Dock safety remains an issue at the Lake of the Ozarks. Over the last 10 years, local fire marshals have required electricians to install metal outlet receptacles and a grounding system on our docks. Both systems are failing.
Case in point: Recently in Sunrise Beach, we had a 30-year-old dock with romex wiring lying on the frame and recently installed 3-year-old grounding system. No problems with the romex. All wiring was correct.
This system sent 72 volts to the water and only 40 volts to the ground rod.
The problem, a 30-year-old three-way switch shorted to ground through the metal receptacle, to the frame then to ground.
Except the grounding system was compromised by corroded connections from galvanic reaction that occurs when dissimilar metals contact each other.
This goes on 24/7 and is accelerated by high humidity until the connections fail. If this dock is average, with five years, all of the grounded docks will fail to ground out a short from a metal receptacle.
Conducting electrical power to the frame is what causes people to die.
The solution is very simple: Require your electrician to wire your dock using only plastic components.
Use only PVC conduant, plastic receptacle boxes on all outlets, switched and light fixtures. McGill makes such light fixtures and are available at CED supply and Butler supply locally.
Use a GFI breaker at the post. A ground rod is optional because they will fail anyway. Using all plastic components will ensure you and your grandchildren's safety.