Voltage Drop Calculator | Marine Electrical System Tool
Calculate voltage drop in marine electrical circuits. Ensure proper wire sizing for your boat's electrical system.
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How to Use
- Enter the current draw in amperes
- Select the wire gauge (AWG)
- Enter the one-way wire length in meters
- Verify system voltage (default 12V)
- Click Calculate to get voltage drop
Note: For marine applications, voltage drop should be kept under 3% for critical circuits and under 10% for non-critical circuits.
Frequently Asked Questions
What is acceptable voltage drop on a boat?
AS/NZS 3004 recommends maximum 5% voltage drop for lighting circuits and 10% for motor circuits. For a 12V system, that is 0.6V and 1.2V respectively.
How do I reduce voltage drop on my boat?
Use larger wire gauge, shorten cable runs, or increase system voltage (e.g., 24V instead of 12V). Doubling voltage halves current and reduces voltage drop by 75%.
Why is voltage drop important for marine wiring?
Excessive voltage drop causes dim lights, slow motors, unreliable electronics, and wasted energy as heat in the wiring — which is also a fire risk on boats.