How to Install Underground Low Voltage Landscape Lighting

Installing underground low voltage landscape lighting can greatly enhance the beauty and functionality of your outdoor spaces. With proper planning and installation, you can create a stunning and long-lasting lighting system to illuminate garden beds, accent architectural features, light pathways, and highlight trees and shrubs. Here is a step-by-step guide on how I installed underground low voltage lighting in my landscape.

Selecting the Right Low Voltage Lighting System

When choosing an underground landscape lighting system, there are several key factors to consider:

• Voltage - Low voltage systems typically operate between 12V and 24V. Lower voltage systems are safer and easier for DIY installation.

• Lamp type - Common options include LED, halogen, and incandescent. LED lights are the most energy efficient and long-lasting.

• Lumens - Lumens indicate brightness. Choose lights with enough lumens for each application. Path lights may need 20-50 lumens, while spotlights to highlight architectural features may need 200+ lumens.

• Fixture styles - Well lights shine upward and are used to highlight trees and shrubs. Path lights illuminate walkways. Flood lights aim downward to highlight walls and fences. Choose appropriate styles for each area.

• Transformer - The transformer converts high voltage power to low voltage. Select a transformer with enough wattage for all planned fixtures, plus 20-30% more for future expansion.

Planning the Lighting Layout

Carefully planning the lighting layout is a crucial step. Here are some tips for designing an effective plan:

• Map out fixture locations - Draw a to-scale map of the installation area and indicate potential fixture positions.

• Focus on key elements - Illuminate walkways, entrances, gathering areas, architectural and landscape features.

• Consider light spread - Factor in the spread of light from each fixture, avoiding excessive overlap.

• Highlight changes - Use lighting to emphasize shifts in elevation, boundaries, edges.

• Mind cable length - Plan the lighting zones so that cable runs to each fixture are within the product's limits.

Gathering Materials and Tools Needed

Before starting, ensure you have all necessary materials and tools:

• Low voltage lighting transformer and fixtures
• Outdoor-rated low voltage wiring and cable
• Wire connectors, splice boxes, terminators
• Shovel and digging tools
• PVC conduit for wire burial
• Outdoor-rated junction boxes
• Voltmeter to test system
• Personal protective equipment for digging
• Manual impact drive tool for landscape spikes

Installing the Transformer

The transformer should be installed first:

• Mount the transformer near an outdoor GFCI outlet using the included hardware. The transformer requires an unswitched 120V power source.
• Ensure the transformer is protected from weather under an overhang or inside a weather-resistant housing.
• Allow for airflow around the transformer to prevent overheating.
• Follow manufacturer instructions to properly ground the transformer.

Running Cable to Fixture Locations

With the transformer ready, it's time to run cable to the planned fixture locations:

• Use cable rated for outdoor low voltage lighting. Common options are 12 or 14 gauge PVC jacketed 2-wire cables.
• Lay out the lighting cables from the transformer to each fixture location, cutting them to proper lengths.
• Bury cables underground for concealed wiring:
• Dig trenches 12-18 inches deep along cable route using a shovel or trencher.
• Lay cables inside PVC conduit in trench to protect wire. Conduit diameter should be at least 3x the cable diameter.
• Back fill and compact soil over buried cable run.
• Above ground wiring should be protected inside PVC conduit and strapped securely along walls or posts.

Installing Light Fixtures

Once cabling is laid out, the fixtures can be installed:

• Attach fixtures to mounting stakes, ground spikes or brackets per product instructions.
• At each fixture location, dig a small hole or drive the landscape spike into the ground.
• Pull up cable and leave 12-18 inches of slack to allow for repositioning or raising of fixture.
• Make wire connections using gel-filled wire nuts:
• Connect fixture cable leads to main cable leads using like colors.
• Ensure connections are secure and waterproof by tightening wire nut and sealing with silicone.
• For elevated fixtures like path lights, tighten any adjustment knobs to secure the angle and height.

Connecting to the Transformer

With the fixtures positioned, complete the system wiring back to the transformer:

• Ensure cables are properly connected at all fixtures and terminate any unused lead wires with silicone-filled end caps.
• Route the two main cables from the last fixtures to the transformer. Leave slack for adjustments.
• Connect the cable leads to the low voltage terminals on the transformer per the manufacturer's diagram. Polarity matters, so connect like colored wires to the correct terminals.
• Turn on power and test operation using a voltmeter to verify proper voltage at fixtures.
• Make any final positioning adjustments to optimize light distribution.

Proper installation results in a beautifully lit outdoor space that adds form, function and safety for years to come! Take time to carefully plan the lighting layout and use quality fixtures with UL listing for best results.