Ground Fault Shore Power

The National Electrical Code has added a section requiring new or remodeled marine shore power pedestals to be equipped with a ground fault sensor. This is great from a safety standpoint, but it creates problems for many boats.

Officially called Ground-Fault Protection of Equipment (GFPE), but are also referred to as ELCI or GFI, each having the same purpose but with slightly different thresholds. These circuit breakers not only trip to limit amps, but also monitors the neutral wire to ensure the same amount of electricity returns through the neutral as is being used by the hot (Line) wire(s). any differential indicates an electrical leak.,

Counterintuitive is the fact that the AC ground wire in terrestrial home systems is connected to the AC neutral wire at the main breaker panel (Green and white are connected). This connection manages any electrical leaks from neutral to ground by using stakes pounded, into the ground, providing a path for stray electricity that minimizes a shock hazard. On a boat, the neutral and ground can not be connected so without measuring this electrical differential, it is possible to energize the water around your boat with AC voltage through your bonding system. The electricity is always trying to find a preferable ground source and could electrocute a swimmer.

Because there are some unavoidable electrical leaks, the national electrical code excludes appliances like refrigerators and HVAC systems from GFI Requirements, but on boats, the ground fault sensor monitors everything on that vessel. Transformers, galvanization isolators, inverters, chargers, HVAC systems, and generators can all create issues, and the immediate or intermittent tripping of these breakers makes it very difficult to isolate and identify the issue. Further complicating things are the modifications made over the years with splices and exposed wires that could be anywhere.

Furthering the frustration is that many boats are not even aware that there is an issue until they first go to a marina with GFPE pedestals. They won't be able to use that marina's shore power until the issue is found and fixed. One way to bypass the problem is to disconnect the main ground, which is extremely dangerous because we know there is a leak waiting to electrocute someone.

Here at 12v Marine, we have test equipment to verify your boat will not trip a GFPE and the skill to locate and address any problems, so if headed south where these pedestals are common, give us a call and we can test your vessel.