Navigating the NEC's Rules for Bodies of Water
Water-filled structures near electricity are fairly common — you can find swimming pools in hotels, backyards, apartment complexes, health clubs, municipal facilities, and some corporate campuses. Spa and hot tub installations far outnumber pools, and fountains seem to be everywhere — parks, shopping malls, and even building lobbies. If you haven't already worked on one of these installations, chances are someday you will, so it's important to understand the Code requirements that pertain to them.
The requirements of Art. 680 apply to the installation of electric wiring and equipment for pools, fountains, hot tubs, spas, and hydromassage bathtubs, whether permanently installed or storable. For the purposes of this article, these installations will be referred to as bodies of water. As with all Articles in Chapter 6 of the NEC, the basic requirements of Chapters 1 through 4 also apply (680.3).
Per 680.7, you can use cord-and-plug-connected equipment for a fixed or stationary pool, outdoor spa, or hot tub, provided:
The cord doesn't exceed 3 ft.
The cord has a copper equipment grounding conductor not smaller than 12 AWG that terminates to a grounding-type attachment plug.
You must install pools, spas, hot tubs, diving structures, observation stands, towers, and platforms at least 10 ft from overhead conductors (680.8). Service drop and open overhead conductors aren't the only things to consider — the section also applies to communications cables for telephone, radio, and CATV. The clearances are even greater for network-powered broadband communications systems. Broadband cable must be located no less than 22.5 ft from water or the base of diving structures, and no less than 14.5 ft from observation stands or diving platforms.
Underground wiring isn't permitted under bodies of water. Wiring within 5 ft horizontally of the inside wall of a body of water must be installed in rigid metal conduit (RMC), intermediate metal conduit (IMC), or a nonmetallic raceway system (680.10). Use the burial depths shown in Table 680.10.
Be careful when working with drainage and disconnects. All equipment rooms and pits must have adequate drainage for normal operation and filter maintenance (680.11). You must provide a means to disconnect all ungrounded conductors for equipment other than lighting (680.12), and the disconnecting means must be accessible and within sight (within 50 ft) of its equipment. Locate switches at least 5 ft horizontally from the inside walls of the body of water, unless separated by a solid fence, wall, or other permanent barrier [680.22(C)].
Install branch-circuit conductors for the motors in RMC, IMC, rigid nonmetallic conduit (RNC), or Type MC Cable listed for installation in direct sunlight or direct burial (680.21). Include a copper equipment grounding conductor not smaller than 12 AWG. Electrical metallic tubing (EMT) is permissible for use above grade if the wiring is installed on or within buildings. You can use liquidtight flexible metal or nonmetallic conduit, if you do so per the requirements of Art. 356.
Area lighting, receptacles, and equipment.
Receptacles for loads directly related to the circulation system that meet requirements listed in 680.22(A)(1) may be located not less than 5 ft from the inside wall. All other receptacles must be 10 ft from the water.
At a dwelling unit, you must install one 15A or 20A, 125V receptacle not less than 10 ft and not more than 20 ft from the water. This receptacle must be not more than 6.5 ft above the floor, platform, or grade level serving the body of water. That separation can be smaller in areas with restricted space (Fig. 2 at right). All receptacles must be GFCI-protected.
New luminaires and ceiling fans installed near bodies of water must also meet minimum height requirements. Height requirements differ for existing luminaires, which must be GFCI-protected, rigidly attached to the structure, and located at least 5 ft horizontally and vertically from the water. Low-voltage lighting systems, such as those covered by Art. 411, can't be installed within 10 ft of the vessel.
Panelboards, time clocks, and other switching devices must be located at least 5 ft horizontally from the inside walls of a pool or tub unless separated by a solid fence, wall, or other permanent barrier.
The requirements for underwater luminaires appear in detail in 680.23, but let's look at some highlights. In all cases, you may install only luminaires listed for this purpose.
Mount the luminaire so the top of the lens is at least 18 in. below the normal water level. Note that 680.23 has specific grounding requirements for the raceway and any flexible cords used to power the luminaires. The raceway must be RMC, IMC, RNC, or liquidtight flexible nonmetallic conduit. You can use EMT where installed on or within buildings.
If a branch circuit supplies more than one underwater luminaire, the equipment grounding conductor can terminate to a listed pool junction box that meets the requirements of 680.24(A). Luminaire branch-circuit conductors on the load side of a GFCI or transformer can't occupy raceways, boxes, or enclosures containing other conductors unless the other conductors are GFCI-protected, serve as grounding conductors, supply a feed-through type ground-fault circuit interrupter, or are in a panelboard.
Extensive instructions for the installation of junction boxes and enclosures are located in 680.24. In all cases, use only junction boxes and enclosures listed for this type of application.
Locate the junction box not less than 4 in. above the ground or pool, spa, or deck, or not less than 8 in. above the maximum water level. It should be at least 4 ft from the inside wall of the body of water, unless separated by a permanent barrier. Don't locate boxes in the walkway unless they're protected by some other structure, such as a diving board.
You must provide the junction box with one more grounding terminal than the number of conduit entries. Typically, there are four grounding terminals in the junction box and three conduit entries, so this shouldn't be a problem.
Install feeder conductors in RMC, IMC, RNC, or liquidtight flexible nonmetallic conduit (680.25). You can use EMT where installed on or within buildings. However, branch circuits can come from an existing panelboard supplied by a cable assembly that includes a grounding conductor within its outer sheath.
The bonding required by 680.26 helps eliminate voltage gradients in the pool area by forming a common bonding grid. Bonding isn't required to provide a low-impedance ground-fault current path. The following objects must be bonded to the type of common bonding grid specified in 680.26(C):
- Metallic parts.
All metallic parts of the water structure, including the reinforcing metal of the pool shell, coping stones, and deck, are subject to the requirements of 680.26(C). Steel tie-wires made up tight are suitable for bonding reinforcing steel (Fig. 3 above).
- Underwater lighting
Bond the metal forming shell used to contain underwater luminaires or speakers.
- Metal fittings
Bond metal fittings within or attached to the structure, such as ladders and handrails.
- Electrical equipment.
Bond metal parts of electric equipment associated with the water circulating system, such as water heaters and pump motors. For a double-insulated water-pump motor, provide a solid 8 AWG copper conductor from the bonding grid to an accessible point in the motor's vicinity.
- Metal wiring methods and equipment
Bond metal piping, fixed metal parts, observation stands, towers, platforms, or diving structures, as well as metallic surfaces of electrical equipment located within 5 ft horizontally of the inside walls of the structure, and within 12 ft of the maximum water level. Bond diving structures, sliding glass door frames, windows, fences, screen enclosures, heater equipment, and the metal cases of electrical equipment located within 5 ft of the water's edge.
The requirements for this bonding grid, specified in 680.26(C), include bonding with a solid conductor not smaller than 8 AWG. You can terminate the conductor by exothermic welding or with clamps labeled or listed for the purpose.
Art. 680 boils down to two concepts: separation and bonding. Separate water from electricity by the clearances required for each of the items installed. You must bond all non-current carrying conductors and metal parts to prevent a difference of potential. If you keep these concepts in mind, you'll stay afloat in the sea of NEC rules.