Lights in and around a swimming pool are an essential safety feature. If we swim at night, we need to illuminate the contours of the pool itself, plus the pool deck and patio area as well as any stairs and walkways. All electrical components used around water must be properly grounded to prevent electrical shock, and lights are certainly no exception. While pool lighting is generally safe to use, it must always be installed and serviced by a professional, licensed electrician.
The biggest potential for danger comes from the light in the pool itself since it is underwater and directly connected to the household current. Therefore, an underwater pool light must be manufactured to specifications, without defects, and connected by an electrician according to code. A watertight housing with proper gaskets in a grounded niche powered with a working GFCI breaker is perfectly safe. Ground fault circuit interrupters, or GFCIs, automatically turn off the power if water touches any electrical component. The power receptacle or junction box should be at least 18 inches above the waterline and at least three feet away from the light. The junction box or receptacle must be waterproof and childproof.
The potential danger is in worn components which may leak or crack, improper installation, faulty wiring, and insufficient grounding safeguards. Over time, due to constant exposure to water and chemicals, underwater lights can eventually fail. After a few decades, the gaskets, electrical cords, and metal components of a light are bound to deteriorate. Therefore it is essential to have your pool lighting periodically inspected, especially if you have an older pool.
Never make modifications to a pool light or its components. The power cords should never be spliced or repaired. When replacing a bulb, use the manufacturer’s suggested replacement and reseal with a new gasket. If you are uncertain about the age or condition of your underwater pool light, or are unsure about how to safely replace the bulb, call a licensed electrician or a pool service company. Engineers have put decades of experience into making underwater lighting as safe as possible. The danger generally comes from a failure to maintain the equipment or unprofessional service or installation.