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How To Install Electrical Conduit Outdoors


Install Electrical Conduit Outdoors


Conduit is a piping or tubing designed to enclose and protect the wires that distribute power throughout your home, outdoor lighting and other outdoor fixtures.


The types of conduit available for outdoor use include:


Rigid steel conduit, a popular method for outdoor installations where protecting conductors is essential

Rigid nonmetallic conduit, PVC schedule 40, rated for electrical use.

Flexible non-metallic conduit (liquid tight), is strong, watertight, non-corrosive and weighs less than
  flexible metallic tubing, making it a good choice for applications such as heating, air conditioning and
  outdoor lighting.


UF cable, which is waterproof wiring designed to be buried directly in the ground without a conduit, can often be used for outdoor projects. Even if you use UF cable, conduit is essential to use at points where the cable comes out of the ground and runs to the power source or fixture, or in an area where digging may occur.


This project guide will cover running rigid steel conduit from inside a basement to the outside to carry cable for powering an outdoor light fixture. For information about running electrical wiring outdoors see our Installing Landscape Lighting Project Guide


Check with your local building inspector to determine any outdoor electrical code requirements before beginning this or other outdoor electrical projects. Also check with your local utilities before digging to ensure you stay away from utility pipes and cables buried in your yard.




• Check local building and electrical codes before running outdoor conduit to ensure compliance.
• Check to see if a building permit is required.
• Check with local utilities before digging in your yard to ensure you don't dig up utility pipes and cables.
• Turn off power in the work site area.




• You don't have to turn the power off to run the conduit. However, if you plan to run electrical wire or cable
  to a new fixture at the same time you run the conduit, be sure to turn the power off to the outlet or breaker
  from which you will draw power.




• Save money by running conduit yourself.
• Save time by measuring and diagramming your project. Take the diagram with you to the store where an
  associate can help you pull the correct materials. 






Step 1: Drill a hole

Drill a hole near the inside power source

• Measure carefully both inside and outside the house before you drill to ensure 
  that the hole you drill is near the inside power source and goes through the 
  rim joist and not the foundation or first floor of the house.

• Drill a hole sized to fit your conduit through the outside wall at the point where 
  you want the wire to exit the house.


Step 2: Cut the EMT conduit to create a nipple

Cut the EMT Conduit to Create a Nipple

• Use a vise to hold the ½-inch steel EMT conduit.

• Use a hacksaw to cut a piece of steel EMT conduit to fit through the hole and 
  extend 1-inch into the inside. This short piece of steel EMT conduit is called a 

• Use a pair of channellocks to remove the burrs on the end of the EMT conduit.


Step 3: Attach the LB fitting

Attach the LB Fitting

• Install a 3/4 x ½-inch reducing bushing and a ½-inch compression connector 
  in the top hole of the LB and slide the steel EMT conduit nipple onto one end and 
  tighten with a wrench.

• Slide the conduit/LB assembly into the wall until the fitting is up against the outside 
  wall of the house.

• Check the inside to be sure it sticks out about 1-inch


Step 4: Dig a trench

Dig a trench from directly under the LB fitting to the location of the outdoor light Dig a trench from directly under the LB fitting to the location of the outdoor light. Make the trench width the width of the shovel and 24-inches deep. Keep the trench as straight as possible. Check local codes to ensure compliance.

Step 5: Cut and attach the rigid steel conduit

Cut and Attach the Rigid Steel Conduit

• Cut a piece of conduit to fit between the LB fitting and the 90-degree sweep 
  fitting that will bend into the trench using the same procedure as in Step 
  Two to cut and de-burr.

• Attach the end of the conduit to the LB fitting.

• Attach the other end of the conduit to the sweep fitting. The bottom of the sweep 
  should rest at the bottom of the trench.


Step 6: Strap the conduit to the house

Strap the Conduit to the House

• Drill a hole in the foundation just below the LB fitting to attach the rigid steel 
  conduit to the house, as needed.

• Use a masonry screw to attach the one hole steel conduit strap to the foundation.


Step 7: Seal the gaps

Apply caulk to seal the gaps Apply caulk to the gaps where the LB fitting meets the wall to make it waterproof.

Step 8: Attach a metal outlet box to the rigid steel conduit and light post

Attach a Metal Outlet Box to the Rigid Steel Conduit and Light Post

• Measure the last length of the rigid conduit to reach the location for the outdoor  
  light fixture. Cut it to length, allowing enough extra conduit to make a final 
  90-degree bend to come up out of your trench and attach to a metal wet 
  location outlet box.

• Attach the outlet box to the end of the ¾-inch rigid steel conduit with a ¾-inch 
  rigid set screw or compression connector.

• Drill a hole in the back of the outlet box and attach the box to the base of the light 
  pole using a self tapping screw.