At EC&M, we know NEC issues are very important to our readers. That's why we've dedicated a monthly department to answering your latest Code questions and concerns. When you find yourself stumped by the Code, just e-mail your question to firstname.lastname@example.org for future consideration in Code Quandaries.
Q. I thought no foreign systems such as an air-duct system could enter an equipment room, unless that system ended in the room and served the room. Am I correct?
A. No. The NEC does not prohibit foreign systems such as a duct, sprinkler-piping, water-piping, or drain-piping system from entering or passing through an electrical equipment room. However, foreign systems must not intrude into the working space area in front of the electric equipment. The Code defines working space in Sec. 110-26 as the area in front of electrical equipment. This space is not less than 30 in. wide, 3 ft to 4 ft deep (depending on the conditions), and 6½ ft high. In addition, it prohibits foreign systems in the dedicated space area above and below equipment. Dedicated space is defined in Sec. 110-26(f)(1)(a) as the area equal to the width and depth of panelboards, switchboards, and motor control equipment, extending from the floor to a height of 6 ft above the equipment or to the structural ceiling, whichever is lower.
Q. An electrical inspector just informed me that you can't install low-voltage lighting fixtures within 10 ft of the edge of a pool or spa, even though the 110V power supply (transformer) is located 50 ft from the water's edge. Does the NEC allow low-voltage lighting closer than 10 ft from the water if the circuit for the transformer is GFCI-protected? I understand Sec. 680-6(b)(a) allows 120V lighting fixtures to be located just over 5 ft from the water's edge and GFCI protection is not required. Please clarify.
A. Sec. 411-4 specifies that you shall not install low-voltage lighting systems (operating at 30V or less) within 10 ft of pools, spas, fountains, or similar locations. There is no exception to this rule (Fig. 2). Placing the primary circuit conductors (120V) on a GFCI protection device does not protect against an electric shock on the secondary, because the primary GFCI would not sense a fault on the low-voltage secondary.
Sec. 680-6(b) does permit 120V circuits within 10 ft (but no closer than 5 ft) because 120V circuits are contained in a Chapter 3 wiring method (raceways and boxes), whereas the low-voltage cables for low-voltage lighting are not required to be within a raceway or enclosure.