How To Install PVC Conduit Underground

Posted on: 3 October 2017

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If you need power to an outbuilding, run electricity using PVC conduit and existing circuits to hide the cables. PVC conduit is easier to install than metal conduit, and the only difficult part is digging the trench. You don't need advanced electrical skills, but it requires patience and attention to details. Install PVC conduit underground by following these steps. 

Prepare to Install the PVC Conduit

To install the conduit. gather:

  • work gloves
  • wheelbarrow
  • metal stakes cord or twine
  • shovel
  • five-pound sledge hammer (optional)
  • drill and drill bits suited for the material 
  • PVC cement
  • PVC cleaner 
  • PVC couplings 
  • PVC cutter 
  • PVC conduit

Before you dig, you will need an electrical permit from your building codes department, and keep it posted until you install the conduit. Get the utility companies to map out pipes and gas lines in your yard, which is commonly provided free.

Dig the Trench

Mark the area to install the conduit with metal stakes hammered in at ten-foot intervals and rope or cord to keep the path straight. Only mark one side of the trench, so digging will be easier. 

Dig a trench two-feet long and one foot wide, saving dirt in a wheelbarrow for backfilling. The National Electric Code requires conduits be buried at least eighteen inches on private property. In some jurisdictions, you may need to contact an inspector after you dig to ensure the trench meets codes.

Drill Holes and Lay the Conduit

Mark the position for a hole where the conduit needs to enter the building, using a suitable drill bit for metal, brick. or wood. If the building is concrete, make the holes with a sledge hammer. Also, drill the holes on the building supplying the power.

Dab some PVC cleaner on the exterior the conduit ends, add PVC cement while the cleaner is still wet, and  connect the ends with the couplings. Rotate the connection several times to spread the cement, and let it sit a minute or two before connecting the next conduit.

When you get to the other building, run it through the drilled holes. Connect it to the electrical panel following manufacturer instructions, and use the pipe cutter saw to trim the end piece to fit. If you don't have a PVC pipe cutter, cut it with a hacksaw, but PVC cutters give a smoother edge than a saw. 

Back fill the trench with the dirt you dug earlier, or what the code requires, and test the connections. If you need an electrical box installed, or the connections fail, contact an electrician, such as at Morris Electric Contracting & Service, Inc.