How to Install Outdoor Ground Lights | Step-By-Step Project Guide

Installing outdoor ground lights involves choosing between solar, low-voltage, or line-voltage systems, calling 811 to mark underground utilities, trenching at the correct depth, and testing the system before final burial.

Running power to outdoor lighting sounds like a major project, but most homeowners handle it in a weekend. The real work happens before you touch a shovel: matching the system to your yard, sizing the transformer, and making that one call that keeps you out of trouble. Here’s how to get through it without the second dig.

Pick Your System: Solar, Low-Voltage, or Line-Voltage

The three types differ in cost, difficulty, and code requirements. Solar lights need no wiring but depend on sun exposure. Low-voltage (12V) is the standard DIY route — safe to cut, shallow to bury. Line-voltage (120V) demands conduit, an 18-inch trench, and an electrical permit before you backfill. Your choice dictates everything else, so settle this first.

Preparation: The One Step Nobody Skips

Before any digging, call 811 — the North American One Call service — at least 24 hours ahead. They will send utility locators to mark gas, electric, water, and communication lines on your property. Skipping this is the most common mistake in landscape lighting and the one that turns a weekend project into a repair call or a hospital visit.

Once utilities are marked, unpack your fixtures and check the total wattage against your transformer’s capacity. If you’re adding a 150-watt string of lights to a 100-watt transformer, the system will dim immediately. Add up the fixture wattages before you wire anything, and plan for a transformer that covers your load with a 20% buffer.

Low-Voltage Installation: The Standard DIY Route

Low-voltage is what most homeowners choose. The wire is safe to handle when cut, and the trench is shallow enough to dig with a flat shovel. Here is the order that works every time.

1. Mount the transformer near a GFCI outlet, on a post or the house wall. Do not plug it in yet.
2. Trench the path at 3 inches if it will be covered by mulch, or 6 inches for bare ground. Run UF-B or CL2 cable along the trench, leaving slack at each fixture location.
3. Connect the main run to the transformer: one wire to the COM terminal, the other to the 12V or 15V terminal.
4. Splice fixture leads to the main run using brass barrel connectors (much more corrosion-resistant than the plastic ones most kits include). Space splices at least 10 feet apart to avoid voltage drop.
5. Test before burying — turn on the transformer and walk the yard. Every fixture should light. Adjust the aim at night when you can see the beams.
6. Bury the wires only after confirming every connection is solid and dry. Wrap each connector in electrical tape or a heat-shrink sleeve for moisture protection.

For a complete selection of tested fixtures that match the wattage and voltage you need, check our roundup of the best outdoor ground lights for 2025 — they include the transformer sizes and connector types that save the most headache.

Line-Voltage and Solar: When to Go Another Way

Line-voltage is for permanent, high-output setups. Turn off the main breaker first. Dig the trench 18 inches deep and lay PVC conduit with solvent-welded joints for a watertight seal. Connect the wire to a GFCI circuit breaker, and call the local electrical inspector before burying anything. This route requires a permit in almost every US jurisdiction.

Solar lights are the opposite — no trench at all. Set them in sun for 12–14 hours to charge the battery, stake them 2–4 inches from walls or walkways, and aim them at night after dark. Some newer models connect via Wi-Fi or Bluetooth to a smartphone app for scheduling, but the basic installation stays the same: sun, stake, test, done.

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