Stray Voltage - Idaho Power

What Is Stray Voltage?

Stray voltage is a small electrical voltage that can exist between two conductive surfaces that a person or animal could touch at the same time. These small voltages occur naturally as electricity flows through utility and customer electrical systems. In most situations, the voltage is too low to be felt or to cause any effect.

Because farm environments bring together livestock, electrical equipment, and electrical grounding systems, it’s normal for small voltages to appear between grounded metal structures, floors, or other contact points. These small voltages do not necessarily indicate an electrical fault or malfunction.

Stray voltage cannot be completely eliminated without compromising the safety, reliability, and protective grounding practices used in modern electrical systems. However, it can be effectively managed so it has no adverse effect on livestock or dairy operations. Our goal is to work closely with you to maintain a safe, productive, and dependable environment for your operation.

Managing Stray Voltage on Farms

The U.S. Department of Agriculture (USDA) recommends keeping cow‑contact voltages from low‑impedance sources below 2 to 4 volts, which research has shown does not affect livestock health or production. The state of Idaho uses a more conservative threshold of 1 volt (60 Hz, steady‑state RMS) at cow‑contact locations. This is less than the voltage of a standard AA flashlight battery.

To help you review your electrical system and identify common issues, we offer a downloadable checklist.

If elevated levels are found on your property, Idaho Power specialists can help determine contributing sources, including what portion originates from Idaho Power’s system and what portion may come from the farm’s wiring or equipment. We will then work to reduce Idaho Power’s system contribution to 0.5 volts or less and provide guidance on actions you can take within your own facility.

How We Can Help

If you have questions or concerns about stray voltage on your property, we’re here to help and can provide a free on-site evaluation. Just call our Customer Care Team at 208-388-2323 or 1-800-488-6151 and request to speak with a stray-voltage specialist.

During on-site evaluations, a trained stray-voltage specialist will visit your property to:

Measure stray‑voltage levels at relevant contact points
Compare results to Idaho’s established threshold
Identify potential contributing sources
Evaluate Idaho Power’s neutral‑grounding system so we can make any needed repairs or improvements
Provide practical steps to reduce or eliminate contributing factors within your facility

More Resources

Stray voltage has been extensively studied for decades by universities, the USDA, and other federal, state, utility, and dairy organizations. These studies consistently show that stray voltage can be managed to levels that do not adversely affect dairy livestock health, behavior, or productivity. More information is available in USDA Handbook 696, Stray Voltage/Current: Effects on Farm Animals.

Our stray voltage brochure is also available for download. For additional support, please contact Idaho Power’s Customer Care Team at 208-388-2323 or 1-800-488-6151 and request to speak with a stray-voltage specialist.