The pool water bonding orignated from a report published by the National Electric Energy Testing Research and Application Center and submitted to the NFPA under proposal 17-122 of the 2007 ROP.
In short, the study performed by them basically shows that pool acts musch like a battery. The mix of conductive elements, water, and chemicals will allow the flow of current across the body of a human within the water. Tests showed that an intentional bond to the water elminated this hazard.
In most cases, other bonded items such as ladders, handrails, pool ight shells, etc. will serve as the bond. When those items are not present, another means must be provided such as a metal plate imbedded in the side or bottom of the pool, or perhaps a short section of metallic piping within the circulating system.
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Bryan P. Holland, MCP