Another frequent violation occurs around swimming pools, spas, fountains and similar areas. NEC 411.4(2) does not permit low-voltage lighting systems within 10 feet of these areas, unless permitted by Article 680. Section 680.22(B) covers area lighting around a pool. Any luminaire installed within 5 feet horizontally of the pool edge must be located at least 12 feet above the maximum water level of the pool. There are many existing low-voltage lighting installations installed after the pool installation inspection has occurred where the luminaires are installed within 3 to 5 feet of the water?s edge at or near ground level, which clearly is a violation.
Section 680.22(B)(4) permits luminaires to be installed within 5 to 10 feet horizontally of the pool?s edge only where a ground-fault circuit interrupter (GFCI) protects the luminaires. Since low-voltage landscape luminaires are supplied by a low-voltage power supply, such as a transformer, providing GFCI protection on the primary side of an isolation transformer will not provide GFCI protection on the secondary side. GFCI devices will not operate at the 15-volts or less supplied by the secondary of the power supply. This leaves only two options: one is to locate all low-voltage landscape lighting at least 10 feet from the pool or fountain edge; or, two, to use a special power supply.
There are low-voltage lighting power units that are marked ?For Use with Submersible Fixtures or Submersible Pumps.? In this case, a special transformer is used that complies with the requirements in 680.23 for underwater luminaires installed below the normal water level of the pool. This transformer is specifically listed for this use and is an isolated winding type transformer with an ungrounded secondary similar to the low-voltage landscape lighting transformer, as required by 411.5(B). The low-voltage pool lighting transformer has one additional feature in its design. It has a grounded metal barrier or shield between the primary and the secondary. This metal barrier or shield prevents a direct internal short between the primary and the secondary of the transformer. If a short does occur on the primary side, it will short to the metal shield and the primary overcurrent protective device will operate. If a short develops on the secondary side to the shield, the secondary overcurrent protective device, if provided, will operate. If there isn?t a secondary overcurrent protective device and the primary is providing protection through the transformer, the primary device should operate.
