5 Amp Wire Size at 225 Feet (12V DC (Solar / Automotive / Marine))
Complete conductor sizing, Ohm's law voltage drop, $I^2R$ line power loss, and circuit breaker specification for a 5 A load over a 225 ft (68.6 m) one-way run.
Copper Wire (≤3% Drop)1 AWG42.41 mm² · Drop: 2.88%
Aluminum Wire (≤3% Drop)2/0 AWGDrop: 0.36V (2.99%)
Voltage at Load End11.7 VLoss: 0.35 V (1.7 W)
Power & Breaker (125%)0.06 kW10A Breaker Recommended
All AWG & kcmil Wire Gauges for 5 Amps at 225 Feet (12V)
| Wire Gauge | Metric Area | NEC 75°C Cu Ampacity | Copper Voltage Drop | Load Voltage | Aluminum Drop | Line Loss ($I^2R$) | NEC Status |
|---|---|---|---|---|---|---|---|
| 14 AWG | 2.08 mm² | 15 A | 7.06 V (58.8%) | 4.9 V | 11.64 V (96.99%) | 35.3 W | Drop/Amp High |
| 12 AWG | 3.31 mm² | 20 A | 4.43 V (36.95%) | 7.6 V | 7.31 V (60.95%) | 22.2 W | Drop/Amp High |
| 10 AWG | 5.26 mm² | 30 A | 2.79 V (23.25%) | 9.2 V | 4.6 V (38.35%) | 14.0 W | Drop/Amp High |
| 8 AWG | 8.37 mm² | 50 A | 1.75 V (14.61%) | 10.2 V | 2.89 V (24.1%) | 8.8 W | Drop/Amp High |
| 6 AWG | 13.3 mm² | 65 A | 1.1 V (9.2%) | 10.9 V | 1.82 V (15.17%) | 5.5 W | Drop/Amp High |
| 4 AWG | 21.15 mm² | 85 A | 0.69 V (5.78%) | 11.3 V | 1.14 V (9.54%) | 3.5 W | Drop/Amp High |
| 3 AWG | 26.67 mm² | 100 A | 0.55 V (4.59%) | 11.4 V | 0.91 V (7.56%) | 2.8 W | ~ ≤5% |
| 2 AWG | 33.62 mm² | 115 A | 0.44 V (3.64%) | 11.6 V | 0.72 V (6.0%) | 2.2 W | ~ ≤5% |
| 1 AWG | 42.41 mm² | 130 A | 0.35 V (2.88%) | 11.7 V | 0.57 V (4.76%) | 1.7 W | ✓ PASS (≤3%) |
| 1/0 AWG | 53.49 mm² | 150 A | 0.27 V (2.29%) | 11.7 V | 0.45 V (3.77%) | 1.4 W | ✓ PASS (≤3%) |
| 2/0 AWG | 67.43 mm² | 175 A | 0.22 V (1.81%) | 11.8 V | 0.36 V (2.99%) | 1.1 W | ✓ PASS (≤3%) |
| 3/0 AWG | 85.01 mm² | 200 A | 0.17 V (1.44%) | 11.8 V | 0.28 V (2.37%) | 0.9 W | ✓ PASS (≤3%) |
| 4/0 AWG | 107.2 mm² | 230 A | 0.14 V (1.14%) | 11.9 V | 0.23 V (1.88%) | 0.7 W | ✓ PASS (≤3%) |
| 250 kcmil | 126.7 mm² | 255 A | 0.12 V (0.97%) | 11.9 V | 0.19 V (1.59%) | 0.6 W | ✓ PASS (≤3%) |
| 300 kcmil | 152.0 mm² | 285 A | 0.1 V (0.8%) | 11.9 V | 0.16 V (1.33%) | 0.5 W | ✓ PASS (≤3%) |
| 350 kcmil | 177.3 mm² | 310 A | 0.08 V (0.69%) | 11.9 V | 0.14 V (1.14%) | 0.4 W | ✓ PASS (≤3%) |
| 400 kcmil | 202.7 mm² | 335 A | 0.07 V (0.6%) | 11.9 V | 0.12 V (1.0%) | 0.4 W | ✓ PASS (≤3%) |
| 500 kcmil | 253.4 mm² | 380 A | 0.06 V (0.48%) | 11.9 V | 0.1 V (0.8%) | 0.3 W | ✓ PASS (≤3%) |
| 600 kcmil | 304.0 mm² | 420 A | 0.05 V (0.4%) | 12.0 V | 0.08 V (0.66%) | 0.2 W | ✓ PASS (≤3%) |
| 750 kcmil | 380.0 mm² | 475 A | 0.04 V (0.32%) | 12.0 V | 0.06 V (0.53%) | 0.2 W | ✓ PASS (≤3%) |
| 1000 kcmil | 506.7 mm² | 545 A | 0.03 V (0.24%) | 12.0 V | 0.05 V (0.4%) | 0.1 W | ✓ PASS (≤3%) |
Frequently Asked Engineering Questions
What size copper wire do I need for 5 amps at 225 feet (12V)?
To stay within the NEC recommended 3% maximum voltage drop for a 5A load over 225 feet one-way at 12V (DC), you need 1 AWG copper wire. This produces a voltage drop of 0.35V (2.88%) and delivers 11.7V at the load.
What size aluminum wire is required for 5 amps at 225 feet?
Using aluminum conductors (75°C rating), you should use 2/0 AWG to maintain voltage drop at 0.36V (2.99%).
What breaker size is needed for a 5A continuous load?
Under NEC 210.20(A), continuous loads require a circuit breaker rated at 125% of the continuous current (5A × 1.25 = 6.2A), which corresponds to a standard 10A circuit breaker.
Compare Other Distances & Amperages
5 Amp Wire Size by Distance (12V)
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