How to Install Low Voltage Outdoor Landscape Lighting
Low voltage landscape lighting is a breeze with the right fixtures and a plan to place them. Part 1 of our guide explains which materials you need, what kind of low voltage options you have, and a few tips on where to place your fixtures. This post is step-by-step instructions for installing your lights.
As a recap, you’ll need these materials to install your lights:
- 12-Volt landscape lighting fixtures of your choice
- 12-Volt, outdoor- rated transformer (rated for at least the total wattage of your fixtures)
- 100 feet or more of 10- or 12-gauge landscape wire (listed for direct burial)
- A square-blade shovel
There are also these optional materials, which are dependent on your lighting layout or preferences:
- A timer or photocell (if it’s not already built into the transformer)
- Weatherproof wire nuts (with sealant in them)
- Weatherproof cover for your GFCI outlet (if your transformer is a plug-in model)
- Aluminum tent stakes
- Wire clips and stainless steel screws (for mounting cables to trees)
- Weather-treated wood post for your transformer
- PVC pipes, couplers, and caps (to weatherproof connections to path lights)
Step 1 – Lay out your fixtures and landscape wire
Once you’ve chosen a place to install your transformer near your home, then key thing to remember is avoiding voltage drop. Your transformer should be centered in your layout in case you have to wire more than one line, i.e. “run”, to the transformer. Your first fixture should maintain about a 10-foot distance from the transformer to prevent it from getting too much voltage and burning out prematurely. Here are 5 general lighting layouts for landscaping:
- Series – Also known as a “daisy chain”, series is the most common layout but also the most likely to incur voltage issues. The wiring is an easy, single run with lights located along the length of the wire.
- Split – Multiple series single runs wired back to one transformer is known as a split run.
- Tee – If you need to run wire for a lengthy distance like under a sidewalk or driveway, a tee run places the transformer at the end of the center for the “T” while the legs spread out on either side. Make sure to use heavier gauge wire like 10 or 12 or a double run of wire to form the center leg of the “T”.
- Split Tee – Basically multiple tee runs, all to one transformer.
- Loop – This is a series run but instead of ending the wire at the last fixture, you arrange it so the wiring comes full circle, making a big “loop” back to the transformer. This layout can be tricky since you need to be extremely careful not to cross the wire, meaning mix up which wire end was connected to which wire on the load side of the transformer. Load side transformer wires tend to be the same color and only connections from the transformer to the main are different insulation colors to denote the hot from the neutral wire.
Multiple straight runs in several directions, a tee connection run, or a looped run are the recommended layouts to reduce voltage drop issues. Allow about three extra feet of wire as leeway for when you begin to bury or splice your wiring. String the wire under or around obstacles like fences or shrubs. Try to run wire about one foot from the edge of a sidewalk or pathway.
Step 2 – Mount the transformer
Position your transformer close to where you will connect it to the main power. Keep in mind if you need to position a photocell on the transformer then it may need to face a particular direction. You can mount the transformer to the side of your home or use a 3-foot, weather-treated wood post or 2x3 stake. The transformer should be at least one foot above ground level. If the transformer is a plug-in model, make sure your outdoor receptacle (i.e. outlet) is GFCI rated to protect against electrical shorts and covered with a weatherproof cover.
To hardwire a low voltage transformer, the main power should be turned off at the breaker panel before making any electrical connections. The transformer has at least four wires attached to it. On one side, often called “input”, there is usually a white wire and a black wire to connect to the main power or line voltage coming from your home. Always remember to connect the colors: white wire from the transformer to the white wire from the house (white is usually the neutral wire) and the transformer’s black wire to your home’s black wire (typically the hot wire). Sometimes your transformer will also have a green wire that should be attached to “ground”. The other side of a transformer is the “output” side and has two similarly colored wires, like two red or two blue wires. These wires supply power to your low voltage circuit. The polarity of these wires is not important; either wire on the output side of the transformer may be connected to either wire of the low voltage circuit. All of the main wire connections should end up inside the transformer’s outdoor-rated casing.
Step 3 – Dig trenches for wiring
Grab your flat nose or square-bladed shovel and make small trenches for your wires. That means stick your shovel perpendicular to the ground and wiggle it to create a “V” for the wire. You don’t need to pull the grass up completely. The trenches should be 3 to 6 inches deep depending on the how intensive your gardening and lawn care may be. Dig six inches deep if the soil gets turned over fairly often. Leave a small bit of slack when you get to each fixture since you’ll need to cut or connect your fixtures later. Push your wire into the trench and leave the trench open for adjustments.
Lighting Tip: As tempting as it may be, don’t use your shovel to push wires down into the trenches. You could accidentally cut the wiring completely or slice the wire insulation and expose it to electrical short-causing elements. Instead use a piece of thin plywood or your fingers to push the wire down.
Step 4 – Wire and position fixtures
Many landscape fixture sets are prewired and include snap-on or press-on connectors to connect the wiring. These connectors use sharp needlelike prongs to puncture the wiring and make contact with the wires without cutting them completely apart. This is a convenient and easy-to-install setup. However, snap-on connectors have been known to rust or fail, requiring you to dig up the wiring and make new connections. For more durable wire connections, we recommend screw-on, weatherproof wire nuts with sealant in them to keep out any moisture the seeps into the ground.
The stakes for path lights are a bit precarious with the rising and sinking ground over the seasons. Keep your path lights standing tall by using 1-1/2-inch PVC pipes, caps, and couplers to give the ground stakes of these top-heavy lights more burying depth. Wire the run from the main power through a tee coupler attached to a PVC pipe buried vertically. Remove the stake and add the cap to the base of the path light, threading the fixture’s wiring through the cap. Also cut off the snap-on connectors and strip a ½-inch length of insulation off the fixture’s wire. Connect the fixture’s wiring to the run with weatherproof wire nuts and place the all of wiring inside the PVC pipe. Cover the pipe with the cap and fixture.
Lighting Tip: Pond and fountain underwater lights are watertight and often have weighted bases to keep them at the bottom of your pond or in a certain position. They also have long cords that allow you to bury the wire connections in drier dirt along the pond’s edge. Try to keep these connections and other non-aquatic lights at least 10 feet away from your water features.
Step 5 – Bury Your Wiring
Burying your wire and tamping the soil back down should be the very last thing you do. This allows you to troubleshoot or adjust your lighting more easily. Have a voltmeter on hand to help anticipate voltage drop, especially in systems with more than 10 lights or for systems with wire runs longer than 100 feet.
Lighting Tip: The most common problems when trying to install low-voltage landscape lights are poor wire connections, too many fixtures on one transformer (i.e. overloading), and cables that are too small for the load. Double check everything!
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