According to multiple reports, most AC electrical fires occur at the boats shorepower inlet. To address this and other shortcomings of the standard twist-type boatside connection, SmartPlug Systems developed a new AC shorepower system that the company hopes will become the new marine standard.
Loose and corroded connections are most often the culprits when overheating occurs. Corrosion typically results when moisture gets in at the plug-inlet connection, while arcing-which in turn leads to pitting, scorching, and heat build-up-is partially due to the shape and small contact area of the connector pins.
SmartPlug engineers have devised a four-stage approach that addresses these issues and protects against overheating. The SmartPlug system can be retrofitted to an existing shorepower cords boat end. The new sleeve design and multi-point plug-to-receptacle locking system ensures that the body of the plug rather than the pins bears the weight or tension of the cord, reducing movement and loosening. To alleviate arcing and corrosion, the pin contact area is increased by more than 20 times a standard plug, and it is protected by three weatherproof seals.
The SmartPlug inlet also features a built-in thermal overload sensor that automatically cuts power when the connector reaches 200 degrees. Power is restored when the temperature drops to 120 degrees.
The SmartPlug is a well-built unit that carries a limited seven-year warranty. All external metals are marine-grade 316 stainless steel, the electrical pins are nickel-plated brass, and the plastics are made of UV- and heat-resistant Valox 553U resins.
The companys 30-amp inlet and connector retrofit kit sells for $225-a bit expensive, in our opinion, but reasonable when compared to the $100-$200 cost of a standard outlet and plug, particularly considering the added safety and waterproofing features of the SmartPlug. The SmartPlug meets rigorous Underwriters Laboratory Marine requirements (as tested by IMANNA Labs) and the American Boat and Yacht Councils E-11 safety standard, according to the company. It also is Coast Guard compliant.
To retrofit an existing, standard shorepower cord, users can simply cut off the existing boatside plug and wire the new SmartPlug following the provided directions. The SmartPlug inlet is designed to fit the same opening and screw holes of the legacy twist-lock inlet with little or no modification required.
Testers found the directions clear and easy to follow, and the only tools needed for the project were a screwdriver and a knife or wirestrippers. Installing the adaptor kit was a relatively quick and painless job.
The companys website also offers a comprehensive installation video: www.smartplug.com/learn.html.
Pros and cons
Having to line up the pins on a standard twist-lock connector can be a pain-its a minor pain, but a pain nonetheless-particularly at night when the boat is docked in some unlit portion of a marina. The straight-pin design of the SmartPlug eliminates this annoyance. All you have to do is push in the plug (which only goes in one way) until the side levers sound an audible “click,” and then snap the locking cap down to lock it in place.
The most obvious drawback of the SmartPlug is that a twist-type plug (or adaptor) is still required to connect to shorepower at the shore side. Although the SmartPlug isn’t a clean break from the twist-type connections, it does provide some benefits, including thermal protection and increased weatherproofing at the boat end of the setup.
From a design standpoint, testers liked the clever internal cord-strain relief clamp, but we had a minor issue with the poor grip provided by the SmartPlug when unplugging. The length of the plug body and placement of the release tabs means that hands, particularly wet ones, tend to slide down to the cable when pulling unless care is used.
The SmartPlug is well-made and offers several improvements over the standard twist-type AC plug; however, attempting to replace a system so firmly entrenched in the industry is a tall order for any company. The additional safety features and increased weatherproofing alone will likely provide many sailors enough incentive to upgrade, but its too early in the game to predict how well it will ultimately be embraced by the boating and marina community.