How to Safely Bury Electrical Wires for Outdoor Lighting
Installing outdoor lighting can enhance the beauty and security of your home. However, improperly buried electrical wires can be hazardous. Here is a step-by-step guide on how to safely bury electrical wires for outdoor lighting projects.
Choosing the Right Wire
When burying electrical wires, you need to use wire that is rated for underground use. The most common options are:
Direct burial cable - This type of cable is designed specifically for direct underground installation. It has a tough protective jacket that resists damage. Direct burial cable is available with different wire gauges.
UF cable - Also known as underground feeder cable. It has an insulating jacket that stands up to wet locations. UF cable is generally less expensive than direct burial cable.
For most small outdoor lighting projects, I recommend using 12-gauge or 14-gauge direct burial cable. This provides sufficient capacity for multiple lighting fixtures.
Digging the Trench
Once you have the correct cable, the next step is to dig a trench to bury the wires. Here are some tips:
Make the trench 12-18 inches deep. This protects the wires from being damaged by lawn equipment.
Follow a straight path between the lighting fixtures and your power source. Avoid sharp bends or kinks in the cable.
If you cross any hardscape, dig at least 6 inches below to prevent damage.
In grassy areas, dig a narrow trench just wide enough for the wire. Limit disturbance to your lawn.
Use a flat shovel to carve out clean edges in the trench bottom so the wire lays flat. Remove any sharp rocks or sticks.
Running and Burying the Cable
Once your trench is prepped, it's time to install the wiring:
Leave 2-3 feet of extra cable at the beginning and end to allow for connections.
Gently lay the cable into the trench without pulling, twisting, or sharply bending it.
Position multiple wires side-by-side with space between them. Do not overlap.
To cross hardscape, run the cable through Schedule 40 PVC conduit. This protects the wire.
In grassy areas, carefully backfill and tamp down soil regularly over the wire. Do not damage insulation.
At hardscape crossings, backfill with sand or soil without rocks. Tamp it down carefully.
To complete the project:
At connections, coil extra wire to prevent pulling/tension.
Attach wire ends using approved underground connectors. Ensure tight, waterproof connections.
Test that each light turns on before backfilling at endpoints.
At endpoints, install extra protection such as PVC pipe or an underground box.
Restore the area to match surroundings when finished. Dispose of any leftover wire.
By following these safe burial techniques, your underground wiring will be secure for many years of reliable service. Take it slow and be cautious when digging, running, and burying the cable.
How deep should I bury the electrical wire?
12-18 inches deep is the recommended depth. This prevents damage from lawn tools or other activity on the surface.
Can I bury Romex or standard electrical wire?
No, you should only use wire rated for direct underground use like UF cable or direct burial cable. Other types will fail when wet.
What kind of connectors should I use?
Use watertight connectors approved for underground connections, like DirectburialWirenuts or DryConn Direct Bury Connectors. Wrap with electrical tape for extra protection.
How can I run wire under a sidewalk or driveway?
Use Schedule 40 PVC conduit to protect the wire when passing under any hardscape.
Should I bury the wire in a conduit?
In grassy areas, conduit is not necessary if you bury the cable at the proper depth. But conduit provides an extra layer of protection.