Outdoor Landscape Lighting - March 18, 2009
Jeff Schalau, Associate Agent, Agriculture & Natural Resources
University of Arizona Cooperative Extension, Yavapai County

Arizona’s warm summer evenings are often the best time to enjoy relaxing outdoors. Outdoor landscape lighting increases safety and security around the home and can also extend the ambiance of interior living spaces at night. The specific design of a lighting system will be influenced by a variety of factors including site characteristics, scope and function of the landscape, budget, and homeowner preferences. There are a myriad of different outdoor lighting fixtures available. I would recommend using low-voltage electric lighting that is hardwired rather than the seemingly convenient solar fixtures. The solar light fixtures are dim and do not hold up to Arizona’s harsh environment for more than a season or two.

Many types of fixtures are available. Uplights are placed at ground level and aimed upward to highlight focal points in the landscape, such as specimen trees, signs, and architectural features. Downlights are placed above an object or area and aimed downward to imitate natural lighting such as simulating moonlight or for providing security to an area. Backlights are placed behind artistic objects or plant material to cast a silhouette on a wall for a striking effect. Backlights and downlights should be placed to hide the light fixtures from view. Pathlights are placed just above grade level along sidewalks, driveways, or informal paths in the landscape to safely lead a person from one location to another. Specialty lights are used to accent landscape features or create moods.

Some preplanning will be needed to install wiring sleeves (conduit) under sidewalks, in raised beds, and other isolated elements such as water features. However, you should only put in outdoor lighting after all other landscaping elements have been installed. This will allow you to see all the aspects of your design and how outdoor lights will accent them. Also, make your lighting system flexible enough to change as your plants grow.

You should always begin with a site plan drawn to scale. Include the house, other structures, driveway, walkways, steps, large trees, specimen plants, garden beds, etc. Select the focal points such as the entrance, a large tree, water feature, or other interesting feature. Select no more than two focal points and add them to the plan. Next, select the high traffic areas, such as driveways, walkways, decks, and steps that need to be illuminated. To determine the desired lighting and effects needed for these areas, use a flashlight to explore fixture locations and illumination effects.

There are also safety and permitting considerations. Before digging, call Arizona Blue Stake (800-STAKE-IT). Arizona Blue Stake will contact utility companies which will respond by placing color coded markings or clearing the area if not underground utilities are present. In most cases, this can be done in two working days. Check with your local municipality to determine if a permit is needed and to locate property line easements. A licensed electrician should be employed to wire an outdoor receptacle and/or switch to control the new lighting system and may also be needed to establish a circuit and install the fixtures for outdoor flood lamps.

Most residential outdoor lighting uses a 120-volt outlet or circuit as an electric source, which is converted to a much safer 12-volt system through the use of a transformer. Most systems can run multiple fixtures off the same wire. Twelve-gauge double wire is standard, but 10-gauge and 8-gauge wires are used when resistance is a problem due to long wire runs or too many fixtures. Transformers come in various sizes and are installed in conjunction with a controller that switches the lights on and off. Follow manufacturer recommendations to determine transformers and wire needed based on the fixtures and their locations.

There is much more to learn about outdoor landscape lighting. There are books available on lighting design and manufacturer’s catalogs that describe fixtures and wiring configurations. For more information and resources, consult the University of Minnesota Publication Designing and Installing Outdoor Lighting available on-line at: www.sustland.umn.edu/implement/outdoor_lighting.html.

The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at cottonwoodmg@yahoo.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/.

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Arizona Cooperative Extension
Yavapai County
840 Rodeo Dr. #C
Prescott, AZ 86305
(928) 445-6590
Last Updated: March 10, 2009
Content Questions/Comments: jschalau@ag.arizona.edu
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