Measured Breakdown Voltage and Leakage Current of Line Worker Boots

Sixty-hertz breakdown voltage and leakage current for 48 pairs of used line worker boots were measured under dry and wet conditions. Line workers wear conventional work boots, hiking boots, or traditional lineman boots. The outer soles of work and hiking boots are predominantly a single molded piece, called a unisole; lineman boots generally have a separate heel nailed to the sole. Our survey found mainly (81%) unisole work and hiking boots. Laboratory measurements showed dry and wet breakdown were associated with sole and boot type but not with recent use, resoling, or estimated wear. Unisole boots had higher resistances and withstand voltages than separate-heel construction. Breakdown occurred at much lower voltages for wet conditions than for dry. Wet breakdown voltage determined the electrical integrity of boots for leakage currents of 50 mA or higher. For lower currents, leakage and boot resistance were the determining factors for minimizing risk from shocks.