Transformers are a Source of Electricity.   Electricity always flows back to its Source.  

Many boats use the Shore Transformer for their source of power.    This works great as long as there are no faults on any circuit between or connected to the source.

Most electronic items leak a little bit of energy through their line filters, which dump transients to ground.    This little leakage is usually less than 3 milliamps and will return to the last transformer.   Yet only 6 milliamps is dangerous?

Safety and Reliability of any transformer sourced system is dependent on the integrity of every circuit connected to the same transformer.      Since Shorepower transformers often provide power to hundreds of boats with thousands of circuits,  independence from these vast and complex systems very desirable.

When you have your own transformer, you make your own electricity, which has many safety and reliability advantages



Everything between the closest transformer, and outlets on your boat, must be hard grounded.    This means there can be no switches and or other wise ways of breaking ground.   Ground must be continuous from the case of the transformer to every ground wire on your boat.   This is to insure that fault currents always have a way of tripping breakers in case of a power fault.    Ground Fault Currents can travel through the water, and through your boat,  in the event of a fault on any one’s shorepower connected boat.   A marina with high fault currents is known in California, as a hot marina.    In reality, marinas have hot-spots made by boats with significant ground faults.

Boats with hard grounded systems rely on the ground wire to carry all fault currents.    These boats are then dependent on the ground wire connection back to the transformer for safety purposes.    These circuits are subject to corrosion and movement and require constant maintenance to be kept update.

Without an isolation transformer and you travel to a marina that has reverse polarity, then your boat will not safely operate, and you could hurt yourself or damage equipment if you try.

The grounds of a boat without an isolation transformer are hard- tied to the grid, which every boat shares.    Since everything is hard wired together, and nothing can be isolated, it becomes very difficult to troubleshoot.    And your neighbors problems, then become yours.   Everyone shares everyone elses galvanic issues on boats that are hard ground wired together.     All connected underwater metals will corrode according to their nobility.

When you don’t have an isolation transformer, then the sum total of all ground faults will be what is presented to the master breaker.    This can be enough to create nuisance tripping in marinas that have ELCI breakers installed.    ELCI breakers have a trip fault of 30 milliamps through the ground wire and are not enough protection from Electric Shock Drowning in Fresh Water.

Shorepower systems in marinas are very complex systems that are not desirable to be directly hooked into your electrical system, especially if you are going to use it for a high power battery charger.



An Isolation transformer isolates the power, and the ground wire.    The Isolation Transformer is a permanent fix many issues with shore-power.

You make your own power.    Fault Currents or overload currents never leave your boat, so swimmers are protected.   You control your own power.    When you hook into the marina, you have zero fault currents to add to the marina system, – your boat has become electrically independent of the grid.      Your boat will not nuisance trip an ELCI breaker, because it can’t.    This results in very dependable, reliable power for your boat.    Isolation transformers have high levels of protection from reverse polarity situation and therefore are exempt from reverse polarity indication.

Galvanic Isolators can be removed from the system.    Isolation Transformers remove the problem that the Galvanic Isolator is trying to fix.

The electrical power on your boat is clean, and yours and yours alone.   An Isolation transformer guarantees that your boat will not put dangerous AC currents in the water, and will be immune from other boats systems.

You protect your self and the swimmers around your boat from any fault in the water.    You can make every outlet or appliance protected by GFCI.

Transformers can be wired for 120 or 240 input for travel to foreign countries.

You declare electrical independence from the grid when you add an isolation transformer.

Independence, in the electrical world is a very good thing.    It allows easy interpretation of the system while adding electrical safety.

An Isolation transformer is an elegant piece of equipment to have aboard a boat.   It adds a considerable measure of safety, and protects your investment.


Isolation Transformer

  • Enables the use of a GFCI protected Shorepower Cord
  • Zero Leakage Current Eliminates Nuisance Tripping in Upstream Shorepower Breaker and Pedestal Breaker
  • Continues to function when Shorepower has Reverse Polarity
  • Eliminates the need for Reverse Polarity Indicator
  • Eliminates the need for a Galvanic Isolator
  • Cleans AC power from Transients caused by neighboring boats
  • Protects electronics, chargers and inverter-chargers by cleaning AC power
  • Prevents Ground Fault Current on all AC circuit getting into the water surrounding the boat
  • Prevents Electric Shock Drowning in Fresh and Brackish water
  • Prevents Corrosion of Underwater Metals in Brackish or Salt Water
  • Extends the Life of Zincs
  • Isolates Line, Neutral and Ground Wires on the boat, from Shorepower Line, Neutral and Ground.
  • Can be wired with 120 VAC input and Split Phase 120/240 VAC Output to increase charger output.
  • Can be wired with 240 single phase input for cruising with additional switch and inlet.
  • Will not change the frequency of the Power.   If plugging into 50 HZ, be sure that all appliances are capable of running of 50 HZ power.
  • Weight: 60 lbs.
  • Mount on a sturdy platform, low in the boat, in a dry, ventilated compartment.