Journal Executive Summary - Vol. Data from 20 utilities across the United States indicate that serious shock incidents happen at a rate of approximately one per 200,000 domestic service lines each year or approximately 370 a year.
Minor shocks occur much more frequently.
These data were collected as part of a recent investigation into the effects of grounding electrical systems to metallic water services and distribution mains. Modern electronics produce both direct current and alternating current that can flow along metallic water service piping. In addition to posing hazards for water utility personnel, electrical currents on water pipes affect the corrosion of buried metal piping. But insulating water services is not a simple technical decision based on shock hazard or pipe integrity. Insulation or a plastic service line could result in an ungrounded system on structures built before 1993.