Shore Power Safety: Cords, Inlets, Burned Plugs and Electric Shock Drowning

Turning power on and off at the right moment prevents arcing that burns plugs:

• To connect: turn off the boat's main shore power breaker and the pedestal breaker. Plug the cord into the boat first, then into the pedestal. Turn on the pedestal breaker, then the boat's main breaker.
• To disconnect: turn off the boat's main breaker and the pedestal breaker first. Unplug at the pedestal first, then at the boat. Put the weather cap back on the inlet.

Never plug or unplug a cord with power on, and never leave a live cord end lying on the dock or in the water.

With the cord unplugged at both ends, run it through your hands (with a dry rag) from end to end. Look for cuts, cracks, crushed or flattened spots, kinks, exposed inner wires, tape or splices, and soft or stiff areas that suggest heat. Any of these means replace the cord. Do not tape or repair a shore power cord.

Look closely at the pins, blades and the face of each end. Warning signs:

• Brown, black or blue discoloration
• Melted or blistered plastic
• Pitted, burned or green corroded contacts
• A loose or cracked locking ring or housing

BoatUS says burn marks on either end of the cord, or on the boat's receptacle, mean the cable, the boat's inlet, or the dock receptacle must be replaced. If one end of the cord is burned, assume what it was plugged into is damaged too, and have the inlet and pedestal checked.

Look at the inlet on the boat with the cord removed and power off. Check for the same burn and corrosion signs, cracks in the housing, a loose mounting, and a missing or broken weather cap. Look inside the boat behind the inlet only if it is easy to see without removing anything; discolored or melted wiring there is a call-a-pro-now item.

On a boat more than about 10 years old, the inlet deserves a pro's look even if the front looks fine. BoatUS's analysis of its fire claims found that most AC electrical fires start somewhere between the dock pedestal and the boat's inlet, and pinpointed the back of the inlet, where the boat's wiring attaches to the terminals, as a high-risk spot on older boats. Those terminals see water, vibration and corrosion, often next to things that burn easily. Its advice: if the inlet is original, have an electrician replace it, or at least pull it out and inspect the connections.

After the boat has been on shore power with a normal load (air conditioning, water heater or charger) for an hour or so, lightly touch the plug ends and the inlet with the back of your hand. Slightly warm can be normal; hot is not. If anything is hot, turn off the boat's main breaker and the pedestal breaker, let it cool, and have a marine electrician find the cause.

The cord should not hang by its plug or pull on the inlet. Leave a little slack for tide and movement, form a drip loop so water runs off before reaching the plug, and keep the cord out of the water and away from where it can be crushed or tripped over. Tighten the locking rings fully so the connection is snug and sealed.

• Use only marine shore power cords and listed marine adapters of the correct amp rating.
• Never use a household extension cord, a "cheater" adapter that skips the ground pin, or a homemade cord.
• Do not daisy-chain adapters. If the pedestal does not match your boat, ask the marina for a proper solution.

BoatUS also describes newer cord and inlet designs that seal better and reduce arcing; they are worth considering when you replace a cord, but the inlet change itself is a job for a pro.

If your panel has a reverse-polarity light or meter, check it right after you switch on. A reverse-polarity warning means turn everything off and unplug: the problem may be the boat, the cord or the pedestal. Tell the marina and do not use shore power until it is found.

If your boat has an ELCI main breaker, press its test button as the maker recommends (many say monthly). It should trip. Reset it. Test GFCI outlets aboard the same way. If an ELCI or GFCI trips by itself or trips repeatedly, do not keep resetting it: that is a fault that may be putting current where it should not be. Unplug and call an ABYC-certified electrician. If your older boat has no ELCI, ask an electrician about adding one.

Find your galvanic isolator (often near the inlet or main panel) and its remote monitor or status light if fitted. BoatUS recommends checking the unit and its connections for corrosion or damage at least once a year, and checking the monitor whenever you plug in and after nearby lightning. A fault light or a burned or corroded unit is for a pro. If your boat has a sterndrive or outboard and you use shore power but have no isolator, ask about one: Mercury recommends a galvanic isolator for boats on shore power to protect the drive from stray-current corrosion coming from the dock or nearby boats, and notes that this kind of corrosion damage is not covered by its warranty. Never disconnect the green ground wire to fix corrosion; that ground is what makes a fault trip the breaker instead of electrifying the boat and the water.

This test is non-invasive: the meter clamps around the outside of the cord. With the boat plugged in and every AC load aboard turned off, clamp the AC clamp meter around the whole shore power cord (all wires together). Because current going out and coming back should cancel, the reading should be essentially zero. Any steady reading means current is leaking somewhere, possibly into the water. Unplug and call an ABYC-certified electrician. Do not open the cord or clamp individual wires.

• No swimming within the marina or near docks and boats that use AC power. The ESDPA position is that it should be strictly prohibited.
• If you feel tingling in the water, shout a warning and swim away from the dock or boat, the way you came if you can, and do not grab metal ladders or docks.
• To help someone: reach, throw, don't go. Shut off power first if you can, use a boat hook, oar, line or life ring, and call 911. Rescuers who jump in often become victims. Start CPR if needed once the person is out.

Have an ABYC-certified marine electrician inspect the AC system, inlet and galvanic isolator periodically, after any burned plug or inlet, and before adding AC equipment. If you have a private dock, have the dock wiring inspected too. Ask your marina whether its docks have ground-fault protection. Record inspection dates and cord replacements in BoatMend.