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Understanding Voltage Drops and How They Affect Your Onboard Systems


Voltage drop is a common issue in marine shore power systems, especially when using long shore cords or when marinas have aging infrastructure. Understanding how voltage drop works helps you avoid equipment problems and maintain safe electrical operation.

What is Voltage Drop?
Voltage drop occurs when the electrical potential decreases along the length of a conductor. As current travels through the shore cord, resistance causes a reduction in voltage at the point of use.

Why It Matters
Too much voltage drop can cause:

  • Equipment malfunction or failure
  • Dimming lights
  • Overheating of electrical components
  • Tripping of breakers

Marine standards like ABYC E-11 recommend limiting voltage drop to 3% for critical circuits and 10% maximumfor non-critical loads.

Factors That Influence Voltage Drop

  • Length of the shore cord: Longer cords create more resistance.
  • Cable size (AWG): Smaller wires have higher resistance.
  • Current draw: Higher loads increase voltage drop.
  • Connection quality: Corroded or loose plugs create additional resistance.

Example:
A 100-foot 2 AWG shore cord carrying 80 amps at 240V can have up to 6–8% voltage drop, depending on the load and connector condition.

How to Minimize Voltage Drop

  • Use the shortest practical shore cord.
  • Choose larger cable sizes (2 AWG or larger for high loads).
  • Keep all plugs and receptacles clean and corrosion-free.
  • Avoid coiling cables tightly, which can increase heat.

ANG Solutions
ANG marine power cords are built with heavy-duty copper conductors and low-resistance terminations to reduce voltage drop. Combined with ANG Shore Power Converters™, you can count on stable output voltage, even if shore power fluctuates.

Tip:
Always check voltage under load with a multimeter at the inlet to confirm performance.