Pennsylvania zeroes in on stray voltage

CARLISLE, Pa. – Farmers and researchers alike have known since the 1960s that dairy cows can sometimes be shocked into refusing to be milked. But stray voltage is an elusive problem that has never been totally solved.

The Pennsylvania Grange is bringing the problem to the forefront again this year, after a Montgomery County farm supply technician’s stories caught the attention of former Pennsylvania Grange Grand Master Charlie Wismer.

The Pennsylvania Department of Agriculture has assembled a state task force to look at what the state should be doing to help Pennsylvania dairy farmers with stray voltage problems. It secured state funding to do a short-term research project on the most effective methods of detecting and evaluating the problem.

Study under way.

Now Bob Graves, Penn State ag engineer, is in the process of identifying dairy farms that believe they have a stray voltage problem. He will select six farms to study more intensively.

In the end, he said, he will choose two or three farms that seem to have the most severe undefined voltage problems to do a complete evaluation in an effort to establish new state-wide standards on best methods to evaluate and correct stray voltage.

According to Pennsylvania Grange spokesman James Mentzer, the current Grange initiative on assisting dairy farmers with stray voltage problems is an example of grass-roots democracy in action.

The initial resolution on stray voltage originated with Charlie Wismer at his local Grange, Keystone #2, in Montgomery County.

Wismer said he had been talking to a farm supply service technician who told him of at least 50 cases of stray voltage he had worked on in Montgomery County alone.

And Wismer said there were two members of his local chapter who had struggled to identify the problem and correct it at considerable expense.

Wismer drafted a resolution to request that the department of agriculture study the problem. It passed up through the Grange and was approved in 1999 by delegates to the annual state meeting.

State task force.

A task force was formed of representatives from the department of agriculture, Penn State University, the Public Utilities Commission, and the Grange to determine what needed to be done.

Meanwhile, the state Grange took the issue to the annual Ag Progress Days show at Penn State and came away with an earful.

Posting a sign, “Got Stray Voltage,” at its booth, the Grange staff heard from dozens of farmers from Pennsylvania, New York and Maryland who stopped by to describe the elusive and often undefinable problems with what they believe to be stray voltage.

According to Penn State’s Graves, when a dairy cow is getting a shock, it is essentially because she has come into contact with two different voltage flows that have at least a two-volt difference between them.

The problem can either be on the farm or coming from the power company, but in some way more voltage has gotten into the power supply system than ought to be there.

On-farm problem.

In most cases, Graves said the problem originates on the farm from a faulty connection.

“A farm environment is extremely hostile to electrical systems,” he said. “It can all have been rewired last year, and still have developed bad connections.”

“That will always be the first place to look.”

There are times, however, when the problem is coming from the power system. In that case, voltage is flowing into the grounding wires and then spreading through the metal structures to which wiring is normally attached.

Since the electrical delivery system in this country also includes the ground, Graves said when a cow stands on concrete, she receives one level of voltage from the ground and another from metal she touches.

And when she is being shocked on a regular basis, the stress has an effect on milk production.

Answers elusive.

But while the problem itself is straightforward, Graves said determining whether a production problem on any one farm is actually stray voltage or one of a dozen other things, and finding the source of stray voltage often is not.

The farms in the study will receive voltage meters that will be left in place for several days to determine if there is an unusual voltage flow at any time.

A one-time reading is not very useful, Graves said, because the problem often happens at a particular time, when a certain piece of electrical equipment is in operation.

If a problem is identified that can be corrected, it will be fixed and that farm will end its involvement with the study.

The final two or three farms, he said, will be among those that have had particularly severe problems that eluded solutions.

Stray voltage, Graves said, first came to the attention of the dairy community in the Pacific Northwest in the late 1960s, and has been studied ever since.

Had active program.

In the 1980s, Pennsylvania had an active program to educate farmers and utilities, and by 1990 the agriculture community felt it had a good handle on what was happening and how to deal with it.

Part of the problem now, Graves said, is in the attrition of the people who were were well informed at that time. Some of the information that was put into practice then, he said, has been lost.

But there is also a problem in the number of people who have become involved in testing.

Everybody does it differently, and each method of testing can come up with its own answer, he said.

“If a farmer is convinced he has stray voltage even if one test has proven negative, and someone else finds it, he is going to believe the test that proves him right,” Graves said.

The stray voltage task force has determined that what the state now needs is to look at all the latest technology to determine what is the most effective way to detect the problem, and to develop state guidelines on how such testing should be done.

Grange Day emphasis. The Pennsylvania Grange will continue its initiative to raise awareness of stray voltage by making it the centerpiece of its State Grange Legislative Awareness day in Harrisburg.

Mark Cook from the Michigan Public Service Commission, a national expert on stray voltage, will be keynote speaker for the 300 to 400 Grange members who attend the annual Grange Week celebration April 30.

On May 1, Cook will address a joint session of the Pennsylvania legislature and the Pennsylvania Department of Agriculture.

(You can contact Jackie Cummins at 1-800-837-3419, ext. 23, or by e-mail at


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