A Boater’s Guide To AC Electrical Systems

Your boat’s electrical panelboard is the “heart” of the electrical system. Electric current created by a shore side power source or AC electrical generator is dis-tributed throughout the boat by “hot” wires or ungrounded conductors. These vary in size based on the job they must perform.

European boats are different. They’re typically fitted with a 30-milliamp trip device at the AC main panel, which provides “whole boat” protection. In my view, this is a safer approach. This 30-milliamp value is probably a fair compromise on a small boat with few AC systems on board.

After many decades of troubleshooting and repairing boat wiring issues, I’ve become pretty darn good at figuring things out. Today’s boat wiring is one of the most difficult problems you’ll run across due to requirements of the numerous accessories. For the last several weeks, I have been chasing a problem that has been causing me to lose sleep at night.

Marine Electrical Devices, and UL 1500, Ignition Protection Test For Marine Products, and the electrical system requirements for boats in Title 33 CFR 183.410(a). 11.4.20 Polarized system AC - A system in which the grounded and ungrounded conductors are connected in the same relation to terminals or leads on devices in the circuit.

The shore power cable and connection is the most easily overloaded point of wiring on the boat because it feeds all of the AC system including receptacle circuits. Every new appliance brought onboard can add a new load, and devices like electric grills, hair driers, air conditioners and space heaters are designed to use about 12 Amps each.

AC wiring for 110 volts usually has white for neutral, black for hot, and green for ground (220-volt AC lines have a second hot wire, ... (E-11) regarding boat wiring, with your safety the bottom line. The U.S. Coast Guard has requirements for electrical systems in Title 33, CFR 183 Subpart I, Section 183.

Even a seemingly simple boat wiring project often became much more complicated than its "on shore" equivalent for many reasons: The lack of boat wiring diagrams. The regular use of non-standard and non-traceable boat wire colors. Or, worse, the all-too-common practice of wiring an entire boat with only one color of marine electic wire.

It’s pretty standard in boat wiring to bypass the main battery switch for one thing: The boat’s bilge pump float switch. This way, even if your battery switch is off, if your boat starts filling with water the pump will still kick on. I’d rather have a dead battery than a swamped boat. Notice ...

This is something to be aware of, but the relevant ABYC standard only applies to wiring carrying 50 volts or more, so it is typically a problem with AC circuits on a boat, not your typical 12 volt DC wiring installation. In general, if three conductors are bundled, reduce maximum amperage by 30 percent.

Marine wire quality is important and our marine grade wire is designed specifically to survive the harsh marine environment. Our boat wire is fine stranded copper (Type III stranding) with each strand completely tin plated so tinned copper will resist corrosion and ensure safe and secure operation for many years to come.