The objective of this four-volume report was to investigate the application, economic, and safety considerations of electrical-shock prevention techniques applied to surface and underground mines. This report is primarily concerned with the protection of maintenance personnel. The scope of the work is specified, electrical shock is defined, and needed ground-fault relay characteristics to prevent ventricular fibrillation are established. This is followed by an analysis of ac systems, a comparison of these systems with respect to body currents, the advantages and disadvantages of the various ground-fault protection techniques, and an analysis of DC systems for off-track vehicles. Summaries and synopses of each of the three remaining volumes are included.