Code Q&A - July 2013
What is equipotential bonding for permanently installed pools?
The equipotential bonding for swimming pools is required as per Article 680.26 (A) to reduce voltage gradients in the pool area creating an electrically safe environment in and around the permanently installed swimming pools. This bonding system establishes an equal electrical potential (voltage) in the vicinity of the pool and reduces possible injurious or disabling shock hazards.
- The parts specified in 680.26(B)(1) through (B)(7) shall be bonded together using solid copper conductors, insulated covered, or bare, not smaller than 8AWG or with rigid metal conduit of brass or other identified corrosion-resistant metal. Connection to bonded parts shall be made in accordance with 250.8. An 8AWG or larger solid copper bonding conductor provided to reduce voltage gradients in the pool area shall not be required to be extended or attached to remote panelboards, service equipment, or electrodes.
- 680.26(B)(1) Bonding to conductive pool shells shall be provided as specified in 680.26(B)(1)(a) or 680.26(B)(1)(b). Poured concrete, pneumatically applied or sprayed concrete, and concrete block with painted or plastered coatings shall all be considered conductive materials due to water permeability and porosity. Vinyl liners and fiberglass composite shell shall be considered to be nonconductive materials.
- Unencapsulated structural reinforcing steel shall be bonded together by steel tie wire or equivalent. Where structural reinforcing steel is encapsulated in a nonconductive compound, a copper conductor grid shall be installed in accordance with 680.26(B)(1)(b) a copper conductor grid shall be provided and shall: (1) be constructed of minimum 8 AWG bare solid copper conductor bonded to each other at all points of crossing and in accordance with 250.8 or other approved means (2) conform to the contour of the pool, (3) be arranged in a 12- in x 12-in (300-mm x 300-mm) network of conductors in a uniformly spaced perpendicular grid pattern with a tolerance of 4in.(1oomm), and (4) be secured within or under the pool no more than 6in.(150mm) from the contour of the pool shell.
- 680.26 (B)(2) The perimeter surface shall extend for 3ft (1m) horizontally beyond the inside walls of the pool and shall include unpaved surfaces, as well poured concrete surfaces and other types of paving. Perimeter surfaces less than 3ft (1m) separated by a permanent wall or building 5ft (1.5 m) in height or more shall require equipotential bonding on the pool side of the permanent wall or building. Bonding to perimeter surfaces shall be provided as specified in 680.26(B)(20(a) or (20(b) and shall be attached to the pool reinforcing steel or copper conductor grid at a minimum of four (4) point uniformly spaced around the perimeter of the pool. For nonconductive pool shells, bonding at four point shall not be required.
In closing the equipotential bonding grid for a permanent swimming pool is formed by connecting together all of the following with a 8 AWG solid copper conductor and listed clamps suitable for direct burial or embedded in concrete are indentified (DB) for Direct Burial and also suitable for concrete encasement without additional markings. Diving Structures, Metal Forming Shells, Handrails and Ladders, Pool Cover Motors and Metal Parts, Fences, Metal Rope Hooks and Pump Motors.
Marc Ramirez has been a member of the NEC Code Making Panel 17 since 1993 and is a member of the IEC National Codes and Standards Committee. He can be reached at (623) 256-9331.