Stray voltage is an issue of particular concern among dairy and other livestock farmers. Stray voltage is a phenomenon associated with on-farm wiring and electrical connections to the local distribution system.
The United States Department of Agriculture defines stray voltage as “a difference in voltage between two surfaces that may be contacted simultaneously by an animal.” On a farm, these surfaces may include stanchion pipes, water cups and feeders. When stray voltage occurs on a dairy farm, the cow closes the circuit and, if voltage levels are high enough, the animal may experience a small shock or tingle.
The term stray voltage is often used incorrectly to refer to other electrical phenomena such as electric fields, magnetic fields and most recently electric current flowing in the earth. These phenomena are generally referred to as electric and magnetic fields.
Although stray voltage can’t be totally eliminated, it can be minimized.
Causes of stray voltage
Many things can contribute to stray voltage. Some more common sources include:
- inadequate connections on the neutral or ground wire system,
- poor grounding conditions,
- undersized neutral conductors,
- dirty, dusty, corroded or damaged electrical boxes and devices,
- unbalanced 120-volt loads,or
- defective electrical equipment.
Under less common circumstances, interaction between parallel electric transmission and distribution systems may add to the risk factors that can contribute to stray voltage in an animal confinement area.
Stray voltage mitigation
Jointly, the Public Service Commission of Wisconsin and the Wisconsin Department of Agriculture, Trade and Consumer Protection have established the Rural Electric Power Services Program to work with farmers in resolving herd health and production problems, and to provide outreach and technical assistance.
Since stray voltage is a phenomenon most often associated with on-farm wiring and electrical connections to the local distribution system, questions and concerns about stray voltage are best addressed initially by the local distribution utility that serves the facility or farm. The local distribution company will perform an on-farm stray voltage investigation, and will work with ATC on individual investigations where transmission line configuration is among the list of potential risk factors to better understand the interactions between both systems. If you think stray voltage may be an issue on your property, contact your local electric utility.
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