A problem on dairy farms is "stay voltage," caused by corroded wiring, poor wiring practicies, or ground currents associated with nearby power lines. These conditions can result in several volts of potential difference between metal objects such as watering bowls, feed troughs, or milking equipment, and the ground. Cows feel slight shocks that make them nervous, resulting in reduced milk output. As a result, farmers can face serious financial losses. Figure 28-69 shows a circuit model for a stray voltage situation; the 1.5 kilo-ohm resister represents the resistance of corroded connections and poor wiring; you can assume the ground has negligible resistance.