You will find one of two types of fixtures. A swimming pool light isn’t necessary but adds to the aesthetics of your pool at night. What the pool guy will replace is the entire fixture. If you only have one pool light, try switching the pool pump on and off. Some light bulbs are expensive - in the range of $300-$400, so you might think about replacing the pool light gasket every 3 years or so. If the power is truly off, the pump won’t turn on. Tantalize your senses, sight, sound and touch. o fill pool back up. You don’t want to risk possible electrocution, so flip the pool lights on and off to make sure the pool isn’t receiving any electrical power. o Wait for it to dry, maybe dry it yourself. A pool light bulb and fixture should last for several years. Many bulbs fail because the gasket deteriorates from the heat and harsh pool chemicals. Mount the light on the pool wall according to manufacturer specifications. o Take the glass off. Be sure that the breaker, GFCI, and pool light switch are all off. At this stage I'm assuming the halogen bulb is the only thing broken (plenty of cable available also to work with for the replacement well above the waterline) so an LED replacement which can use the same transformer (which is hidden in the wall cavity) is my preference. o change the bulb. o wear some rubber gloves or outfit for safety. Besides locating the model number and the manufacturer’s name, when it comes to pool lights, pool owners tend to have two concerns, how do you turn your pool light on/off and how do you toggle between light shows? If it does not bubble, you can proceed further. most all pool lights i have changed come in a sealed unit,power cord and all,you can use the old power cord to pull the new one through,just tape it to the new one and use it as a snake to pull the new cord through,make sure you drain the pool below the pool light unless you intend on having a proff. PAL-2000 LAL Color Change LED Array W/Color Lock - PAL Lighting | 39-LA U-2CU (replaces 39-LAU).