Most deck lighting systems require a transformer as a powersource that converts 110-volt line voltage to 12-volt low-voltage electricity. The transformer will plug into a standard outlet and run wiring through a loop to each light fixture. Some transformers use a timer or light sensor to automatically turn the lights on at night. It is very important to purchase the correct transformer for your lighting system. Most LED lights require 12-volt DC volt transformers while most incandescent lights require 12-volt AC transformers. Check the specifications on the light fixtures before purchasing your transformer.
To determine the needed size of the transformer, you will need to multiply the number of lights by the number of watts and add 10 percent for line loss.
You will need to purchase a transformer that can supply at least 220 watts. Round this number up to the next available transformer size.