All stray voltage is unintentional and undesirable, yet it is common. In fact, it would be rare to find a farm or home without it, usually not in a good location.

The main culprit, even though there are several variations of causation, is that with all standard 120 volt wiring there is only have one hot wire, one neutral wire and a ground wire.

If the neutral wire is inadequate or if there is a weak or failed connection, the electrical current arriving on the hot wire must return to the source in some manner, which means it will try to go through any and all other objects that will conduct electricity. This undesirable flow of electrons can be via the earth, water, metal buildings, fences or other objects.

A farmer had a grinder in the shop with a minor short in the motor; when it was turned on, it would give out a little shock. He “cured” the problem by turning on the grinder switch with a wooden broomstick. On another farm there was a series of five livestock water fountains all connected to the electrical line. The first four fountains seemed normal, and the cattle were approaching them casually and drinking water normally. However, the cattle seemed to sense something was wrong with the fifth fountain, and they avoided it. Thirsty, two young heifers approached the fifth fountain, which also was overflowing and creating a puddle they were standing in. Within seconds after touching the water in the fountain, both heifers were killed.

What is stray voltage?

This is a very aptly named problem, in that it applies to any two objects that have electrical potential between them that ideally should not have any voltage difference between them. How much does it take? In general, we are always hoping for zero voltage; however, almost any animal can easily feel anything at 0.5 volts or higher. Humans could feel it too, but we usually have shoes or boots on and sometimes gloves.

Electrical engineers, including agricultural engineers, are trained to see electrical current wherever it is, quite like the rest of us might see water flowing. We could hardly expect to see water flowing into a structure without knowing where and how this water will exit. With voltage, if the neutral wire is not fat enough, or if the distance is too far, there’s no way it can keep up with electrical flow so that current “spills” into other areas in order for it to eventually get back to the source.

Stray voltage can come from any electrical device that is malfunctioning. Even properly installed wiring or devices can be damaged by moisture, lightning or mice, squirrels and rats. Most commonly afflicted are barn fans in the summer and water tank heaters in the winter. Lastly, there often can be problems coming onto your farm from the utility service. Wherever the source, proper diagnosis is a critical starting point.

Symptoms of stray voltage

Many farmers think they must be bad farmers or bad managers, or that they must have poor-quality livestock, not realizing there is a hidden cause. Electricity is essentially invisible, and we are usually focused on visible issues. Every single farm, ranch barn, garage or home can have stray voltage problems. We have seen it with dairy, beef, swine, sheep, goats, poultry or horses, but most often electrical problems are most clear in a dairy. In general, dairy animals drink more (to make milk), and they quite often are indoors and being handled in a place where we can watch them.

Animals that are plagued with stray voltage will most frequently manifest specific problems such as mastitis, or high somatic cell count, or they are jumpy when they come in to be milked. In many cases they just will not let down their milk flow. Watch your animals when they drink; they will tell you. Frequently they will only drink just enough to satisfy their thirst but not enough to maintain adequate production, which soon falls off even worse. Instead of taking a steady intake of water, they merely lap at the water, bobbing their heads. Humans are more likely to feel the voltage themselves when walking barefoot on wet concrete, even more so when touching plumbing or metal when they are somewhat grounded by being wet. People have even been known to keep a dry rag around so that they can shut off a faucet without getting a mild shock.

Diagnosing stray voltage

Ideally, hire a pro. He understands both sources of problems and his main tool of the trade is a simple volt meter, one that can measure microvoltage. At times he will hold a metal rod in one hand as he explores with the leads from a volt meter. He also may use a device that converts electrical current into an audible signal which emits a buzz if there is current flow. Quite often he can instantly spot wiring design errors or find loose connections. By the use of such a device he can pinpoint sources of the problem.

Can stray voltage be cured?

Absolutely. However, there can be mysterious challenges. Even if the problem is coming from the utility, a power pole/transformer neutral isolator can be installed.

Since many problems come from inadequate grounding, this is a cure that can be rewired in a proper manner and without much cost. With 240 volt wiring there are fewer problems because there are two hot wires, and the current will arrive via one hot line and go back to the source via the other hot wire.

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Nelson is Oklahoma Cooperative Extension Service ag educator for Garfield County.

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