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The use of metallic water piping as part of a building's electrical grounding system has beena commonplace practice for more than 80 years. When electrical transformers serve multiplebuildings, the water services and distribution piping can act as parallel neutral return pathsfor stray current from building electrical systems to the transformers. Electrical resistance inpipe connections, if present, forces some fraction of the stray current to flow through theparallel water path. Discharge of current on the inside of the pipe increases metal release.Previous studies on the effects of grounding on water quality and metal release did notinvestigate the effects of resistance or dielectric fitting. This study investigated the effects ofdielectric fittings on water quality. Copper tubing that had been modified with inserteddielectric fittings was filled withpotable water from two differentwater sources and was tested withapplied alternating current (AC)voltages of up to 123 V for periods ofup to 110 h. Significant increases incopper, lead, and zinc in stagnantpotable water were measured in lessthan 24 h at applied voltages of ~50VAC. Metal release generally increasedwith charge transfer, inaccordance with Faraday's law. Includes 13 references, tables, figures.

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Edition: Vol. 94 - No. 5 Published: 05/01/2002 Number of Pages: 13File Size: 1 file , 480 KB