Phase), you need 6 AWG copper wire. This produces a voltage drop of 2.7V (2.25%) and delivers 117.3V at the load.

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

Using aluminum conductors (75°C rating), you should use 4 AWG to maintain voltage drop at 2.8V (2.33%).

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.