low voltage landscape lighting transformers and low voltage cable,choosing a landscape lighting system

Determining What Size Transformer You Will Need.

The transformer or power pack supplies the 12volt electricity to your lights. It should be plugged into a standard outdoor 120volt grounded outlet. The power pack converts the 120 volt power input to a safe 12volt output. All are equipped with automatic timers allowing lights to go on or off at preset times, and many are also equipped with dusk to dawn photo eyes.

The size transformer you will need is determined by adding up the total number of lights you will have in your light scheme and matching it to the correct transformer. As an Example: Let's say you have a total of eight low voltage fixtures in your landscape lighting scheme: three 50 watt halogen spot light fixtures, four 10 watt accent fixtures , and one 10 watt wall wash light fixture. OK, let’s add them up. 50+50+50+10+10+10+10+10=200 total watts. You will need a 200-watt transformer. Note: The low voltage transformers run most efficiently when you use close to the maximum allowed wattage or the exact max allowed wattage output. This means a 200-watt max output transformer powering 200 watts of total fixture load.

Next, based on the following information, you would choose the size of your low voltage cable. (The cable from the transformer connect to each low voltage fixture connector.)

Low voltage cable is weather resistant, self-sealing, insulated stranded wire. It is available in 12, 14, & 16 gauge sizes. Don’t worry, I’ll explain how to use it! If you are not familiar with wire gauges, the lower the number, the higher the capacity or total load it can carry. Example: 12 gauge low voltage cable can carry more total load compared to a 16 gauge low voltage cable.

150 watts total load use 16 gauge low voltage landscape cable
200 watts total load use 14 gauge low voltage landscape cable
300 watts total load use 12 gauge low voltage landscape cable
600 watts total load use 2 parallel runs of 12 gauge low voltage landscape cable

Generally speaking, if your cable runs are 150’ or more, you should use the large cable conductor size (12 gauge), but always follow the manufacturer’s recommendations regarding electrical requirements.

Most transformers have a very simple connection on the bottom of the unit where you terminate the cable ends. Follow the manufacturer’s instructions and any recommendations. OK! Now it's time to put it all together. Go to the Layout and Installation link.