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

10 Amp Wire Size at 225 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 225 ft (68.6 m) one-way run.

Copper Wire (≤3% Drop)10 AWG5.26 mm² · Drop: 2.01%
Aluminum Wire (≤3% Drop)8 AWGDrop: 5.01V (2.09%)
Voltage at Load End235.2 VLoss: 4.83 V (83.7 W)
Power & Breaker (125%)4.16 kW13A Breaker Recommended

All AWG & kcmil Wire Gauges for 10 Amps at 225 Feet (240V)

Wire GaugeMetric AreaNEC 75°C Cu Ampacity Copper Voltage DropLoad VoltageAluminum DropLine Loss ($I^2R$)NEC Status
14 AWG2.08 mm²15 A12.22 V (5.09%)227.8 V20.16 V (8.4%)211.7 WDrop/Amp High
12 AWG3.31 mm²20 A7.68 V (3.2%)232.3 V12.67 V (5.28%)133.0 W~ ≤5%
10 AWG5.26 mm²30 A4.83 V (2.01%)235.2 V7.97 V (3.32%)83.7 W✓ PASS (≤3%)
8 AWG8.37 mm²50 A3.04 V (1.27%)237.0 V5.01 V (2.09%)52.6 W✓ PASS (≤3%)
6 AWG13.3 mm²65 A1.91 V (0.8%)238.1 V3.15 V (1.31%)33.1 W✓ PASS (≤3%)
4 AWG21.15 mm²85 A1.2 V (0.5%)238.8 V1.98 V (0.83%)20.8 W✓ PASS (≤3%)
3 AWG26.67 mm²100 A0.95 V (0.4%)239.0 V1.57 V (0.66%)16.5 W✓ PASS (≤3%)
2 AWG33.62 mm²115 A0.76 V (0.32%)239.2 V1.25 V (0.52%)13.1 W✓ PASS (≤3%)
1 AWG42.41 mm²130 A0.6 V (0.25%)239.4 V0.99 V (0.41%)10.4 W✓ PASS (≤3%)
1/0 AWG53.49 mm²150 A0.48 V (0.2%)239.5 V0.78 V (0.33%)8.2 W✓ PASS (≤3%)
2/0 AWG67.43 mm²175 A0.38 V (0.16%)239.6 V0.62 V (0.26%)6.5 W✓ PASS (≤3%)
3/0 AWG85.01 mm²200 A0.3 V (0.12%)239.7 V0.49 V (0.21%)5.2 W✓ PASS (≤3%)
4/0 AWG107.2 mm²230 A0.24 V (0.1%)239.8 V0.39 V (0.16%)4.1 W✓ PASS (≤3%)
250 kcmil126.7 mm²255 A0.2 V (0.08%)239.8 V0.33 V (0.14%)3.5 W✓ PASS (≤3%)
300 kcmil152.0 mm²285 A0.17 V (0.07%)239.8 V0.28 V (0.11%)2.9 W✓ PASS (≤3%)
350 kcmil177.3 mm²310 A0.14 V (0.06%)239.9 V0.24 V (0.1%)2.5 W✓ PASS (≤3%)
400 kcmil202.7 mm²335 A0.13 V (0.05%)239.9 V0.21 V (0.09%)2.2 W✓ PASS (≤3%)
500 kcmil253.4 mm²380 A0.1 V (0.04%)239.9 V0.17 V (0.07%)1.7 W✓ PASS (≤3%)
600 kcmil304.0 mm²420 A0.08 V (0.03%)239.9 V0.14 V (0.06%)1.4 W✓ PASS (≤3%)
750 kcmil380.0 mm²475 A0.07 V (0.03%)239.9 V0.11 V (0.05%)1.2 W✓ PASS (≤3%)
1000 kcmil506.7 mm²545 A0.05 V (0.02%)239.9 V0.08 V (0.03%)0.9 W✓ PASS (≤3%)

Frequently Asked Engineering Questions

What size copper wire do I need for 10 amps at 225 feet (240V)?

To stay within the NEC recommended 3% maximum voltage drop for a 10A load over 225 feet one-way at 240V (3-Phase), you need 10 AWG copper wire. This produces a voltage drop of 4.83V (2.01%) and delivers 235.2V at the load.

What size aluminum wire is required for 10 amps at 225 feet?

Using aluminum conductors (75°C rating), you should use 8 AWG to maintain voltage drop at 5.01V (2.09%).

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.