How to install an exterior electrical outlet

Updated February 21, 2017

Installing outdoor outlets provides you with power for extra lighting for evening barbecues or to run garage tools for a yard project. Be sure to install a GFCI (Ground Fault Circuit Interrupter) to add protection and turn the power off if there is ever a problem. Install the outlet in a moisture proof box to keep the outside elements and moisture from getting to the electricity and shorting out the circuit.

Locate an indoor outlet close to where you will want to mount the exterior outlet. Turn the power off to the indoor outlet at the main circuit panel.

Using the screwdriver, remove the screw holding the cover plate onto the outlet. Remove the two screws that hold the outlet in the electrical box. Pull the receptacle out of the electrical box as far as the wiring will allow. Do not disconnect any of the wiring.

Using a screwdriver, twist out, knock out or punch out holes in the back of the electrical box. This will allow you to run a cable to the outdoor box.

On the outside, find a good location that's in the same wall cavity as the indoor outlet, and is clear of any internal wall plumbing. Measure about 18 inches from ground level to where the box will be mounted. Mark that measurement.

Place the box against the exterior wall and line up the bottom of the box with the mark on the wall from Step 4. Using the pencil, trace around the outside of the electrical box to make a template on the wall.

In the centre of the template tracing on the wall, make a mark in the centre. Using the drill, drill a 3/4-inch hole on the mark. This is where the cable will be pulled through to the outside outlet. If the exterior wall is make of brick or concrete, you must use the masonry drill bit.

If your style of outdoor outlet box is to be installed inside the wall where the outlet cover is flush with the wall, you'll need to use the hand saw (if masonry, use the hammer and chisel) to cut out the hole along the traced template to form a tight hole to install the electrical box.

Pending the style of box, mount the outdoor electrical box either on the wall or inside the wall using the screwdriver and the screws included in the kit.

Run a length of cable from the inside electrical box through its hole, then through the hole in the outdoor electrical box. Leave about 10-to-12 inches of extra wire at each end to work with, then cut off any excess wire.

Using the wire strippers, strip the about 1 inch of insulation from the end of each wire, both inside and outside. You will have three wires on each end: black (hot), White (neutral) and bare copper (ground).

Looking at the back of the GFCI outdoor outlet, use the screwdriver to make the following connections. Connect the black wire to the brass line screw, the white wire to the silver line screw, and connect the bare copper wire to the green/ground screw at the bottom of the outlet.

Using the screwdriver and included screws, mount the outlet inside the outdoor electrical box. Mount the insulated cover plate to the outlet box using the screws and screwdriver. This will keep rain and moisture out of the box.

From the interior outlet, attach the new cable to the existing outlet using the screwdriver and the following pattern. Connect the black wire to the brass screw, the white wire to the silver screw and the base copper wire to the green screw.

Push any extra wire back into the electrical box and wall, then mount the indoor outlet back into its electrical box using its original screws. Reattach the outlet cover to the outlet.

Turn the power back on at the main circuit breaker. Using the voltage line tester, test both the indoor and outdoor outlets to ensure they are wired correctly. Insert the red probe into one side of the socket and the black probe into the other. If the light comes on, the outlet is working properly. Repeat this test on the remaining outlet.


Never attempt to work on any electrical lines without first turning off the power. Be sure to check with a licensed electrician before doing any electrical work. Be sure all electrical work meets the codes for your local area. Follow the manufacturer's guidelines for your particular model electrical line tester, and make sure that your fingers do not touch any part of the metal ends of the probes while inserting them into the socket.

Things You'll Need

  • GFCI outlet
  • Outdoor electrical box kit
  • Screwdriver
  • Drill
  • 3/4-inch wood drill bit
  • 3/4-inch masonry bit (if needed)
  • Hammer (if needed)
  • Chisel (if needed)
  • Wire cutters/strippers
  • Length of electrical cable
  • Needle nose pliers
  • Hand saw
  • Electrical tape
  • Wire nuts
  • Utility knife
  • Tape measure
  • Electrical line tester
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About the Author

Billy Brainard graduated with a Bachelor of Science degree in education from Trinity College. As the department chairman he was responsible for creating and writing the curriculum for 7-12 grade students. Currently he writes for eHow and works part time helping employees by creating and writing resumes to help in their job search.