Introduction to Blue Sea Systems' New Online DC Circuit Wizard

April, 16 2007

Blue Sea Systems’ DC Circuit Wizard simplifies the calculations necessary to choose appropriate DC circuit protection and wire size. The DC Circuit Wizard is available at It offers choices for circuit protection and the correct wire gauge.

DC Wire and Circuit Protection Selection

Enter information about the boat’s electrical system.

1.       DC Wire Selection

  • Information required to meet ABYC Standards—based on guidelines in ABYC E-11.
  • Additional derating factors—factors not considered in ABYC Standards when determining wire size. Blue Sea Systems' engineers have identified additional derating factors from experience in the field, and by experimenting in the laboratory, that can significantly influence the proper wire size required in a circuit.

2.       DC Circuit Protection Selection

  • Enter the Cold Cranking Amps (CCA) rating of battery.  
  • Choose Main or Branch circuit.

3.       Click Calculate

Wire Selection Results

The DC Circuit Wizard displays the recommended wire size. Notice that the recommended wire based on ABYC Standards and additional derating factors may be larger than the recommendation based on ABYC Standards alone.

Circuit Protection Results

The DC Circuit Wizard displays all of the acceptable fuse and circuit breaker options that meet the entered values. Choose a device according to its blow/trip value, AIC rating, cost, and preferences. For complete product information, click each option to link to the product page on Blue Sea Systems’ website.

The DC Circuit Wizard will be helpful for boat owners and boat builders to quickly perform calculations and eliminate many unsuitable circuit protection choices. The final decision on wire and circuit protection should come after a review based on additional sources such as the ABYC standards or the many books on the subject.

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