Stray Voltage

Is It Really a Problem?

Abstract

In order for any discussion on stray voltage to be meaningful we first have to define what is meant by stray voltage. For the purposes of this paper I will use the definition found in the USDA Handbook 696, "EFFECTS OF ELECTRICAL VOLTAGE/ CURRENT ON FARM ANIMALS -- How To Detect and Remedy Problems."¹ That definition reads as follows: "Stray voltage is a small voltage (less than 10V) that can be measured between two possible contact points. If these two points are contacted by an animal or person, a current will flow. The amount of current depends on the voltage and the circuit impedance, which includes the source, contact and body impedances. Animals or persons respond to the resulting current flow and not the applied voltage." From this definition there are two things I want you to notice:

First, stray voltage is found at cow contact points. It is not voltage found between a reference ground rod and the service entrance neutral wire (neutral to earth voltage [nev]) or the water bowl or any other contact point in the barn. Voltage between those points may indicate possible stray voltage but they are not stray voltage in themselves.¹

Second, it is not the voltage, but the current, which the animal reacts to so any stray voltage investigation should determine current as well as voltage. We will discuss these points in more detail later.