SIZING YOUR TRANSFORMER
Your transformer will plug into your home’s 120v system and converts the power down to 12v, feeding your power through your wiring and making your lighting system safe to install and use. It is important to make sure you are choosing the ideal size based on your installation needs.
Simply put, each light in a landscape lighting system will use roughly 2-5 watts. To be safe and make it simple, you can just assume each light will use 5 watts. So, for example, let’s say you have a system with 10 lights. You simply take 5 x 10 to get your wattage which gives you 50 watts.
However, the general rule is you want your transformer to be 20% more than the maximum wattage, so that same 50-watt lighting system would require a 60-watt transformer.