Landscape Lighting Wiring: Layouts, Cable Sizes and Voltage Drop Explained
How to wire low voltage landscape lighting: daisy chain, T, loop and hub layouts, transformer taps, cable gauge by length and load, voltage drop, burial depth and mixing LED with halogen.
Key points
- Low voltage landscape systems run 12–15 V from a transformer; cable size and layout decide whether every light gets enough voltage.
- Daisy chain is simplest but causes the most voltage drop; T, loop and hub layouts balance voltage better.
- Use thicker cable (10–12 AWG) for long or heavily loaded runs and keep loads well within the transformer rating.
- LED fixtures draw far less current than halogen, which reduces voltage drop and allows longer runs.
Most problems with low-voltage landscape lighting come from wiring, not fixtures. Lights at the end of a run glow dim, connectors corrode, transformers overload. With the right layout and cable size, a system runs evenly for years. This guide explains the principles.
How a low-voltage system works
A transformer converts mains voltage to about 12–15 V. It is plugged into an outdoor outlet with an RCD or GFCI, or hard-wired by an electrician. From its low-voltage terminals, direct-burial cable runs through the garden to each fixture. Each fixture connects to the cable with a waterproof connector. A timer or photocell on the transformer switches the system.
Because the voltage is low, the current is high for a given power. A 240 W load at 12 V draws 20 A. High current means the cable’s resistance causes a noticeable voltage drop along each run.
Voltage drop in plain terms
Voltage drop depends on:
- Current (the load on the run)
- Cable length to each light
- Cable size (thicker cable, lower resistance)
As a rough guide at 12 V, 30 m of 12 AWG cable carrying 100 W loses about 1 V. Halogen lamps dim visibly and lose life below about 10.5 V; overvoltage above about 12.5–13 V shortens their life. LED fixtures usually accept a wider range, often 9–15 V, but very low voltage can still cause flicker.
Wiring layouts
Daisy chain (straight run)
One cable runs from the transformer past each light in turn.
- Pros: simplest, least cable
- Cons: largest voltage drop at the end; first lights get more voltage than the last
Fine for short runs with few LED fixtures.
T layout
A feed cable runs from the transformer to the middle of the group, then splits into two branches.
- Pros: the voltage drop is shared, so lights get more even voltage
- Cons: a little more cable and a junction to make
Loop
The run leaves the transformer, passes all lights and returns to the same terminals.
- Pros: each light is fed from both ends, so voltage is very even
- Cons: more cable; polarity must be kept consistent
Hub (star)
A feed cable runs to a hub point, where several fixtures connect on equal-length leads.
- Pros: very even voltage within each group, few buried joints, easy fault-finding
- Cons: more planning; needs a hub connector or junction
Professional installers often combine hub and T layouts.
Cable sizes
| Cable | Typical use (12 V) |
|---|---|
| 16 AWG (about 1.5 mm²) | Short runs, a few LED fixtures |
| 14 AWG (about 2.5 mm²) | Short to medium runs |
| 12 AWG (about 4 mm²) | Most residential runs up to about 30 m |
| 10 AWG (about 6 mm²) | Long or heavy runs, feed cables to hubs |
| 8 AWG | Very long feeders in large gardens |
Use cable rated for direct burial, and keep each run within the rating of the transformer output it is connected to.
Transformer sizing and taps
- Add up the wattage of all fixtures on the transformer
- Choose a transformer with about 20–25% spare capacity
- Multi-tap transformers have outputs at 12, 13, 14 and 15 V; use higher taps for longer runs so the far lights receive about 11–12 V
- Spread runs across outputs so no single run is overloaded
Measure the voltage at each fixture with all lights on, and adjust taps or layout until all are within range.
LED changes the numbers
LED fixtures use a fraction of halogen’s power: a 4–7 W LED spotlight may replace a 35–50 W halogen. That cuts current and voltage drop dramatically, allows smaller transformers and longer runs. When upgrading a halogen system to LED, the existing cable usually becomes more than adequate. Check that the LED fixtures are rated for AC input and compatible with magnetic or electronic transformers as used.
Avoid mixing halogen and LED on one run if possible; the voltage suited to one may not suit the other.
Burial and routing
- Bury cable about 15 cm deep in beds and lawns, deeper under paths in conduit
- Avoid areas that are dug often, and keep away from irrigation pipes where possible
- Run cable in conduit under paving and drives, with spare capacity for future runs
- Leave a loop of slack at each fixture so it can be moved
- Record cable routes on a garden plan
Connections
Use sealed gel-filled or crimp-and-heat-shrink connectors and keep joints few and accessible. Our guide to landscape lighting wire connectors compares the types.
Safety and codes
The mains side of the transformer must be protected by an RCD or GFCI and installed to local electrical codes, often by a licensed electrician. The low-voltage side is generally safe to work on, but the high currents mean poor connections can get hot. Never exceed the transformer’s rating.
Planning a system step by step
- Sketch the garden and mark each fixture with its wattage
- Group fixtures into runs of similar length and load
- Choose a layout (T or hub for most runs)
- Calculate load and length per run and pick cable sizes
- Size the transformer with spare capacity
- Install, then measure voltage at each light and adjust
For an overview of the whole system, see our low voltage landscape lighting guide, and for the installation process, landscape lighting installation.
Fixtures for projects
We supply LED landscape spotlights and floodlights, in-ground uplights and garden lights for hotel, campus and public garden projects. Tell us your system voltage and layout, and we will confirm suitable fixtures.
Sources
Frequently asked questions
How do you wire landscape lighting?
A transformer plugged into an outdoor outlet or hard-wired by an electrician converts mains to 12–15 V. Direct-burial cable runs from its terminals to the fixtures, which connect to the cable with waterproof connectors. Layouts such as T or hub runs keep voltage even.
What gauge wire for landscape lighting?
Commonly 12 AWG for runs up to about 30 m and loads up to around 150–200 W at 12 V, and 10 AWG for longer or heavier runs. Short, light runs can use 14 or 16 AWG. LED loads allow smaller cable or longer runs.
Why are my landscape lights dimmer at the end of the run?
Voltage drop. The further the light is from the transformer and the heavier the load, the more voltage is lost in the cable. Use thicker cable, a higher transformer tap, a T or hub layout, or split the run.