If you want to add an exterior light, water fountain, or some other feature to your yard, you'll need a power source. Forget the bulky extension cords and learn how to run underground power cables.

4 Outdoor Light Images

External power sources are handy, but oftentimes they're located within a few feet of the house. This design is helpful when hanging patio lights, but not much more. If you want to add a permanent electric feature farther out in your yard, consider running outdoor cable. 

To run outdoor cable, first consider the type of conduit you'll need. Some building departments require metal or plastic conduit for all underground wiring, but most codes call for conduit only where the wiring is exposed or in a shallow trench. Condensation can moisten wiring in watertight conduit, so underground feeder (UF) cable offers the only protection against water damage.

Before you dig, check local building codes. Some allow a shallower trench if the cable or conduit is covered with a 2X6 pressure-treated plank. Also make sure to have utilities mark underground lines. In the United States, call 811 to be connected to your local One Call center.

Once power is brought outside, you'll need about 8 to 12 hours to dig trenches, run 60 feet of cable, and install lights. If you need to dig more than 50 feet of trench, rent a powered trench digger to speed up the job. 

What You Need

  • Shovel
  • Posthole digger
  • Hammer
  • Drill
  • Fish tape
  • Pliers
  • Garden hose or sledgehammer
  • Conduit and fittings
  • Conduit clamps
  • Stakes
  • String line

Step 1: Plan a Route


After the utilities have marked the location of any underground lines, plan a route that stays several feet away from them. Use string lines and stakes to indicate the path for the underground cable.

Step 2: Dig a Trench


Cut the sod carefully with a square-bladed shovel so you can replace it later. Dig a trench deep enough to satisfy local codes. If you encounter a large root or rock, consider running the cable under it.

Step 3: Run Conduit


Run metal conduit under the sidewalk and attach a protective bushing to each end. Push the UF cable through the conduit.

Step 4: Feed Cable


Unroll the cable carefully to avoid kinks. Have a helper feed it through the conduit as you thread it through the trenches all the way to the power source.

Step 5: Attach Cable to Fixture


When running cable to a lamppost, be sure to set the post so its access hole faces the trench. Carefully push the cable into the access hole and up the body of the post.

More Tips for Running Outdoor Cable

How to Route Under a Sidewalk


To run cable under a sidewalk, screw a length of pipe onto the end of a garden hose. Poke in the pipe, then turn on the water. Push until you meet resistance, then pull out the pipe to flush the hole. Repeat until you get to the other side. Leave the pipe in place and run cable through it. Or flatten the end of a piece of conduit and drive it under the walk.

How to Run Wires through Metal Conduit


If codes call for a continuous run of metal conduit, purchase watertight boxes and fittings. Take care to tighten each fitting; one bad connection can result in water leakage. Then run wire through the conduit using a fish tape.


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