Shore Power Voltage Drop & Chord Sizing Calculator

                Shore Power Voltage Drop Calculator
                REF: EN-702-ELEC

                Ensure your vessel gets safe and sufficient power at the dock. Use this calculator to determine the voltage drop across your shore power cord. Excessive voltage drop can damage sensitive onboard electronics, air conditioners, and motors.
            
                INPUT PARAMETERS

                    > SOURCE_VOLTAGE [V]
                    
                    Dock pedestal voltage
                
                    > LOAD_CURRENT [AMPS]
                    
                    Max continuous draw
                
                    > CABLE_LENGTH [FT]
                    
                    Distance from pedestal to boat
                
                    > CABLE_GAUGE [AWG]
                    
                    Wire thickness
                
> VOLTAGE_DROP_%

                0.0 %
            
ACTUAL DROP
0.0 V
END VOLTAGE
0.0 V

                STATUS
            
                Why Voltage Drop Matters
                When electricity travels through a wire, the resistance of the copper wire causes a loss of voltage over distance. If you use a shore power cord that is too long or too thin (wrong AWG) for the amount of current your boat draws, the voltage arriving at your main panel will be significantly lower than what the dock pedestal outputs.
            
ABYC Standards for Marine Wiring:3% Maximum Drop (Critical Circuits): For panel feeders, bilge blowers, and sensitive electronics, the ABYC strictly recommends keeping the voltage drop under 3%. Since shore power feeds your entire panel, 3% is the gold standard.
10% Maximum Drop (Non-Critical): For general lighting or non-essential systems, up to a 10% drop is acceptable, but this should be avoided for primary shore power cords.
The Danger of Low Voltage: Electric motors (like air conditioning compressors and refrigeration pumps) draw more amps when voltage drops to compensate for the lost power. This excess current generates heat and can cause premature motor failure or trip breakers.

                Pro Tip: If your regular slip is far from the pedestal and requires two 50ft cords daisy-chained together, seriously consider upgrading to a heavier gauge wire (like moving from 10 AWG to 8 AWG for a 30A circuit) to safely handle the 100ft run without extreme voltage loss.