WHAT SIZE WIRING SHOULD I USE WHEN INSTALLING MARINE ELECTRONICS?
Wire size for 12-volt DC applications depends on the current needed to operate the equipment being installed, the cable length, and possible voltage drop across the total cable run. Also consider the added current requirements for any electronics or electrical equipment you might be adding in the future.
You should follow the 3 and 10 percent rules when planning your wiring. Boat wiring standards specify that electronics, communications, navigation, safety and other critical equipment should have a 3 percent voltage drop loss factor to help ensure this equipment continues to be operational under allowable voltage drop conditions. A 10 percent voltage drop factor is used for noncritical electrical wiring such as interior lighting, entertainment electronics, windlass operation and other nonessential electrical gear.
Blue Sea Systems offers a current-versus-wire-size calculator at circuitwizard .bluesea.com to help you select the right wire size based on length, resistance, and the amount of current needed for your electronics, including the 3 and 10 percent rules. —Ken Englert