Stray Voltage

What Is Stray Voltage?

Stray voltage is a natural phenomenon that can occur on a grounded neutral system of a customer’s wiring or a utility’s distribution system. If a person or animal touches grounded metal equipment under certain conditions, voltage on the neutral system can cause current to flow through the animal or person into the ground. Usually, this stray voltage is not strong enough to harm the person or animal.

Threshold Levels

Idaho Power has established a tolerance threshold of 1 volt at the livestock point-of-contact. This is 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 problems on our 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 their research, stray voltage can be kept at levels that don’t affect dairy livestock health or production. This was substantiated in the United States Department of Agriculture Handbook 696, 1991, Effects of Electrical Voltage/Current on Farm Animals–How 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 Our trained technicians will visit your property, measure voltage levels and explain how to repair outdated wiring to help reduce stray voltage. A downloadable walk-through checklist will help you inspect areas where stray voltage levels might be higher than normal.

The presence of stray voltage at a dairy farm is impossible to eliminate without giving up features that maintain reliability, equipment protection and the safety of humans and animals. However, there are options available to reduce stray voltage enough 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 Idaho Power’s more extensive grounding system. 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 to a power quality engineer.

Additional Information

The USDA Handbook 696 contains additional information on stray voltage and livestock. This PDF can 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.