Quick Summary
A drawing comes before any cable, recording fixture positions, distances, wattages, and everything the run has to cross on the way. Transformer placement near the center of the run cuts cable cost, and its 120-volt supply is licensed work under branch circuit rules. Wire gauge follows from distance, branch wattage, and the voltage the furthest fixture needs, since a thin run leaves a permanent defect underground. Hub layouts hold output steady across a group where a daisy chain guarantees a decline from first fixture to last. Low voltage runs are allowed six inches of cover, connections need listed direct burial devices, and aiming happens after dark.
Fixtures get all the attention, and the cable does all the work. A yard can hold beautiful hardware and still disappoint the moment the far end of the run goes dim or a connection floods after the first storm. Texas soil, summer heat, and heavy irrigation put every buried component under steady pressure. Anyone researching how to wire landscape lighting quickly finds that the decisions worth getting right happen before a single fixture comes out of the box. Here is what the job involves and why each choice carries weight.
Mapping the Run Before Any Cable Leaves the Spool
Every decision downstream depends on a drawing made first. A scaled sketch of the property records where each fixture sits, how far it stands from the transformer, and what the cable has to cross on the way, whether that is a driveway, a bed, a lawn, or a tree root system. Fixture wattages get written onto that same sketch, since the total governs the transformer and the individual figures govern the branches. Irrigation lines, buried utilities, and future planting all belong on the drawing too, and locating services beforehand is not optional on any property. The plan also settles how many circuits the system needs, which is far harder to change once cable is in the ground. An hour spent on the drawing saves a day of trenching later.
Where the Transformer Belongs and Why
Placement of the power supply shapes the layout that follows. The unit needs a weather-rated location on an exterior wall or a post, mounted at a height that keeps it clear of standing water and accessible for later service. Distance to the fixtures drives everything, so a position near the center of the run costs less cable than a spot tucked around a corner for appearance. Feeding it requires a 120-volt supply with the protection the branch circuit rules call for, and that connection sits firmly in licensed territory. Capacity should exceed the connected load with room left over, since owners add fixtures within a season or two. Multi-tap units earn their price on properties where one long branch needs a higher output than all the rest.
Matching Cable Gauge to the Distance Involved
Skimping here is the quiet mistake that undoes an otherwise good design. Resistance rises with length and with load, and a run sized too thin delivers a fixture less voltage than it needs, which shows as a dim, warm, short-lived lamp at the far end.
Three figures settle the calculation:
The distance from the transformer.
The total wattage on that branch.
The voltage a fixture requires to perform as designed.
Heavier wire costs more per foot and solves the problem permanently, whereas a thin run leaves a defect buried under a lawn. Direct-burial-rated cable is the only appropriate choice, since indoor wire fails quickly in wet ground. Splitting one long branch into two shorter ones often beats stepping up a gauge.
Hub Layouts Against a Single Daisy Chain
How the cable branches determines whether the last fixture matches the first. Running one line from fixture to fixture is the quickest arrangement and the one that guarantees a decline, since every unit along the way takes its share before the next one sees anything. Bringing a single heavy cable to a central junction and feeding several fixtures outward from that point equalizes the distance to each, which keeps output consistent across the group. A large property needs more than one of those junctions, positioned so no branch stretches unreasonably far. Adding a fixture later is straightforward on the second arrangement, since the junction already exists and only a short run is needed. The planning shows up in how the yard looks two years on.
Trenching, Cover Depth, and Cable Protection
Everything buried has to survive years of soil movement, irrigation, and yard equipment. Low-voltage runs at thirty volts or less are allowed six inches of cover, though a listed system’s own instructions can permit a different depth, and the 120-volt supply feeding the transformer sits considerably deeper. Depth alone is only part of it, since a shallow run under a lawn meets an aerator or an edger eventually. Routing along bed edges, fence lines, and hardscape borders keeps cable away from the tools that damage it. Anywhere the run crosses a driveway or a walkway, a sleeve protects it and leaves a path for replacement without breaking concrete. Photographing the trench before backfill gives you a record that nobody ever regrets having.
Connections, Testing, and Final Aiming
Joints are where most systems fail, and they fail slowly enough that nobody connects the symptom back to the cause. Listed, gel-filled, direct burial connectors are what hold up in wet soil, where a twist on a connector wrapped in tape corrodes through a season. Once the run is complete, voltage gets measured at the first fixture and at the last, and readings outside the fixture’s rated window mean something in the design needs correcting before backfill. Aiming happens after dark and never before, since a beam that looked right at noon rarely lands where you expected it to. Final adjustments take an evening of walking the property and moving heads a few degrees at a time until each one lands.
Getting the Wiring Right the First Time
None of this work shows once the sod goes back down, which is exactly why it so often gets skipped. A system that still performs in year five was sized, routed, and connected with that year in mind, and no fixture on the market compensates for a shortcut underneath it. The primary side is licensed work regardless, so the real question is whether the rest gets the same standard.
Aaron’s Electrical Service installs low-voltage landscape lighting throughout the Houston and Dallas-Fort Worth areas, handling the transformer, the primary circuit, the buried runs, the connections, and the after-dark aiming as one job. Our licensed electricians also install outdoor receptacles, security and parking lot lighting, EV charger circuits, and whole-home surge protection. All of our work is permitted and carries a lifetime workmanship warranty.
Planning a system for this season? Call us at 281-719-0464 in Houston or 469-998-0097 in Dallas-Fort Worth to get the design started properly.
FAQs
When should I hire a licensed electrician for low-voltage lighting?
The fixtures run at 12 volts, but the transformer connects to a 120 volt branch circuit that has to be sized, protected, and located under the applicable rules. Buried runs carry cover requirements and connections need listed direct burial devices. A licensed electrician handles the primary side and the permit, which is where the real exposure sits.
What gauge cable should a run use?
It depends on three things, which are the distance from the transformer, the total wattage on that branch, and the voltage the furthest fixture needs to perform. Longer runs and heavier loads both call for thicker wire. Undersizing shows up as dim, warm lamps at the far end and cannot be fixed without digging.
How deep should the cable be buried?
Runs at thirty volts or less are allowed six inches of cover, though a listed system’s instructions can specify otherwise, and the 120-volt supply sits deeper. Depth is only half the answer. Routing along bed edges and using sleeves under paving protects cable from the aerators, edgers, and shovels that actually cut it.
