Electrical grounding, pipe integrity and shock hazard

Metallic water piping has been used for electrical grounding in buildings for more than 80 years. Modern electronics produce both direct current and alternating current (AC), which can flow along metallic piping. When electrical transformers serve multiple buildings, the piping can act as parallel neutral return paths for AC from building electrical systems to transformers. AC can increase pipe corrosion and create shock hazards for distribution workers. Corrosion occurs when current leaves the pipe and flows through the earth. There are 38 references.