Outdoor Lighting Wiring: Low Voltage vs Line Voltage Systems

Outdoor lighting transforms a home’s nighttime curb appeal and provides security and safety. But the two main wiring approaches — low voltage (12V) and line voltage (120V) — have very different installation requirements, costs, and capabilities. Choosing the right system for your project depends on fixture type, desired brightness, and DIY ability.

Low Voltage (12V) Landscape Lighting

Low voltage landscape lighting is the most popular choice for path lights, accent lights, and garden lighting. A transformer plugged into a standard outdoor outlet converts 120V to 12V. Landscape wire (12/2 or 10/2 direct-burial rated) runs from the transformer to each fixture. The low voltage is safe to touch, making it a good DIY project. Transformers typically range from 100W to 600W, and all fixture wattages on a zone must not exceed the transformer rating.

Line Voltage (120V) Outdoor Lighting

For high-brightness fixtures, large post lights, security floodlights, and string lights at significant distances, line voltage (120V) is required. Line voltage provides consistent brightness regardless of wire run length — a common problem with long low-voltage runs. All 120V outdoor wiring must use weather-resistant, in-use rated receptacles, and all outdoor circuits require GFCI protection.

Wire Burial Depth Requirements

The NEC requires different burial depths depending on circuit type and conduit use:

• 12V landscape wire: 6 inches minimum burial
• 120V direct-burial cable (UF-B): 12 inches minimum
• 120V cable in PVC conduit: 6 inches minimum
• 120V cable in metal conduit: 6 inches minimum

Voltage Drop in Low Voltage Systems

Voltage drop is the biggest limitation of low voltage systems. As wire runs get longer, voltage drops, causing fixtures farthest from the transformer to be dimmer. Use heavier gauge wire (10 AWG vs 12 AWG) for long runs, or use a multi-zone transformer with runs no longer than 100 feet per zone. Keep individual fixture wattage as low as possible (LED fixtures minimize this problem significantly).

Smart Outdoor Lighting

Both low voltage and line voltage outdoor systems can be integrated with smart controls. Smart landscape lighting transformers (Kichler, Hampton Bay) support app control and scheduling. Smart outdoor outlets and smart switches work for 120V systems. For new installations, pre-wire conduit for future expansion.

Calculate voltage drop for outdoor runs. Use the Voltage Drop Calculator on electricalcalcpro.com to ensure adequate voltage reaches all fixtures on long outdoor wiring runs.