300 Watt Direct Burial Transformer - AL300BW

Exterior Landscape Lighting for Outdoor fixtures

Low-voltage, systems have several advantages for the home owner:  Most important, low-voltage equipment is easier to install.  Except for the transformer that's connected to a 120-volt circuit, the entire system runs on harmless 12-volt current. Low-voltage wiring is lightweight and can be laid on the ground or buried just below the surface.   Another advantage of low-voltage equipment is that it can be relatively inexpensive. And, when you do the job yourself, the bottom line for low-voltage looks even better. Not only can the capital outlay for a standard high-voltage system be much greater, but you may need to hire a pro for part or all of the installation.

You must size your low voltage transformer to match the combined wattage of the lights or lamps to which the transformer is to supply power plus approximately 25% more for the line.   

Sizing your Transformer Example:  If you buy a system that comes with six fixtures and each fixture has a 12 watt lamp, then you have a minimum need of 72 watts  (12 x 6 = 72).   The line itself degrades the wattage as well so as a general rule of thumb you will need to increase it by 25% more.     Therefore you'll need at least a transformer that can handle about 90 watts.    So a 100 watt transformer would be the minimum needed.   If you plan to add additional fixtures in the future, you may want to increase the  wattage of the transformer or purchase additional transformers as needed.   Keep in mind that the voltage drop over long distances is more pronounced in a low-voltage system, therefore, using wire that's too light (skinny) can affect the output at the lamps and this may adjust the wattage need of your low voltage transformer.