Electrical grounding, pipe integrity, and shock hazard

Abstract

Electrical currents on metallic water service lines and mains affect corrosion of buried metal piping and can result in random shock hazards for water utility employees. The practice of using metallic water piping as part of the electrical grounding system of a building has been commonplace for more than 80 years. Modern electronics such as variable‐speed motors, televisions, and computers produce both direct current and alternating current (AC), which can flow along metallic water service piping. When electrical transformers serve multiple buildings, the water services and distribution piping can act as parallel neutral return paths for AC from building electrical systems to the transformers. AC can increase the rate of corrosion of distribution and service piping and create shock hazards for distribution workers. As long as the current remains on the electrically continuous pipe, corrosion is not affected. Corrosion occurs when current leaves the pipe and flows through the earth.

Issues associated with use of dielectrics in drinking water systems

“…Use of water pipes for electrical grounding has long been a controversial subject (Duranceau et al, 1998; Horton, 1995; Carlton, 1974), and there have been well‐documented cases of service line failure because of external corrosion, electrocution of utility employees, and evidence of excessive metal leaching to potable water in at least some plumbing configurations (Bell & Duranceau, 2002; Duranceau et al, 1998; Horton, 1995; Carlton, 1974). In cases in which a service line carries stray current from a miswired electrical system, a dielectric could reduce the risk of electrocution to utility employees.…”

“…Decreases electrocution risk to utility workers from improper electrical wiring Reduces grounding effectiveness Carlton, 1974;Duranceau et al, 1998;Horton, 1995;Welter, 2008 Water quality (higher Pb, Fe in water)…”

Effect of Grounding and electrical properties ON WATER QUALITY

“…The discharge of current on the interior of the pipe can increase the metal content of the water. Various utilities had verbally provided information about their experiences with degraded water quality caused by grounding currents (Duranceau et al, 1996). The LCR requires water treatment as a method for corrosion control and reduction of metal concentrations at the customer's tap if the concentration of lead (Pb) or copper (Cu) exceeds specified limits.…”

“…In order to better understand the consequences of grounding the electrical system of a building to water pipes, the AWWA Research Foundation funded a study to evaluate the effects of grounding on pipe integrity and shock hazard. The results of those investigations have been published (Duranceau et al, 1998; Duranceau et al, 1996). This article presents results from one portion of the study, which looked into how grounding affects pipe metal release and water quality.…”

Effect of RuCl3Concentration on the Lifespan of Insoluble Anode for Cathodic Protection on PCCP

“…In two studies supported by the American Water Works Association Research Foundation (AWWARF) researchers developed methodologies to identify the sources of stray currents in order to protect pipelines from the adverse effects of stray currents. They also identified issues that need to be tackled while grounding electric utility items 7,8) . Many researchers have proposed the use of pulsed cathodic protection 9).…”