Effects of Stray Capacitance on High Voltage Testing of Vehicle-mounted Elevating and Rotating Aerial Devices in Accordance with Ansi/sia A92

The capacitive effects of a ground plane on an aerial bucket truck undergoing periodic testing can have a significant impact on the measured test results. The capacitive coupling of a building can reduce the leakage current through the boom resulting in a lower reading from the return point of the truck. Since the coupling is not as prevalent outdoors, more current flows through the boom resulting in larger leakage readings. The capacitive effects of a large ground plane (such as a building) are proven both mathematically and with small scale tests.