Bistro Lights: Decorative or Dangerous? Determine the legality and hazards of the installation

Shutterstock / Cerama_Ama / Lenapolll
Shutterstock / Cerama_Ama / Lenapolll
Published On
May 14, 2021

I have noticed a disturbing trend over the past year. I feel a professional—and moral—responsibility to address what may be a dangerous installation of decorative backyard lighting. I totally understand that a person can tackle do-it-yourself projects in their own backyard, especially if the projects are easy and not too technical.

Unfortunately, some people are intent on buying and spending an afternoon installing lighting kits without contacting an electrical contractor or inspector to determine the legality and possible hazard of the installation.

If I witness something that I feel is dangerous and happen to know the property owner, I will call the person’s attention to the hazard and explain why it is unsafe. Most electrical contractors and electrical inspectors do the same, but we can’t contact everyone who may unknowingly be putting themselves, their families and friends at risk.

A prime example of an increasingly common backyard lighting trend is “bistro” or string lighting that is designed to be strung from the patio or back of the home to a tree or strategically placed pole in the yard. The power source for these lights can be low-voltage, using a plug-in 120V to 12V power (lighting) transformer.

An alternative power source is a full 120V, using a cord cap plugged into a special-type receptacle. Where a plug-in transformer or a 120V cord cap is used to connect the string lights and is installed outside in a wet location, receptacles of 15 and 20A at 125V must have a weatherproof enclosure, whether or not the attachment plug is inserted.

Where a transformer is used, either it must be weatherproof or have a weatherproof cover large enough to totally contain the transformer while maintaining its weatherproof design. Any receptacles installed outdoors with a weatherproof cover must be a special weather-resistant-type receptacle (have rubber boots designed into the receptacle to minimize water intrusion).

Take care when doing electrical wiring of any kind around any swimming pool. Any electrical conductors, such as power, communications or network-powered broadband systems installed over a swimming pool must comply with 680.9 in the National Electrical Code. Table 680.9(A) provides height clearance requirements for overhead conductors. An insulated power cable at 0–750V to ground, supported on and cabled together with a solidly grounded bare messenger cable or a solidly grounded neutral conductor, must have at least 22½ feet of clearance in any direction to the water level, the edge of the water surface, base of a diving platform or permanently anchored raft.

Where any electrical power conductors, other than the cables covered above, are installed above the swimming pool, the height restriction is 25 feet for 0–15,000V. The electrical cable assemblies and conductors must be 22½ feet high for the first application or 25 feet high for the second application for a minimum horizontal distance of 10 feet from the inside edge of the pool. The dimensions in the table usually address service or feeder conductors.

The purpose of these limitations is to ensure that energized conductors and cables will not be reachable with the long metal pole on a tool used for skimming and cleaning the pool or from anyone using a diving board or other structure who could inadvertently pull the electrical cable or conductors into the pool. Swimming pools are designed to provide an electrical equipotential plane surrounding the pool to ensure that no one can be exposed to a debilitating or incapacitating electrical current.

Where a lighting system is installed in outdoor areas above swimming pools, 680.22(B)(1) states that luminaires and lighting outlets installed above the pool or the area extending 5 feet horizontally from the inside walls of the pool shall be installed at a height of not less than 12 feet above the maximum water level of the pool.

GFCI protection is required by 680.22(B)(4) for lighting outlets installed in the area above the pool and between 5 and 10 feet horizontally from the inside walls of the pool. Low-voltage luminaires located in close proximity to the pool must not exceed the low-voltage contact limit of 15V sinusoidal, 21.2V peak for nonsinusoidal, 30V continuous DC, or 12.4V peak for DC that is interrupted at a rate of 10–200 hertz pulsating DC.

Installing string and other lighting outside, especially near or over a swimming pool, can be tricky. A licensed electrical contractor will do a safe and NEC -compliant installation.

About the Author

Mark C. Ode

Fire/Life Safety, Residential and Code Contributor

Mark C. Ode is a lead engineering associate for Energy & Power Technologies at Underwriters Laboratories Inc. and can be reached at 919.949.2576 and

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