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How to Size a and Install a Low Voltage Landscape Lighting System


The two reasons for using low voltage landscape lighting are 1) low energy consumption and 2) safety.  Low voltage lighting normally uses a transformer to convert 110 volt household current to 12 volt DC current.  There is no risk of electrical shock to children or animals.  It can take 8 to 10 hours to install for an average system and cost $450 - $600 for the system  itself.


Sizing the transformer

Multiply the number of fixtures you intend to use by the wattage each will use. The wattage of the transformer should be more than the amount of wattage needed. For example, if you are using 10 fixtures at 7 watts each, a 100- watt transformer would be enough.



The typical wiring used is 12 gauge 2 connector wiring, rated for outdoor use; however, the gauge of the wiring should depend on the distance between the transformer and the most distant light and the wattage load. A chart on wiring can be found here: http://ecmweb.com/news/electric_fundamentals_successful_lowvoltage/


Low Voltage Compared to 120 Volt Lighting

Low voltage lighting need only be hidden underground, while 120v must be buried 18” and/or placed in a protective conduit.

Low voltage lighting can be operated in wet or moist locations, while 120v wiring must be absolutely waterproof.

Low voltage lights can use small light bulbs or LEDs while 120v lamps are much larger.

Low voltage lights can be installed on an existing outdoors outlet, while 120v outdoor lighting may require a licensed electrical contractor and even a local permit.

Installing a Low Voltage System

The first step in installing a low voltage system is to determine the locations, types, number, and wattage for fixtures. Then you can select a transformer, or series of transformers, to fit the power needed. Finally, you can select the gauge and length of wire needed to connect all of the fixtures to the transformer(s). A little too much wire is, of course, better than getting too little.


After you purchase the components, law them out where they will be installed, including fixtures and wire.  Next, turn up sod to allow the wire to be dropped in the trench. Prepare holes for the posts that the fixtures will be installed upon. Make the electrical connections between the connecting wire and each fixture according to the instructions that come with each fixture. Install the fixtures. Push the sod back into place over the wire.


Some suggested on installation tips include:


  • Alternate lights on the sides of a path or walkway
  • Use upward lighting for trees and shrubs
  • Vary light and dark areas to improve visual interest for a garden

 Installation of low voltage can often be completed in a day or a weekend by the typical homeowner.