DekPro Effex offers a 36-watt and a 60-watt transformer. To determine which transformer is right for your project, you need to add up the total wattage of all your deck lighting fixtures. Once you know that number then you can compare it to the max power on both of the transformers. The total wattage of your lights should not exceed 80% of the transformer's capacity, so the 36-watt transformer can power 28.8 watts max and the 60-watt transformer can power 48 watts max. The easiest way to make sure that you have everything you need to install your deck lighting would be to use the DekPro Effex Transformer Kit. The kit will include the transformer and any other cable and accessories you will need to install your lighting project.