POWERBOATER’S GUIDE TO ELECTRICAL SYSTEMS AC upgrades was to hire a licensed electrician to install the AC service. The problem was that this particular electrician, although probably a competent worker on shore-based systems, had no experience with marine electrical installations. Within months after a major refit to the boat, a fire broke out on board, and the boat burned to the waterline. The insurance investigation revealed that the fire was caused by the boat’s new AC shore-power system. This was a lesson hard-learned for the owner, and for the electrician! If you’re having an AC system professionally installed on your boat, ask your electrician if he or she has been certified by the ABYC to work on boats. If not, you might want to wait until they get certified, or simply look around for an electrician who has passed the ABYC certification program. Quality marine electricians are proud of this certification, and will always promote the fact that they are certified, so it shouldn’t be too hard to locate one in your area.
Basic AC Safety Rules I could easily fill up two or three pages with safety rules that all of us should observe when working with AC, but most of these rules are common sense. A case recently came to my attention where an electrician who had forgotten his wire stripper was removing insulation with his teeth. Everything went fine until he tried to strip the hot (black) wire while holding on to the bare end of the grounded (white) wire. He woke up in the hospital with a good part of his lips burned away. Therefore, one rule might be: Always turn off the power before you strip wire with your teeth. Another, older case suggests another rule: Never change a light bulb while standing in a bathtub full of water. There are lots more, but I have covered them all with rule number 10 below. Here are a few others that apply specifically to boats.
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certain equipment not to function, and at worst, it can destroy expensive gear. 3. When working on the AC system, disconnect the power at all times except when testing for voltage and amperage at points throughout the circuit. 4. Never work on a system with wet hands or feet or when any of the components are wet. 5. Make sure the boat is connected to a proper and tested ground, even when working with the power off. This means that whenever possible, you must avoid working on AC when the boat is at anchor or on a mooring. 6. Always wear rubber-soled shoes (deck shoes and running shoes are fine) when working on AC power. It’s also an excellent idea to wear rubber knee pads, because most of your work on a boat will be done while kneeling. 7. Never work on AC service with distractions such as a television or chatty friends present. 8. Ground-fault circuit interrupters (GFCIs) should be tested at least monthly to ensure proper function. 9. The common practice of clipping off the third prong (the grounding prong) of a three-pronged plug creates a real shock hazard on board a boat, and this should never be allowed. Any cords or equipment you have where this all-important terminal has been removed should have that third terminal replaced. 10. Avoid doing obviously dumb things (such as standing in water or putting hot wires in your mouth) when working with AC. Let’s take a more detailed look at specific system layout and the key standards as established by our friends at the ABYC.
1. Use only marine-grade products, wiring, terminal strips, and connectors on your boat.
Color Coding for AC Wiring
2. Observe polarity at all times. The orientation of the hot wire (also referred to as the ungrounded conductor) and the ground wire (the grounded conductor) and color-code matches are all very important. Reverse polarity can at the least cause
Unlike the DC systems already discussed, we will only be working with three colors for simple, smallboat AC wiring schemes. Larger boats using combined 120/240-volt systems use several additional colors for the extra legs of the circuitry that combine
