Comparison of the Coupling of Grounded and Ungrounded Humans to Vertical 60-Hz Electric Fields

摘要

Total induced currents and average induced axial current densities have been published in the literature for human models exposed to 60-Hz electric fields. The results of these studies have been quite useful, but they deal with a somewhat idealized exposure situation that ignores the insulating effects of most types of footwear. This paper describes a new laboratory technique for studying the relationship between grounded and ungrounded exposure of humans. A conducting model of the body 40-cm-tall man was electrically divided into seven segments. Wires connected to the conducting surfaces of these segments were routed horizontally through shielded cable to remote, battery-powered electronics. The ''common'' potential of the electronics was biased to the electric-field-induced potential of the model, allowing us to accurately measure the current induced in each body segment of the model. The method was tested by measuring the current induced in the upper hemisphere of a ungrounded sphere: agreement between theory and measurement was excellent. Measurements were made with the human model located at 15 positions, ranging from touching ground to remote from ground (i.e., in free space). The ratios of free-space to grounded currents crossing horizontal sections through the body were: neck, 0.58; chest, 0.40; abdomen, 0.39; thigh, 0.36; ankle, 0.17. (ERA citation 11:036892)