When was pool bonding first required by code?
Monday, May 6, 2019
Stray electrical currents, or differences in electrical potential between two points, can occur between a pool, the pool equipment, and the surrounding metal objects such as nearby windows of a home. So the National Electrical Code (NEC) requires that the pool equipment, and all metal within a 5-foot radius of the edge of the pool up to 12-feet high be connected together with copper wiring to the metal reinforcing steel in the pool and the panel ground. This is called equipotential bonding.
Swimming pools first appeared in the NEC in the 1962 edition, and the section was a brief three pages long. Here’s the first bonding citation in the 1962 code, although it was not initially called bonding:
- (a) All metallic conduit, piping systems, pool reinforcing steel, light fixtures, and the like, shall be bonded together and grounded to a common ground. The metal parts of ladders, diving boards, and their support, shall be grounded.
- (b) No pool equipment shall be grounded to an external grounding electrode that is not common to the pool ground (deck box or transformer enclosure).
- (c) An unbroken No. 14 AWG, or larger, insulated copper wire shall be provided for a grounding conductor from the deck box to the distribution panel ground.
- (d) Metallic raceways shall not be depended upon for grounding. Where exposed to pool water and in other corrosive areas such as in pump houses or adjacent to water treating and other equipment, the grounding of the non-current carrying parts shall be by means of an insulated copper conductor sized in accordance with Section 250-95.
The 1965 edition changed the ground wire requirement from #14 AWG to the larger #8 AWG, along with other minor additions. Then the 1968 edition introduced the word “bonding” for the unbroken connection between all components that was required, and specified the five-foot radius rule that we know today. Equipotential bonding code has continued to be improved in each code cycle up to today.
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Here’s links to a collection of our other blog posts about POOL AND SPA:
Thanks to Jerry Peck, Construction/Litigation Consultant, for his code history notes used for this article.
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