Stray Voltage – A Growing Issue On The Farm

By James Donahue

Sick and dying livestock on dairy farms has been, perhaps, an early warning sign that something is going wrong with the aging power lines across the United States. The problem – identified as stray voltage – has prompted at least six lawsuits by dairy farms against local electric companies.

The farmers are claiming that stray voltage from overloaded and outdated power lines passing over and servicing their land is killing their cattle. Xcel Energy, one of the power companies named in litigation in Minnesota, argues that the deaths could be blamed on other factors. A 1996 advisory report to the Minnesota Public Utilities Commission found “no credible scientific evidence” that ground current can sicken dairy herds.

Stray voltage has been suspected as the cause of the deaths since the early 1980s, although in the beginning, the issue was whether there was such a thing as stray voltage, and later, once it was proven, the question was how much voltage is harmful.

Since then, however, the incidence of cattle deaths from suspected overladen power lines has grown. And Consolidated Edison recorded 1,214 cases of stray voltage in New York City in 2005. Among the deaths believed caused by stray voltage was a woman who stepped on a metal plate, and a dog that perished while standing on wet concrete.

The dairy farmers claim there are two kinds of stray voltage that are giving them problems. One is extra spillover from the overtaxed power lines that feed into the farm’s electrical system. The other is ground current. The theory is that electricity jumps from the overloaded lines and follows a course in the ground to complete a circuit. This happens when the line is in poor repair or there is a lack of capacity. The power finds the ground through the farm grounding rods.

Some estimate that two-thirds of the current is returning that way. And when a dairy farm is in its path, all the the mud, the metal equipment, water troughs and the cattle become part of the circuit. The shocks that hit the cattle don’t kill them immediately, but they make them sick, and eventually cause them to collapse.

This is why stray voltage has been so difficult for farmers and even the electric companies to identify and prove. The cattle show all of the symptoms of a disease, but one that is an unknown mystery.

Thus the problem of 70 to 100-year-old electric distribution lines that need to be replaced and updated is joining a long list of infrastructure issues breaking down all across America. Expect this problem to get much worse before something gets done about it.