GFCI Danger! Something we all need to know!

In this past week, I was called out to a boat for an "electrical glitch" and found this, a little more than a glitch:

What the photo does not show is the fire and smoke that had also filled the boat.  This boat owner was extremely lucky, we were able to extinguish the fire in a matter of minutes and save the boat.  It would have otherwise surely destroyed the boat.

A Ground Fault Circuit Interrupter (GFCI) is an important part of our house and boat. It protects us against electrical shock.  A GFCI monitors the amount of current flowing from hot to neutral.  A GFCI can detect how much current is flowing to the receptacle on the "hot," or black wire, and then looks for the exact same amount flowing back on the "neutral," or white wire.  If there is any imbalance, it trips the circuit.  It is able to sense a mismatch as small as 4 or 5 milliamps, and it can react as quickly as one-thirtieth of a second.  This is great for protecting us against electrical shock, however what happens when we add saltwater or humid saltwater-rich air?  Corrosion and potential for fire.

In the photos above, the GFCI outlet was installed from the factory and installed on the vessel's exterior.  The manufacturer is a very prestigious, high-end producer of motor yachts known for building some of the best yachts in the world.  There were three outlets on the outside of the boat; each was installed in the same manner.  The manufacturer used a water-resistant cover that was spring loaded to help keep the elements out of the circuit; however, a number of errors were made in the installation.  First: they used a household approved outlet, something that can be obtained from a hardware store, NOT a marine-grade outlet.  The second is that the outlet was installed without using an electrical box.  Third, they installed this outlet exterior of the ship's cabin.  I would like to take a moment to explain each of these errors and hope to show you why these were bad decisions:

1. Marine grade GFCI - All of the copper connections inside this device are tinned to help stop corrosion.  The household grade GFCIs will corrode, giving the potential for electrical arching.  When this arching occurs, it creates enough heat to start a fire.
2. Electrical boxes have three functions: 1.) to prevent accidental electrical shock 2.) to keep the elements out and 3.) to minimize the amount of oxygen should a fire occur.  Without an electrical box, salt air was able to attack the GFCI and when the fire occurred, it gave the fire unlimited amounts of oxygen to allow it to expand unchecked.  If a fire occurs inside an electrical box, it will be starved for oxygen, extinguishing itself rather quickly.
3. Using a GFCI on an external circuit is simply asking for trouble.  The elements will get to the device easier and more rapidly.  It would be better to install the GFCI in a location inside the cabin and protect the exterior outlet downstream.  By doing so, not only do you take the GFCI out of the elements but you also protect all of the wiring that goes to the outlet.

In the case above, we had contacted the manufacturer to discuss the problem and they  agreed that this is not the first case brought to their attention.  They advised us that all of the exterior GFCIs must be removed and protected from inside the ship's cabin, preferably near the electrical panel where the power begins.

I am a firm believer in GFCI circuits, they save lives!  Caution needs to be taken where they are used and how they are wired.  No boater wants to hear of this happening to any boat.  Post any of your questions here, I would be glad to answer them.