How to Install Outdoor Landscape Lighting

Walk your yard at dusk and identify what you want to light — pathways, garden beds, trees, architectural features, or dark security zones. Sketch a rough map showing the house, walkways, and plantings, then mark where each fixture will go. Group fixtures into separate wire runs of no more than 100 feet each to minimize voltage drop. Count the total wattage of all fixtures (e.g., 10 LED path lights at 3W each = 30W) and add 20% headroom to determine transformer size — in this example, a 45W or larger transformer.

Choose a location for the transformer that's close to a GFCI-protected outdoor outlet and hidden from view — behind a shrub, under a deck, or on the side of the house. Mount it at least 12 inches above grade to keep it away from standing water and splashing. Most transformers have a built-in mounting bracket with keyhole slots — drive two screws into the wall stud or use masonry anchors on brick, hang the transformer, and tighten. Do not plug it in yet.

Unroll the 12-gauge landscape wire from the transformer location along each planned run, laying it on the surface of the lawn or bed — do not bury it yet. Leave 2-3 feet of extra wire at the transformer end and 6-8 inches of slack at each fixture location for easy connections. Pin the wire loosely to the ground with landscape staples every 6-8 feet to keep it in place. If you need to branch a run into a T-split, cut the wire at the branch point and use a waterproof gel connector to join the trunk and branch wires.

Set each fixture at its planned location and push the ground stake into the soil by hand or with a rubber mallet. Path lights should sit 14-18 inches above grade and be spaced 8-10 feet apart along walkways for even coverage without hot spots. Spotlights aimed at trees or walls should be positioned 1-2 feet from the base of the object being lit, angled upward at roughly 30-45 degrees. Step back after placing each fixture and check the sight lines — you want to see the light effect, not the fixture itself.

Most low-voltage landscape fixtures connect to the main wire using either snap-on piercing connectors (included with many kits) or waterproof gel-filled splice connectors. For gel connectors — the more reliable option — strip half an inch of insulation from each conductor on the main wire and from the fixture lead, insert all wires into the connector, and snap the lid shut. The gel displaces moisture and creates a weatherproof seal. Repeat for every fixture on the run. There is no polarity with 12V AC landscape wire, so it doesn't matter which conductor connects to which fixture lead.

Strip about three-quarters of an inch of insulation from each conductor at the transformer end of the wire. Open the terminal clamp on the transformer — most have two screw terminals marked "12V" (or "13V," "14V," "15V" for voltage compensation on long runs). Insert one conductor into each terminal and tighten the screws firmly with a small flat-head screwdriver. If you have multiple wire runs, each run gets its own pair of terminals or its own tap on the transformer. Start with the 12V tap; you'll adjust after testing.

Plug the transformer into the GFCI outlet and switch it on — all fixtures should light up. Wait until dusk to evaluate the actual lighting effect. Walk the entire run with a voltmeter and check the voltage at the first fixture (should read 11.5-12V) and the last fixture on each run (should read no less than 10.8V — a drop of more than 1.2V means the run is too long or too heavily loaded). If the farthest fixtures are dim, move them to the higher voltage tap on the transformer (13V or 14V) until the reading at the far end is close to 12V. Adjust fixture angles and positions while everything is still above ground.

Once you're satisfied with fixture placement and voltage, use a flat-blade spade to cut a narrow trench 4-6 inches deep along each wire run. In lawn areas, slice straight down, fold the sod flap back, lay the wire in the bottom of the trench, and fold the sod back over — the grass will heal in a week or two. In mulched beds, simply tuck the wire under 3-4 inches of mulch. Where the wire crosses a paved walkway, run it underneath through a shallow trench dug at the edge, or through a piece of PVC conduit slipped under the pavement. Backfill the trenches and tamp the soil lightly.