VOLTAGE 12V vs 120V - Pool lights are designed to operate with 12V or 120V. In some areas of the country the local code requires a low voltage 12V light while in other areas it is fine to use a 120V light. Before installing a light, find out what your local code require. If you install a 12V light you will need to install a transformer to convert the 120V house voltage to 12V. If you are replacing an existing light and do not know your voltage you may try the following techniques to find this information: 1.) Look on the face of the light bulb for the voltage rating. 2.) Look to see if you have a transformer wired before the light. If you have transformer then you have a 12V light. 3.) Check the back of the light housing where the cord connects into the light, there will be a label specification of your light. The brightness of a 12V and 120V will be the same. Some manufactures do not recommend using a 12V light if the cord of the light is going to be longer than 100' feet because you may have a voltage drop. Note: Brightness, discussed more below, is a function of light wattage not voltage. The brightness of a 12V or a 120V light will be the same.