Stray Voltage

What Is Stray Voltage?

Stray voltage is a natural phenomenon. It is a voltage that can develop on a grounded neutral system of either a farm’s wiring or a utility’s distribution system. If an animal touches grounded metal equipment under certain conditions, voltage on the neutral system can cause a small current to flow through the animal into the ground. Usually, the amount of this stray voltage is not enough to cause physical or behavioral changes in the animal.

Threshold Levels

Idaho Power has established a threshold level of 1 volt at the livestock-point-of-contact. This is slightly less than the voltage of a single standard flashlight battery (1.5 volts) and is consistent with U.S. Department of Agriculture findings.

If levels above 1 volt are detected, the company will determine the degree to which the levels can be attributed to the company’s system and the degree to which they can be attributed to the customer’s electrical system. Our stray voltage technicians will take necessary steps to remedy any issues with the system and advise the customer of possible actions to address those originating at the customer’s facility.

Research on Stray Voltage

Stray voltage is often misunderstood. Over the past 40 years, the U.S. Department of Agriculture and other federal, state, utility and dairy organizations have conducted studies on stray voltage. According to these authorities, stray voltage can be kept at levels where dairy livestock health and production are not affected. This was substantiated in the United States Department of Agriculture Handbook 696, 1991, Effects of Electrical Voltage/Current on Farm AnimalsHow to Detect and Remedy Problems and other national and international research.

What You Can Do

If you have concerns about stray voltage on your property, please contact us. Our trained technicians will visit your property, measure voltage levels and explain how to repair outdated wiring on the farm to help reduce stray voltage. A downloadable walk-through checklist will help you inspect areas on your farm where stray voltage levels might be higher than normal.

The presence of stray voltage at a dairy operation is impossible to eliminate without giving up features of the system’s design that address reliability, equipment protection and the safety of humans and animals. However, there are options available to reduce stray voltage to the point that it has no adverse effect on livestock or livestock operations. We make every effort to ensure such efforts result in the protection of all customers’ best interests.

By request, we will install a neutral isolator at a facility, completely separating the customer’s grounded system from the broader and more extensive grounding system of Idaho Power. For more information on the risks associated with this option, please call Idaho Power’s customer service center at 1-800-488-6151 or 208-388-2323 from the Treasure Valley and ask to speak with a power quality engineer.

Additional Information

The USDA Handbook 696 contains additional information on stray voltage and livestock. This PDF may take up to 17 minutes to download. To request a paper copy of the handbook, call Idaho Power at 1-800-488-6151 or 208-388-2323 from within the Treasure Valley.

You can also view our stray-voltage brochure.

For assistance with a PDF on this page or to request a PDF in an alternate format, please contact Customer Service at 208-388-2323 or 1-800-488-6151