How to Install a Low Voltage Landscape Lighting System?

How to Install a Low Voltage Landscape Lighting System?

After you have decided what features you want to highlight, sketched the layout on a notepad, and purchased a landscape lighting kit and/or lighting fixtures, cable, transformer (power pack), and connectors, it’s time to install your lights.

Before digging though, you should call 811 to have your utility company mark the location of any underground wires and pipes before you dig. Even if you think there is nothing underground to worry about, it’s better to be safe than sorry. The service is free, so go ahead and use it to avoid any dangerous and expensive surprises.

Step 1: Layout the Components 

You first step is to lay out all of the components of your system – the light fixtures, connectors, cable, junction box, and transformer in the exact locations you wish to place them.  By doing this you can quickly identify any missing any parts, and make last-minute changes in the positioning of the lights.

Avoid placing fixtures in areas where they may be damaged by mowers, traffic, or water. When you have laid it out and confirmed you have all of the necessary components, you can begin installation.

Step 2. Install the Transformer 

Mount the transformer in a watertight box to the side of the house, garage, or a post that is near an outside ground fault circuit interrupter (GFCI) outlet.  The transformer will be plugged in permanently, so be sure to replace the standard electrical outlet cover with a “while-in-use” cover.

If you don’t have an outdoor GFCI outlet, you will need to have one installed by a licensed electrician. Don’t attempt this yourself unless you are trained in line voltage electrical circuits. If you have a transformer with a timer and built-in photocell, mount the transformer toward the west where the sun sets, so that your lights don’t come on earlier than necessary.

Now, connect the cable to the transformer. With a wire stripper tool, strip about an inch of the rubber insulation from a length of 10-gauge cable. Slip the stripped ends of the wires under the two terminal screws on the bottom of the transformer. Tighten the screws to hold the wire securely in place.

Step 3: Run the Cable 

Lay the electrical cable on the ground, following the line of light fixtures.  When you come to an obstacle such as a fence, tree, or shrub, just run the wire underneath or around it.  Make a 10 to 12 inch loop at each fixture so you will have enough extra wire for connecting the fixtures later.

Once you have everything laid out, move the light fixtures to the side so you can dig a trench for the cable. The trench only needs to be a few inches wide and no more that 3 inches deep in non-lawn areas. For lawn areas, the cable should be at least 6 inches deep to avoid damage when you aerate the lawn.

Lay the cable in the trench, and cover it with soil.  Remember to leave an excess loop of cable sticking up out of the soil near each fixture.

The total wattage of all the fixtures will determine the maximum number of lights that can be connected to the system. If the transformer is 100-watt, then the total wattage of all light fixtures must not exceed 100 watts. For example, 10 garden lights with 10-watt bulbs = 100 watt.

Use the chart below to determine the correct size cable needed based on the length of your runs.

Total Transformer Wattage  150 watts
 16-gauge cable
 200 watts
 14-gauge cable
 300 watts
 12-gauge cable
 88 watts  100 ft.  125 ft.  150 ft.
 121 watts  100 ft.  125 ft.  150 ft.
 200 watts  100 ft.  125 ft.  150 ft.
 300 watts  100 ft.  150 ft.  200 ft.
 600 watts  100 ft. x 2  150 ft. x 2  200 ft. x 2

* Note: Be aware that if you do a straight-line “daisy chain” installation, there will be voltage drop along the line that will cause each light to dim progressively to the point of being unusable. Because this, you should not install any more than two or three fixtures in a single straight line daisy chain configuration.

You can reduce voltage drop on a single line by using higher gauge wire for longer distances and/or higher combined wattage. For example, you can use 14-gauge wire for the lights of systems of less than 200 watts and 125 feet, and 12-gauge cable for systems that are more than 200 watts and 150 feet.  See above chart.

You can also minimize the voltage drop by using a junction box to centralize the voltage load. Run one wire to the junction box at the center of the zone and branch out additional wires to reach each light fixture within the zone. Doing this will distribute the voltage load more evenly among the lights.

Step 4.  Connect the Wire

Next, connect the wires to your light fixtures with weatherproof wire connectors or wire nuts.  These are generally twist-on wire nuts that are filled with silicone sealant that create a watertight connection.  This will protect your wires from the elements and make them last longer, saving you a lot of work later.

Step 5: Install the Light fixtures

Set all the light fixtures into position, checking to make sure they’re equally spaced.  Dig a hole in the ground for the fixture’s stake.  Do not use a hammer to drive the fixture into the ground, as it can damage it.

Use both hands to push the fixture and stake into the ground until the top of the stake is flush with the ground.  Tuck the cable and connector under the sod and cover them with soil, at least 2 inches deep.  Continue installing the remaining fixtures in the same manner until all are in place.

Step 6: Test the System  

After all the wiring is completed, plug in the transformer and check to see that all the lights are working. If none of the bulbs light up, you may have a faulty transformer or outdoor electrical outlet.

If lights seem dim, test the voltage level of each light fixture with a digital voltage meter.  A voltmeter can be purchased at Amazon.com or any electronics store for just a few dollars, and is a good investment, which use on other projects or repairs you may do later.

Lights should receive 10 to 12 volts each for consistency and to avoid premature burnout. If you get readings below 10 volts, there may be a bad connection somewhere, or you may have too many lights on the circuit. Recheck all connections and make adjustments as necessary until lights are working properly.

Congratulations on Successful Installation of Your Lights!

That is really all that there is to installing a low voltage landscape lighting system.  Within just few hours  time, and without the use of an expensive electrician, you can install lights along your walkway and shrub bed areas that you will enjoy for many years to come.  Installing low volt landscaping lights is one of those weekend projects that any do-it-yourselfer can be proud of.

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