In the Deep End: Underwater Luminaires in Swimming Pools

Code Comments 0419 Photo Credit: Michael Johnston
Photo Credit: Michael Johnston
Published On
Apr 15, 2019

Modern technologies and equipment have found their way into many electrical installations and systems. It seems like the biggest evolution is occurring in lighting, and it brings many benefits with it. Having installed a swimming pool recently, I witnessed this evolution first-hand. The in-ground pool design included the latest cleaning system, new LED lighting, a variable-speed pump motor, and interconnection to smart-home Wi-Fi systems. This article reviews the National Electrical Code (NEC) requirements that apply to underwater LED luminaires installed in swimming pools.

NEC Article 680 includes the general rules for pools in Part I and specific requirements for permanently installed swimming pools in Part II. Section 680.20 clearly indicates permanently installed swimming pools must comply with Parts I and II of Article 680.

Section 680.23 addresses underwater lighting for pools. The first requirements address whether ground-fault circuit-interrupter (GFCI) protection is required for the luminaire and associated circuit. Section 680.23(A)(8) clarifies the GFCI requirements for the luminaire circuit. The low-voltage luminaire is supplied through a listed low-voltage transformer that is either an isolation-winding type or one that includes a system of double insulation. GFCI protection is not required on the 12-volt (V) AC side of the transformer supplying the luminaire as long as the output does not exceed the low voltage contact limit as 680.2(1) defines.

Section 680.23(A)(5) addresses underwater luminaire location and requires the luminaire be at least 4 inches below the normal water level and not more than 18 inches below the normal water level. As far as servicing the luminaire for maintenance or replacing lamps, Section 680.23(B)(6) addresses the minimum length of the cord. The rule indicates all wet niche luminaires must be removable from the pool. This is accomplished by equipping the luminaire with enough cord length to remove it from its niche underwater and lift it to the deck or other dry location without having to enter the water.

Wet niche luminaires

Wet niche luminaire requirements are in 680.23(B), which addresses wiring for the luminaire that is installed in either a metallic forming shell or a nonmetallic forming shell. It also addresses the issue of installing an 8 AWG solid or stranded copper bonding conductor for metallic forming shells. The metallic forming shell must be bonded to the equipotential bonding grid covered in Section 680.26. The bonding connection within a metallic forming shell must be encapsulated in a listed potting compound to protect the connection from the deteriorating effects of pool water. The listed cord assembly with the wet niche luminaire must include an insulated copper equipment grounding conductor not smaller than 16 AWG.

In this installation, new LED technology is being supplied by an isolation transformer having an output voltage below the low-voltage contact limit of 15V AC. In this particular installation, the use of a nonmetallic forming shell eliminates the need to bond the forming shell. Section 680.26(B)(5) relaxes the bonding requirement for listed equipment that does not require bonding, such as LED underwater luminaires with nonmetallic wet niche forming shells.

The electrical industry is evolving. New equipment is developing quickly and is not only more efficient to install and maintain, but it also is often an increase in personnel safety. Employing new technologies for swimming pool installations is a definite safety enhancement in aquatic environments, such as when used in swimming pool applications. Decreasing voltage levels below the low-voltage contact limits through listed low-voltage transformers diminishes shock hazards and eliminates the requirement for installing GFCI protection, thus reducing expenses. Using nonmetallic forming shells with listed LED wet niche luminaires (as compared with traditional metallic forming shells) eliminates the requirement for bonding to the equipotential bonding grid; therefore, removing a bonding connection to a metallic forming shell and the bonding connection creates vulnerability to the deteriorating effects of pool water.

Using variable-speed pool pump motors and controlling them through energy management systems and smart building technology reduces the expense of pool operation and maintenance. The internet of things relates to many types of electrical utilization equipment, appliances, electronics, and so forth that are all connected to and controlled through the internet in some way. Swimming pools are only one of many types of equipment and new technologies that are connected to it.

About the Author

Michael Johnston

Executive Director of Standards and Safety, NECA

Michael Johnston is NECA’s executive director of standards and safety. He is a member of the NEC Correlating Committee, NFPA Standards Council, IBEW, UL Electrical Council and NFPA’s Electrical Section. Reach him at

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