Landscape Lighting System: Complete Wiring Guide
Bill of materials
Low-voltage landscape lighting operates at 12V or 24V AC from a step-down transformer. NEC Article 411 governs these systems. The transformer needs a GFCI-protected 120V outlet. On the low-voltage side, wire gauge depends on total wattage and run distance - voltage drop is the main concern. Use 12 AWG for runs up to 100 feet and 10 AWG beyond.
Low-voltage landscape lighting per NEC 411 requires GFCI for the transformer primary. Burial depth for low-voltage cable is only 6 inches. Size the transformer at 120% of total fixture wattage. Use hub-and-spoke layout to equalize voltage.
Transformer circuit
| Component | Specification | NEC basis |
|---|---|---|
| Wire (copper) | 14 AWG THHN | Table 310.16, 110.14(C) |
| Breaker | 15A double-pole | 240.4 |
| Voltage | 120V single-phase | |
| Conduit (EMT) | 1/2" EMT | Chapter 9 Table 4 |
| GFCI | Required (GFCI breaker or device) | 411.4(A) |
| Max distance (3% VD) | 229 ft at 120V copper | 210.19(A) Note 4 |
Installation notes
This project requires GFCI protection per NEC 411.4(A). The simplest approach is a GFCI breaker at the panel, which protects the entire circuit. For 240V circuits, use a 2-pole GFCI breaker sized to match the circuit. GFCI breakers cost $40-80 depending on amperage.
Standard 120V circuits use NM-B cable with 14/2 cable (hot, neutral, ground). For conduit runs, pull individual 14 AWG THHN conductors. All connections must be made in accessible junction boxes.
Run length matters: every foot of wire adds voltage drop, reducing power to your equipment. The table below shows the exact voltage drop at common distances. If your run exceeds the 3% threshold, upsize one gauge.
Voltage drop by distance
Percentage voltage drop at common run lengths. NEC recommends 3% maximum for branch circuits and 5% for combined feeder plus branch.
| Distance | 14 AWG Co | 12 AWG Co |
|---|---|---|
| 25 ft | 0.3% | 0.2% |
| 50 ft | 0.7% | 0.4% |
| 75 ft | 1.0% | 0.6% |
| 100 ft | 1.3% | 0.8% |
| 150 ft | 2.0% | 1.2% |
| 200 ft | 2.6% | 1.6% |
Common products for 14 AWG Copper circuits
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Related wire data
Detailed ampacity: 14 AWG copper. Wire size lookup: 15A circuit. Calculators: voltage drop · panel load calculator.
Frequently asked questions
What wire size do I need for landscape lighting system?
Use 14 AWG copper or 14 AWG aluminum on a 15A breaker at 120V. This is based on NEC 2023 Table 310.16 ampacity with 110.14(C) termination limits and 125% continuous load sizing per 210.19(A)(1).
Does landscape lighting system require GFCI?
Yes. GFCI protection is required per NEC 411.4(A).
NEC 2023 references verified April 2026