Low Voltage Transformers

Exterior Landscape Lighting for Outdoor Fixtures

What is a low voltage transformer?

A low voltage transformer is an electrical device that transforms 120 volts (line voltage) into 12 volts or 24 volts (low voltage).

Conventional low voltage transformers, also called magnetic low voltage transformers, can be extremely large and heavy, consisting of an iron core and two sets of wires. An electronic low voltage transformer, on the other hand, also contains an electronic device, called an inverter, which allows the size of the low voltage transformer to be substantially smaller. An inverter and a small transformer make up the main components of what we normally call an electronic low voltage transformer.

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 a harmless 12-volt current. Low-voltage wiring is lightweight and can be set 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 greater, but you may need to hire a pro for part or all of the installation.

Please note: 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.

Example of How to Size your Transformer: 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, so as a general rule of thumb, you will need to select a transformer that can supply a wattage of 25% or more than your fixtures require. Therefore, you'll need at least a transformer that can handle about 90 watts. In this case, a 100 watt transformer would be the recommendation. 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 require further adjustment of the wattage required by your low voltage transformer.