Marine DC Wire Sizing Calculator
Calculate proper wire gauge for voltage drop and ampacity per ABYC E-11
Wire Requirements
Required Wire Size
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For Voltage Drop
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For Ampacity
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Calculated Voltage Drop
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Voltage at Load
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Power Loss in Wire
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Ampacity (Derated)
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Recommended Fuse
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Total Wire Needed
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ABYC Ampacity Table (105C Wire)
| AWG | Open Air | Bundled | Engine Room |
|---|---|---|---|
| 16 | 25A | 17A | 12A |
| 14 | 35A | 24A | 17A |
| 12 | 45A | 31A | 22A |
| 10 | 60A | 42A | 29A |
| 8 | 80A | 55A | 39A |
| 6 | 105A | 73A | 51A |
| 4 | 140A | 97A | 68A |
| 2 | 180A | 125A | 87A |
Marine Wiring Guidelines (ABYC E-11)
Wire Requirements
Use only marine-rated stranded copper wire (BC5W2 or equivalent). Solid wire is not permitted.
All connections must be within 7 feet of batteries or have proper fusing per ABYC E-11.
Use tinned marine wire in saltwater environments to prevent corrosion.
Voltage Drop Standards
3% maximum: Critical and general circuits (navigation, electronics, lighting).
10% maximum: Intermittent loads only (windlass, winches, thrusters).
Lower voltage drop = better efficiency and equipment performance.