How Is Outdoor Lighting Wired and Powered? A Houston Guide

Before anything else, place your project in one of these three columns.

The confusing part is that the fixtures themselves give nothing away. A path light on a 12-volt system and a path light on a 120-volt circuit can be the same shape, same finish, same height. The difference lives behind them, in what feeds the fixture.

Brightness pushes you toward line voltage. Twelve volts can only carry so much power before the wire gets impractical. A security floodlight covering a driveway usually wants 120 volts.

Distance works the same way. The further from your house the run goes, the harder low voltage becomes.

Permanence is the third factor. Low-voltage fixtures move easily when you change the landscaping. Line-voltage fixtures are fixed in place.

Follow the power from your house out to the last fixture. Five steps.

The outdoor outlet. Everything starts at a GFCI-protected exterior receptacle. That protection is required, and it is what shuts power off if moisture reaches something it should not.

The transformer. This box takes 120 volts and steps it down to 12. Most plug into that outlet. Some get hardwired instead, which is licensed work.

The cable. Direct-burial low-voltage cable runs from the transformer out through your yard. It gets buried shallow, because 12 volts carries far less shock risk than 120.

The connections. Each fixture ties into that cable with a waterproof connector. Silicone-filled or heat-shrink types seal out moisture. This is the part that fails first when it is done cheaply.

The fixtures. Path lights, spotlights, well lights, and step lights all tap the same run.

One number decides whether the system works. Your transformer has to be rated for more wattage than all your fixtures combined. Add them up before you buy. Running a transformer at its limit shortens its life and leaves no room to add lights later.

One safety point most guides skip. Low voltage does not mean no fire risk. A loose or corroded connection at 12 volts still generates heat, and that heat still has to go somewhere. Good connectors and correct wire sizing matter here as much as anywhere else.

Line voltage means your outdoor lights run on the same 120 volts as everything else in the house. No transformer, no stepping down.

That power comes from a circuit in your electrical panel. Sometimes an existing circuit has room. Often it does not, and the job includes running a new one.

What the wiring requires:

• Outdoor-rated wiring methods. Underground feeder cable, or standard conductors run inside conduit
• Burial deeper than low voltage. How deep depends on the wiring method, the voltage, and what the run passes under. Code sets it, and it is not one number
• GFCI protection on outdoor receptacles
• Weather-resistant receptacles with in-use covers — the bubble style that stays closed with a cord plugged in
• Wet-location rated fixtures and junction boxes. Damp-location rated is not the same thing and will not hold up here

You want line voltage when brightness matters. Security floodlights, driveway lighting, post lamps at the street, and anything covering real distance.

The tradeoff is permanence. These fixtures are wired in place. Moving one later is an electrical job, not an afternoon with a shovel.

Every part of this is licensed electrical work. It requires a permit and an inspection, and the circuit gets shut off while it happens.

This is the most common complaint about landscape lighting, and it is almost never a bad bulb.

Electricity loses voltage as it travels down a wire. The further it goes, the less arrives. On a 12-volt system there is not much to lose, so the effect shows up fast. Your first fixture gets close to a full 12 volts. Your last one might get nine.

Nine volts through a lamp designed for twelve produces a dimmer, yellower light. Homeowners replace the bulb, get the same result, and assume the fixture is bad.

Two things control it.

Wire gauge. Heavier cable has less resistance, so less voltage is lost along the way. Undersized cable is the most common cause of a dim run.

Wiring layout. This matters more than most people realize:

• Daisy chain. Each fixture connects to the next in a line. Simplest to install, worst for voltage drop. The last light is always the dimmest.
• Hub. Fixtures branch out from a central connection point. Uses more cable, but every fixture sits a similar distance from the transformer. Brightness stays even.
• T method and loop. Variations that split the load in different directions to balance the run.

Layout also decides how easy your system is to change later. Adding three fixtures to a hub is simple. Adding them to the end of a long daisy chain makes the dimming worse for everything already on it.

Plan the layout before the trench gets dug. Rewiring later costs far more than doing it right once.

Most outdoor lighting runs on its own. The control usually lives inside the transformer.

Photocell. A small sensor reads the light level and switches on at dusk, off at dawn. It follows the seasons by itself, so nothing needs adjusting when the days get shorter.

Timer. Runs on a clock you set. Reliable, but you will be resetting it a few times a year as sunset moves. In Houston that shift is more than two hours between June and December.

Combination. On at dusk by photocell, off after a set number of hours. This is the setup most people end up happiest with. Lights come on when it gets dark and shut off at bedtime.

Motion sensors. Best for security lighting rather than landscape lighting. You want a floodlight to react to movement. You do not want your path lights flickering on every time a cat crosses the yard.

Smart controls. App or voice control, scheduling, and scenes for different areas. Useful if you want different zones behaving differently, or control while you are away.

Six local conditions decide how long your system lasts.

Our clay soil does not sit still. It swells with rain and shrinks in drought, and anything buried in it moves along with it. Flexible low-voltage cable handles that shifting well. Rigid conduit runs take more stress, and connections at both ends feel it over time.

Then there is water. Fixtures in low spots spend real time submerged after a heavy rain. Wet-rated housings handle that. Cheap connectors do not, which is why connection quality decides the lifespan of a system more than fixture quality does.

Humidity works on everything else. Metal connections corrode faster here than in a dry climate. A corroded splice raises resistance, dims the run, and eventually opens up entirely.

Irrigation lines are the surprise on most Houston jobs. Sprinkler systems run through nearly every yard here, usually at a shallow depth. Trenching for lighting cable finds them constantly, and repairing one is a bad way to start a project.

Lawn maintenance does more damage than storms do. Edgers along bed lines and aerators across the yard cut shallow-buried cable every season. Mapping the runs and keeping records of where they go saves you later.

Storm season adds the rest. Debris, standing water, and the question of where your transformer sits. A transformer mounted low on a wall in a spot that floods is a problem waiting for the right week in September.

The line is clearer than most articles make it sound.

A low-voltage kit is a legitimate weekend project. Plug in the transformer, lay the cable, connect the fixtures. Plenty of Houston homeowners do it well.

The moment anything touches 120 volts, that changes. New outdoor circuits require a permit and an inspection.

Call 811 before you dig. Every time, even for shallow low-voltage cable. It is free, and it gets your gas, water, and utility lines marked before a shovel goes in the ground. Hitting a gas line in your own yard is a serious day.

Even on a low-voltage job, an electrician earns their fee in three places. Sizing the transformer for what you have now and what you will add later. Designing the layout so the far fixtures stay bright. And routing cable to survive edgers, aerators, and your sprinkler system.

On an outdoor lighting consultation, we walk the property, check your existing outdoor circuits and their capacity, plan the layout around voltage drop, and tell you which parts need a permit.

Our electricians are state licensed and background checked. We have wired Houston homes since 2003, and we pull permits and handle inspections on every job that needs them.