Add an Electrical Outlet to a Wall

Spreading power outlets evenly throughout a space can open up rooms and make new spaces much more friendly. Placing a new electrical outlet can help make a house more livable. With the right planning and safety precautions, running wire from a power source to a new outlet doesn't need to take more than a couple of hours. Learn to plan the job properly, run wire safely, and test your project to make sure it's secure.

Steps

Planning the Job

  1. Turn off the circuit breaker. It's absolutely essential that any time you're working with electricity you turn the current off and double-check to make sure there's no current before you start working. Always turn the circuit breaker off first, before doing anything else. Use a non-contact voltage tester to check before moving forward.
  2. Assemble the necessary tools and materials. To install a new electrical outlet and make the connections safely, you'll need a few basic electricians' tools. Make sure you have access to the following:
    • Wire strippers
    • Drywall knife
    • Drill with a wood drill bit
    • Pair of lineman’s pliers
    • Screwdriver, finishing and Philip’s head
    • Non-contact voltage tester
  3. Determine the best location for the outlet. Measure the distance off the floor to the other outlets in the building. Be aware the bottom of the cover plate is not the distance you want to measure. Turn off power in the outlet. Take off the cover plate held on by the single screw in the middle of the outlet and measure to the hole cut in the wall.
  4. Find an opening in the wall. In most homes, there are 2x4 or 2x6 studs typically at 16" or 24" increments along any wall. Outlets must always be attached to a stud for security and safety. Mark a space at the appropriate height, at a location between two studs.
    • The easiest way to locate studs if to use a "stud finder" available at many hardware stores. You can also try tapping the wall lightly with a hammer and moving slowly across the wall and listening closely. The wall will sound hollow for most of the taps and then sound "solid" when you have reached a stud.
  5. Confirm there are no other mechanical or plumbing items in the wall. Check for plumbing from sinks showers or toilets on the opposite side of the wall. Be aware of any HVAC air returns or ducts.
    • If there is a grill high up or at the bottom of the wall where you want the outlet, you can't do it with the air return in the same wall space. Explore with a nail hole and hanger. Poke a hole and use something like a wire hanger to "feel" around inside the wall cavity to check.
  6. Find out where you can get power. There are two basic ways to install a new electrical outlet, running electrical wiring from a circuit breaker to the new location, or from another outlet in the same room. Depending on where you're installing a new outlet–living space, basement, or outdoor area–access to power may vary. Find the closest and most convenient place to connect to make the job easy on yourself.

Running Wire

  1. Cut a hole in the wall near the existing power source. To open up enough space to work, you'll need to cut a 12x12 piece of drywall out of the wall near the receptacle, preferably above it. You'll also need to cut a new hole, roughly the same height, at the location where you want the new outlet. This can be somewhat smaller: 2.5-in. x {{safesubst:#invoke:convert|convert}} to account for the new cut-in box.
    • To make your cuts, use a strong utility knife and make small and firm incisions over and over until you have cut through the wall material. Walls made with plaster may require you to drill holes into the corners and cut the hole with a hole saw.
    • You also might have to cut one other hole in between two locations depending on how far they are apart. In general, you want to have access holes every {{safesubst:#invoke:convert|convert}} so it’s easier to thread the wires through the wall manually.
  2. Pull the appropriate kind of wire between the two locations. Once you have access to the locations, get your Romex non-metallic wire. For residential jobs, the appropriate size of wire is 14/2, rated for 15 amps. Give yourself a foot to {{safesubst:#invoke:convert|convert}} of wire sticking out on both ends. Wire the new receptacle first and then go back and connect the new wire to the existing circuit. Cut jacket off Romex about {{safesubst:#invoke:convert|convert}} long.
    • You should use wire that is proper for the power rating of that circuit and of the same size as the wire you are connecting too. Take a sample of the existing wire with you when you go to purchase the new wire.
  3. Install the outlet receptacle at the new end. After you run the wire between the two locations, make your connections and wrap the wire. Purchase the outlet from a store and connect the wires to receptacle. Inside the wire, there are three conductors, typically black, white, and green with no insulation. On the receptacle itself, there are two brass screws, two silver screws, and green screw. It's typically good practice to wrap the wire and connections with electrical tape, just to keep everything from touching. Screws and wire should all be wrapped.
    • The green wire should be connected to the copper wire with no insulation. Hook it around and tighten green screw down.
    • The white wire needs to be stripped ¾-inch off end of wire. Bend a hook on the end of the wire, put hook around one of silver screws and then tighten screw down. The other silver screw isn’t used.
    • The black wire goes to the brass screw. Do the same thing: strip the wire, make a hook, and tighten the screw down.
  4. Install the cut-in outlet box with the fasteners supplied. The outlet box should be firm on the wall and not be able to be wiggled around. This is used to house the loose wires and keep them wrapped and secure for safety purposes. These are available at all home repair outlets.
  5. Install the wires at the starting outlet. Go back to starting outlet and connect the wires. Take the existing receptacle and remove it from the wires, then match up the black wires with black, white with white, and ground with ground.
    • Cut an 8-inch pig-tail (stubby piece of wire) and strip off both ends 3/4s of an inch. Take all three black wires together so the ends are matched up. The end of the new wire should meet the end of the old wire, and one end of pigtail.
    • Get a wire nut (plastic cone) that just screws onto the wire to connect them. The three black wires should be able to connect with one wire nut, and the same goes for white and ground wires. Take the other end of the pigtail and attach it to the screws the same way as before: green goes to green, white goes silver, black goes to bronze.
    • Older houses might have different types of wires, so you may need to consult an electrician if yours don’t match up.

Finishing the Job

  1. Put everything in the wall and install wall plates. You'll only need two screws on the device, to screw directly into the box. The outlet itself should then be screwed directly onto the box with the screws included.
    • Once you put the device in, fasten the wall plate using a screw and put all the wires into the receptacle to tidy up the job. Screw the cover plate onto the wall and repair any holes you made in drywall, if necessary.
  2. Turn the power on to test your work. The circuit should remain on and the fuse should not pop if you've installed the wires correctly. Test the outlet with a lamp, or some other low voltage device.
    • If the fuse does pop, or the power doesn't work, turn the power back off and pull the connections back out to check them. It's likely a wire or two came loose in the maneuvering process, and should be reattached accordingly.
    • Be very careful that you turn the power back off, before you check, if there's some kind of problem. If the circuit's on, there should be power, which means that you've got to be very careful.
  3. Test the outlet with an outlet circuit tester. Most household circuits are 15 amps, and it's a good idea to test the circuit to make sure the new circuit won't overload it. Most electricians will do this after installation, to make sure the new circuit isn't stressing the source. To do this, you'll need to use a voltage tester, connecting between the terminal screw on the breaker, and the other on the ground. Don't touch the neutral wire.
    • For most circuits, the maximum power available should be 1800 watts for everything on this circuit, but it's usually common to reserve about 20% in case you need to plug a high-watt appliance into the outlet. Try to keep it around 1400 watts max, to leave you a good safety margin.

Tips

  • Extension cords were made for this purpose (but only for temporary use). It's cheaper, easier and less dangerous to buy a cord and run it to where you occasionally need power.
  • If you are investigating the basement or crawl space, you may find wires hanging down, but not electrical boxes. In most regions, it is acceptable to interrupt a wire so long as the connections you make end within a new electrical box. Find a wire that appears to connect to an existing outlet in the room and be sure that it has some slack (you can get about 6 inches of the wire folded onto itself). With the power off, you can cut the wire. Place both ends of the cut wire into a new electrical box, mount the box on a floor joist and tie in your new wire to the existing wires.
  • If you have an attic or basement/crawl space, you must investigate the route for running your power to it. Sometimes power is run to ceiling light boxes in the center of the room. Other times, only the wires for powering the light itself are in the box. You can check this by turning off the power to a room (or building to play it safe), taking off the light fixture and seeing if there are more than two wires entering the ceiling light electrical box. If more wires come in (and then more than likely go out a different way), you more than likely have live and constant power running through that box. You can possibly connect to those additional wires.

Warnings

  • Constant over-load current can cause wires to overheat and ignite the insulation and other building materials.
  • Household current is enough to cause electrocution (death or injury) if a person is grounded or touches two wires, thereby completing the circuit.
  • Do not put an extension cord where it would receive wear and tear from foot-traffic and doors closing on it.
  • In most locations, there are code requirements for work such as this. Doing it yourself can increase the likelihood of fire too. It is easy, due to the complexity of this, to allow too much current to be drawn through a single circuit.

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