Q. When installing a grid structure at a dwelling unit swimming pool, the equipotential bonding grid shall cover the contour of the pool and the pool deck.

The grid shall extend _____ inches horizontally from the inside walls of the pool. The grid shall be arranged in a network that is _____ inches by _____ inches, and shall be uniformly spaced in a perpendicular grid pattern with a tolerance of _____ inches.

A) 36 / 12 by 12 / 4
B) 30 / 12 by 12 / 6
C) 30 / 24 by 24 / 6
D) 36 / 16 by 16 / 8

Answer: A

Explanation: The NFPA substantially revised Section 680.26(C), Equipotential Bonding Grid, of the 2005 edition of the NEC. This section now requires you to install an equipotential plane (ground grid), extending out 36 inches in all directions from the inside edge of the pool. The grid shall be arranged in a network of conductors (12 inches by 12 inches) that is uniformly spaced in a perpendicular grid pattern with a tolerance of 4 inches. At all crossing points of the grid, the grounding grid conductor connections shall be made as required by 680.26(D).

The requirements of this section of the Code are similar to the requirements for grounding and bonding equipotential plane(s) as noted in 682.33 for natural and artificially made bodies of water.

Owen is the owner and president of National Code Seminars and the holder of master electrician certifications in 46 states. He can be reached at necexpert@aol.com.