How to Wire Landscape Lighting | Low-Voltage Made Simple

Landscape lighting wires to a low-voltage transformer plugged into a GFCI outlet, with fixtures connected along a buried cable run and tested before backfilling.

For the full breakdown, see our best 12/2 Landscape Wire guide.

Wiring landscape lighting is one of the easier outdoor projects you can take on, because the whole system runs on just 12 volts — safe enough that no electrician is required. The principle is straightforward: a transformer steps house current down to low voltage, a single cable carries that power to every fixture, and waterproof connections tie it all together. Do the layout first, hook everything up, test the run, then bury the cable. That testing-before-burying step is the one most people skip, and it’s the one that saves you from digging everything back up.

What You Need Before You Start

A low-voltage landscape system has four main parts: the transformer (often called a power pack), the low-voltage cable, the fixtures themselves, and waterproof connectors. Most kits ship with fixtures and a transformer, but you’ll usually buy the cable separately — and the gauge matters.

The low-voltage power unit wire should be 12–18 AWG underground low-energy circuit cable or SPT2W. For runs under 100 feet, 12-gauge cable is the safe default — it carries current with less voltage drop than thinner 14- or 16-gauge wire. If you’re covering a larger yard, step up to a heftier conductor rather than stretching a thin one.

How to Wire the Transformer and Cable

Mount the transformer on a stable surface near a GFCI-protected outdoor receptacle, following the manufacturer’s clearance and mounting-height instructions. These packs need airflow, so don’t tuck one into a corner where heat builds up.

Once the transformer is mounted, run the main cable from it toward your first fixture. Keep the transformer unplugged until every connection is complete.

Many kits use quick-connect systems—the cable snaps into place with a piercing connector. Others use permanent splices with butt connectors and heat-shrink tubing. Either works; just make sure every connection is rated for outdoor use. A regular wire nut in the dirt is a failure waiting for a rainy season.

Connecting Fixtures and Managing Voltage

Leave about 18 inches of slack at each fixture for connections and adjustment. That extra loop gives you room to work, and it lets you reposition a fixture slightly after the cable is buried.

Use watertight connectors or wire nuts rated for outdoor low-voltage connections. This is the step where systems fail, because a loose or unsealed splice lets moisture in and corrodes the connection over a season or two.

Most fixtures are wired in a daisy chain from the transformer: the main cable runs to the first fixture, then on to the next. That spacing keeps voltage healthy along the run.

If your transformer has multiple voltage taps, start on the lowest one — usually 12V — and only move up if you measure low voltage at the farthest fixture. LEDs run hot on overvoltage, so don’t bump the tap up unless the lights actually need it.

Testing, Burying, and Common Pitfalls

Before you bury anything, plug the transformer in and verify every fixture lights properly. Check brightness at the farthest fixture — if it’s dim, the cable is too thin or the run too long, and fixing that now is a five-minute job. Once the cable is buried, it’s a dig-it-up job. Unplug the transformer before servicing anything, and let hot fixtures cool before handling them.

The most common mistakes are all avoidable:

• Plugging in the transformer before all connections are secured.
• Using non-waterproof connectors outdoors.
• Burying the cable before testing the full run.
• Ignoring fixture-specific instructions on connector type or polarity.
• Overloading the transformer — keep the connected load at about 80% of capacity or less for headroom.

When it comes to the cable itself, a quality 12-gauge run makes everything else easier.