How to Install Underground Electrical Wiring for Outdoor Lighting

Installing underground electrical wiring for outdoor lighting allows you to illuminate outdoor spaces beautifully and safely. Proper installation requires planning and adherence to electrical codes to ensure the wiring is durable and hazard-free. Here is a step-by-step guide to installing underground electrical wiring for outdoor lighting:

Planning the Outdoor Lighting Layout

Careful planning is crucial before digging any trenches or installing wiring. Here are some key steps:

Determine Where You Want Lighting

Think about what areas you want to illuminate. Popular choices are pathways, patios, gardens, driveways, and entrances. Mark the approximate locations with stakes or spray paint. Consider how the lighting will be used - for safety, accenting features, highlighting plants, etc.

Choose the Type of Lighting

Common types of low-voltage outdoor lighting include:

• Path lights - Illuminate walking paths
• Step lights - Built into edges of steps and paths
• Deck lights - Shine upwards to illuminate a deck
• ** Flood lights** - Provide a wide spread of bright light
• Accent lights - Spotlight certain plants, trees or architectural features

Select lighting appropriate for each space. Check product specs for brightness, spread, and weather-durability.

Create a Lighting Plan

Draw a sketch of the house and yard indicating fixture locations. Space lights appropriately - 10-15 feet for path lights, closer for step lights. Mark where the transformer will go. Plan the wiring route from the transformer to each light fixture.

Ask Utility Company to Mark Underground Lines

Call 811 before digging to get underground pipes, wires, and cables marked for free. This prevents accidentally digging into buried utilities.

Buying Materials

Purchase all the materials needed for the project:

• Low-voltage lighting fixtures - Match voltages of all fixtures
• Low-voltage wiring - Outdoor-rated, in appropriate gauge
• Transformer - Converts household power to 12V or 24V, sized for total wattage used
• Outdoor-rated wire connectors
• Conduit piping - Houses wiring underground
• Junction boxes - For wire connections
• Shovels, trencher - For digging trenches
• PVC cement and primer - For securing conduit
• UX grounding rod and clamp - Grounds the system

Review electrical codes for specific requirements. Buy extra materials in case of errors.

Digging the Trenches

Digging trenches properly prevents damage to wiring:

• Dig trenches 12-18 inches deep. Deeper if crossing sidewalks or driveways.
• Make trenches follow direct routes between light locations.
• Smooth out trench bottoms so wires rest flat without stress.
• If soil is rocky use a pick to loosen compacted areas.

Note: Hire a professional trenching service for long or tricky runs.

Installing the Conduit

Conduit piping protects wires underground:

• Cut conduit to appropriate lengths using a hacksaw.
• Lay conduits end-to-end in trenches.
• Clean and sand cut ends so joints fit snugly.
• Glue conduit joints together using PVC cement. Allow time to dry fully.
• Cap ends of conduits until ready to run wires.

Tip: Extend conduits 6 inches above ground where lights will be installed.

Running and Connecting the Wires

Low-voltage outdoor wiring is easy to install:

• Run wiring down each conduit path, leaving excess at each end.
• Pull wires gently to avoid damage. Use a fish tape if needed for long runs.
• Install a junction box if there are multiple runs. Connect wires using wire nuts.
• Attach wiring to fixtures as per manufacturer instructions.
• Connect transformer to power supply and to light fixture wires.

Caution: Make sure no wires are pinched or near sharp edges.

Securing the Conduits and Fixtures

The final steps involve securing all components:

• Position each fixture and shine light where desired. Mark placement.
• Bury conduits in trenches so wires are fully covered.
• Attach light fixtures securely at marked locations.
• Test lights to ensure proper operation.
• Install a grounding rod per electrical code to ground the system.
• Fill in trenches completely to protect conduits. Tamp down soil.

Safety Tips

Follow these tips for safe installation:

• Turn power OFF at breaker before starting. Check wires with a voltmeter.
• Wear safety goggles and gloves when digging and installing.
• Avoid digging near gas lines. Call utility company if unsure.
• Keep children and pets away from work area.
• Use fiberglass ladder when mounting fixtures overhead.
• Call electrician if unsure of any wiring steps.

Proper planning, quality materials, and safe installation methods will lead to an outdoor lighting system you can enjoy for years to come! Let the beautiful nights begin.