What to do with Stray Voltage

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This unusual phenomenon, primarily affecting farm livestock, is the result of faulty wiring on any number of electrical systems (not just wind turbines) and easily prevented by industry-standard practices. It is also a strictly localized issue that will not affect off-site parties or properties.

For safety reasons, including to minimize lightning strikes, nearly all types of electrical systems in the U.S. are, at some point in the system, connected to the earth or “grounded.” Electric current flowing in the ground dissipates quickly as it moves away from its source (much like sound from a wind turbine). Grounding also allows power systems to detect equipment malfunctions and automatically shut down before harming people or equipment.

If a system is not properly wired, the point(s) at which a system is grounded can develop a small voltage (electrical pressure, essentially) that can push current through the earth and end up contacting unintended objects. Hence the name, “stray” voltage. This phenomenon is rare and primarily affects cattle, whose legs are far enough apart to stand on two points where different voltage levels in the ground exist. The cow may or may not feel this voltage difference, depending on the level and duration of the exposure.

While the design of electrical system makes stray voltage possible, its actual occurrence is the result of poor grounding practices, improper or inadequate wiring, or deteriorated wire insulation. Most small wind turbine inverters – those that are IEEE 1547 or UL1741 compliant – can detect faulty grounding and automatically shut down current flow. Like solar photovoltaic installations that require “ground-fault circuit interrupter” (GFCI) devices to protect consumers from any stray voltage, small wind turbines are also equipped with GFCI measures.

In other words, stray voltage is caused by problems on a particular customer’s side of the utility billing meter so is not a problem beyond the electrical system of a particular home or farm. Nor can stray voltage move or be transferred from one property to another, since it is an “on-site” problem stemming from electricity distribution or wiring, not the generation of electricity. The issue therefore does not fall under the jurisdiction of zoning rules, which are designed to protect that which exists outside a property line.

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