HOW TO: Light your landscape
Want customers to see your work in a positive light? Follow these steps to enhance your landscape project with lighting.
When it comes to installing a low voltage landscape lighting system, certain tools and tips can make the difference between a professional lighting job and a slap-shot installation. Many factors influence the outcome of a landscape lighting system: correct voltage, wire sizing and placement of the fixtures. All these elements combine to give the landscape a dramatic effect that will impress your customer. Remember, the work you do today is the billboard to advertise your future jobs.
The right tools Before you begin your job, inventory your tools to make sure you have the ones that will make the job easier: wire strippers, crimper and cutter; standard hammer and/or high impact rubber mallet; screw driver (both flat-head and Philips heads #1 or #2); pointed and flat shovels; cordless drill with assorted wood and mason drill bits; flex rake and broom; needle-nose pliers; and post hole diggers (See "Recommended accessories," page 35).
Preliminary considerations 1. First, locate the power source for your transformer. You're best off using an existing receptacle located in a garage, carport, utility shed or pool enclosure. Sometimes it is necessary to use an external receptacle either on the side of the house or in the landscape. Mount the transformer one foot above the ground - near a receptacle - leaving a drip loop. Once power location(s) have been determined, it is best to plan your job on paper.
2. Make a quick sketch of the landscape to determine placement of fixtures, the lengths of your runs and total load. Once you have a rough sketch of your landscape, locate the areas you want lit and determine the wattage for each fixture. Work with your distributor or supplier to choose appropriate lights for each area. Don't forget to consider other light sources in the area (i.e., patio lights, porch lights, flood lights, security lights and street lights). A general rule of thumb is 10/1: you want the object you're lighting to be 10 times brighter than the ambient light in the area.
3. Determine voltage drop. To help eliminate voltage drop, sketch the wire runs to determine the length of the wire and calculate the load and voltage drop before you install anything. Remember, it is easier to change your sketch than it is to lay new wire after-the-fact. Use this formula to calculate the voltage drop at the end of your run (also, for tips on how to reduce voltage drop, see Figure 3, page 35):
Voltage drop is equal to:
Subtract your voltage drop from the output at the terminal block of your transformer. The result is the voltage your last fixture on the run is receiving. A one-volt drop will lead to a 25 percent drop in light output. A two-volt drop will lead to 50 percent drop in light output (see Figure 2, page 34).
Choosing a transformer To choose the right transformer for the job, use this formula (based on single run):
Voltage drop is equal to:
Number of fixtures x watts per bulb
For example, 8 fixtures x 20 watts per bulb = 160 Va., so the recommended transformer is 200 Va.
If you're using a multi-circuit transformer, you must balance the fixture wattage load and be sure to not exceed the wattage rating of a given circuit. If this happens, the circuit breaker will trip on the side that is overloaded. Simply reduce the overage of wattage by either ª moving a fixture or two on the over loaded side to the other circuit, or - by reducing the light bulb wattage of the fixtures to decrease the total wattage to the appropriate circuit rating.
Installing the system Once you know where the power is going, what fixtures and wattages you're using, the cable size and length, you are now ready to install your low-voltage lighting system.
1. Distribute the cable to the desired locations for fixtures. Selecting the right cable is an important aspect of landscape installation because voltage drop can occur, making the lights dim and yellow. Use cable/distance charts and voltage-drop calculations to choose correct cable size (see Figure 3, above).
2. Split and splice cable. Use crimp-on spade or eyelet connectors. Screw cable connectors into the terminal block on the transformer face and tighten it (see Figure 4, page 36).
3. Position the fixture in a select location for desired effect. Remember to remove brush or debris from the fixture location. It could be a potential hazard.
4. Install mounting devices. All mounting stakes can be pressed or hammered into the ground with a standard hammer or rubber mallet. Use a small block of wood that gives you a larger surface to pound. Leave a 1-inch section of stake above the ground to help isolate the metal from potential corrosions.
For in-ground installation of directional, area and path lights, find the threaded base at the bottom of the fixture and assemble it to the top of the mounting device (standard or commercial stake or canopy) by connecting the threads, pulling the lead wire through the mounting device to tighten. The fixture lead wire and connector should be buried to prevent detachment and give it a cleaner look. For a more permanent mount, set the stake in concrete or use a commercial mounting pedestal with stabilizing fins.
5. Wire the fixtures. Snap on the fixture lead wires to the main cable. You can use a quick connector or "cut-and-splice," and use wire nuts with seal tape. I recommend using a quick connector because it is easier: make a few snaps, tighten a screw and the two cables are connected. Using a cut-and-splice tool can work effectively, especially with an expert installer. However, it is a lengthy process and could lead to bad connections if not installed properly (see Figure 5, above).
6. Install bulbs. Make sure light bulbs are installed properly and are making good contact. Remember to lubricate the socket's screw shell with dielectric grease for light bulbs that are not protected by a sealed fixture.
7. Test the system. Turn the transformer on to make sure system is working properly and to see if you have good connections and all fixtures are illuminated. If one fixture is not working properly (i.e., there is no light output, a yellowish or dimmed beam), take a voltage meter and test voltage at the connection and socket. If fixtures are dim and voltage is less than 10 volts, you have excessive voltage drop. To solve this problem, move the fixture closer to the transformer or make a separate run. If not all of the fixtures illuminate, check the voltage at the transformer terminal block. If there is no voltage, check to see if the transformer is plugged in and turned on. It is also a good idea to check the voltage at the receptacle (see Figure 2, page 34).
8. Bury/hide cable. If the system is working, you can either bury the cable, hide it in hedges or tuck it under ground cover or turf. Now your client is ready to enjoy the new lighting system.
The most important step to installing landscape lighting is to take your time doing it. It's a lot easier to do it right the first time and avoid future problems than it is to backtrack and find your mistake. And it's easy to get in over your head. If you're not completely sure what you're doing, don't tackle the job by yourself - there is too much room for error. Employ a lighting specialist of electrical contractor.
Before you begin your lighting installation, make sure you have the accessories you need. These include:
- Dielectric grease to lubricate screw shell of socket to prevent bonding of the light bulb to the socket.
- Jell-filled wire nuts or quick connectors to attach fixture to main cable.
- Electrical tape if you're using wire nuts to prevent movement or loosening of connections.
- Concrete anchors #10 x 1 inch.
- #10 x 1 inch Phil pan machine screw (preferably stainless steel).
- Nail staples if you're attaching to decking, patio covers, trees or other type structures.
- 4 x 4 inch x 4 feet Redwood post for mounting the transformer next to receptacles in the landscape. (Use these wherever there is no structure on which to mount the transformer. Dig a hole and fill it in with concrete when post is set.)
- A couple of bags of pre-mix concrete (for the above use).
- Weatherproof receptacle covers to protect against shock or premature circuit breaker tripping to water access.
- Ground fault interrupter circuit (GFIC). It's a good idea to replace all outdoor receptacles with GFIC ones if you are plugging in a transformer.
- Matches or tube of silicon to seal up any exposed connections or wires.
- Extra stakes and assorted light bulbs according to what you use most.
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