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Research likely finds cause of stray voltage at Smith Mountain Lake

Research likely finds cause of stray voltage at Smith Mountain Lake

Smith Mountain Lake

People on personal watercraft speed along Smith Mountain Lake on Saturday July 1, 2017 in Moneta, Va. 

When Jim Erler discovered small amounts of stray voltage in the water around his Huddleston dock late last year, he contacted an electrician to fix it. After spending $2,000 on work that didn’t solve the problem, he decided to find a solution on his own.

Erler, an electrical engineer and physicist, investigated the issue like any scientist would. He began taking measurements around his dock to find the exact cause — even connecting an oscilloscope to the electrical panel to track the varying voltages entering his home.

“I just became very curious,” Erler said.

Through his research, Erler said he has found that the source of his dock’s stray electricity comes from its ground wire from the house. It’s a problem with newer, as well as older, docks, and electricity can still be present in the water even if all the power to the house and dock is turned off.

The purpose of a ground wire is to provide an alternative pathway for electric current to travel if there is a problem. While the ground wire is required for safety, Erler said voltage can still be induced on the ground wire from several sources.

The voltage on the ground wire could come from normal power company operations or may be induced by something as small as an electronic device turning on in the home or even in a neighbor’s home, Erler said. And these voltages make their way to the dock and into the water.

In the dock checks he’s done over the past year, Neil Harrington of the Smith Mountain Lake Marine Volunteer Fire Department said stray voltage often enters the water through boat lifts. He said an underwater irrigation pump, extension cords, loose wires or any other metal in the water also can be a source for stray voltage.

While the stray voltage Erler has measured around his dock is usually fairly low, he has recorded intermittent levels of higher voltage on his oscilloscope that have concerned him.

“We have measured events that we know are lethal,” he said.

Harrington has spoken with local building inspectors about the issue. Erler said he has even spoken with a senior building inspector in Richmond in an effort to make changes to current electric code.

The issue, Erler said, extends far beyond Smith Mountain Lake. “There is a national problem here. We initially thought it was just a minor thing.”

During his research, Erler also contacted Underwriter Laboratories, an independent safety science company. He said experts there told him that they would never allow their families to swim from an electrically powered dock.

One fix Erler has found to stop a source of stray voltage is to disconnect the ground wire between the house and dock; however, he doesn’t recommend that since it currently is mandatory in building codes.

“It’s a complicated issue, and we are absolutely concerned about it,” said Will Goodwin, senior building inspector for Bedford County. All counties follow a statewide building code and inspectors are bound to enforce that code.

Goodwin said Virginia adopts its building code from the National Electric Code, and counties don’t have the ability to make changes.

While inspectors are bound by the state’s building code, Goodwin said they are still willing to help out if there is a problem. “If there is an issue, we will certainly go investigate it,” he said.

Erler said one way to protect individuals from some lethal levels of stray voltage around a dock is to make sure all dock breakers include a ground fault circuit interrupter or GFCI. They protect against ground faults by automatically shutting off the power when a leak of electric current is detected.

Current code requires that all breakers at docks include a GFCI at the power box, Erler said. Residents should test their GFCIs often to make sure it will turn the power off in case of a ground fault.

One of the best protections against electrical shock at a dock is to convert the power source to 12 volts DC. He said 12-volts could power almost anything used at a dock, including a boat lift.

Direct current at 12 volts is safer than 110 volts of alternating current that comes out of a normal power outlet, Erler said. A dock can be converted to run on a direct current for around $3,000, he said.

“All new docks should have direct current,” Erler said.

While Erler has found a major source of stray voltage around his dock, he is still researching to find out more. He said he would like to perform in-depth testing at other homes around the lake in an effort to better understand the problem.

He and Harrington would like to hold a public meeting in the future to discuss their findings.

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