Replacing Faulty Light Switches and Wall Outlets

By Gil Johnson

Tools You May Need
Parts You May Need
Switches: the Basics
Outlets: the Basics
Steps to Replace Electrical Switches or Outlets

Light switches and electrical wall outlets occasionally can become defective, working only sometimes or not at all. In addition to this making the light or appliance unreliable, it can be unsafe. Many people are afraid to tackle electrical projects, fearing that they will be shocked or injured. Any person, with or without vision, can safely and successfully replace electrical switches and outlets by (a) making sure that the electricity to the specific switch or outlet is turned off and (b) following the five steps described below.

If you do not have enough vision to identify the colors of the electrical wires and the color of the terminals, you will most likely need assistance from a sighted person to identify the color of the wires and to be sure you know which terminals are brass and which are nickel so that you can install them safely.

Gil Johnson: Master Carpenter and Home Repair Expert

Gil Johnson standing by his tools and equipment in his workshop

Gil Johnson, who was blinded at a young age from glaucoma, is a master carpenter and VisionAware's resident home repair guru. He is the author of Gil's Guide to Home Repairs, Gil's Guide to Woodworking, and Parenting or Grandparenting with Vision Loss at VisionAware.org.

Says Gil, "Working with wood, particularly hardwood, is my true love. After talking on the phone and writing letters and reports at work, I always found it revitalizing to work with my hands in the shop in the evening. This is true even now that I am retired."

Learn more about ways to make home repairs and adapt your home environment, using the principles in Gil's Guides:

Tools You May Need

  • Straight or Philips screwdrivers
  • Pliers that incorporate a wire cutter, sometimes referred to as linemen's pliers
  • Needle-nose pliers
  • Wire stripper or sharp knife for stripping insulation from the electrical wire

Parts You May Need

  • Replacement switch or outlet of the same amperage capacity and color of the one you are replacing
  • Replacement switch or outlet covers if the one you remove is marred, dirty, or cracked
  • Electrician's tape
  • A selection of wire connecters, also referred to as wire nuts, used to connect two or more electrical wires together or to cap off an unused wire

Switches: the Basics

  • Switches are, or should be, mounted in a plastic or metal junction box inside a wall.
  • Most often, light fixtures are controlled by only one switch, sometimes called a single-pole switch. It has a lever which, when moved into the "on" position, allows electricity to flow to the lights or other device; when moved into the "off" position, the lever breaks the circuit, thus stopping the flow of electricity.
  • Usually, the switch is installed so that when the lever is up, the light is on, and when the lever is down, the light is off. Sometimes two switches are installed in the same junction box with two separate switches that are side-by-side or are two switches incorporated into the same housing. These switches have two screws or terminals, usually located on one side of the switch where the incoming and outgoing black supply wire is connected.
  • A third terminal is located on the end of the switch where a "grounding" wire is connected. The grounding wire, which may be red or some other color than black or white, will be grounded to a water line or grounding rod somewhere near where the electrical wires enter the building.
  • A dimmer switch works in a similar manner. It will have a sliding lever which, when moved up or down, increases or reduces the amount of current, thus raising or lowering the illumination. Some light fixtures, such as fluorescent lights, cannot operate on a dimmer switch.
  • The dimmer switch may have three wires to connect the power and ground rather than terminal screws. These can be connected to the wires in the junction box by twisting the uninsulated end of the wire from the switch to the incoming and outgoing wire using wire nuts.
  • Light fixtures can also be controlled from more than one location with a two-way (double-pole), or three-way (triple-pole) switch. The three-way switch will have three terminals and the four-way switch will have four terminals.
  • The least complicated to install is a light switch that operates from only one location although multiple location switches are not much more difficult to replace.
  • Replacing switches that operate lights from two or three locations is similar to the following steps except that there are more wires to connect. When removing a two-way or three-way switch, pay attention to which color wire is connected to which terminal on the switch and try to install the new switch following that pattern.

Outlets: the Basics

  • Electrical wall outlets also should be mounted in a plastic or metal junction box inside the wall. Sometimes outlets are connected to a switch in another location. This is usually done so that lamps can be turned on near an entrance to the room.
  • Electrical outlets that power appliances with 120 volts of electricity have two screws or terminals on each side, one set being brass-colored and the other set a shiny nickel-colored. The incoming black supply wire is connected to either one of the brass terminals and the outgoing white wire should be connected to one of the nickel-colored terminals.
  • If another outlet is connected through the outlet, an outgoing black wire may be connected to the second brass terminal and the white outgoing wire should be connected to the other nickel colored terminal. You may not be able to tell which wires feed the outlet and which go on to another outlet, but it really doesn't matter so long as the black and white wires are connected as described above.
  • Tip:It is helpful to put a small piece of electrician's tape on the black wire to tactually identify it. You can also use the orientation of the light switch or the outlet to help remember where the brass terminals are located.
  • Almost all outlets have two places where an appliance can be plugged in. In older installations, the outlet will have two slots into which the plug can be inserted. Newer outlets have a third opening where the third prong of a plug can go in. As with the light switch, there is a grounding terminal located on the end of the outlet which connects the third prong of the plug to the grounding circuit.
  • Outlets that are installed in a bathroom, above kitchen counter tops, or outside should be equipped with a ground fault interrupter circuit (GFI). The outlet has a circuit breaker incorporated into the outlet which trips if too much current is drawn or if a short occurs because of moisture. The GFI outlets connect in the same way as described above.
  • Appliances such as kitchen stoves and clothes dryers, which operate on 220 volts of electricity, have only one place to plug in the appliance instead of two like the 110 outlets. It is usually controlled by one circuit breaker that is distinguishable from the 110 circuit breakers because it is much larger and is located in a separate circuit breaker box. A 220 outlet is replaced in much the same way as a 110 outlet but is connected to three wires of a much heavier gauge inside the junction box.

Steps to Replace Electrical Switches or Outlets

Step One: Turn off the circuit breaker

  • You must first turn off the circuit breaker or remove the fuse governing the circuit to which the switch or outlet is connected. Older homes and apartments often have one or more fuse boxes with anywhere from two to eight fuses.
  • The fuse box is metal and may be located in a stairwell, closet, basement, or garage. The surface of the box may be flush with the surrounding wall or it may stick out a couple of inches. The box will have a metal door which must be opened to expose the fuses.
  • Fuses lay flat on the outward-facing surface. They are round and screw into a socket in the box very much like the socket for a light bulb. The fuse can be unscrewed by turning it counter-clockwise.
  • Circuit breakers are standard for all newly-constructed and remodeled homes. They serve the same function as older model fuse boxes, and are generally found in the same areas of the home. Circuit breakers look like small light switches and are generally organized in rows of two to eight or more that can run horizontally or vertically. To trip a breaker, the switch-shaped button is moved down, up, or side-to-side depending on the position in which it was installed.
  • When electrical circuits were installed, the installer should have provided a list that tells which outlets and lights are on each circuit. If no additional outlets or lights have been added since installation, you can quickly tell from this list which fuse or breaker governs the switch or outlet you need to replace. If the circuit list is not available or has not been kept up-to-date, it may be difficult to determine which fuse or breaker governs that particular switch or outlet.
  • You may wonder how you can tell which fuse or breaker governs a non-working light or outlet. If you are not certain you have found the correct fuse or breaker, you can turn the power off to the entire house or get a circuit tester to determine if there is electrical current in the wire by the switch or outlet.
  • Tip: If there are two switches mounted side by side in the junction box or two switches on one unit, be sure that the circuit governing both switches are turned off.

Step Two: Remove the switch or outlet plate cover

  • Once you are certain that the electricity is turned off to that circuit, remove the plate that covers the switch. There are usually two screws holding the plate in place. Wall outlet covers are anchored with one screw in the middle of the cover between the two electrical outlet.
  • Tip: If the plate has been painted over, the slot in the screw may be covered with paint. You can expose the screw slot by scraping away the paint with a screwdriver or point of a knife. If the wall and outlet cover have been painted or covered with wall paper you might carefully cut the wall paper with a knife just at the edge of the cover before removing it. This will help avoid damaging the finish on the surrounding wall. You can get a slightly larger plate cover than the one you removed which will cover the edges.

Step Three: Remove the switch or outlet

  • The switch or outlet is anchored in place with a screw at either end. These screws may also have paint in the screw slot which should be removed as described above.
  • Once these screws have been removed, you should be able to grasp the switch or outlet and pull it out of the junction box.

Step Four: Disconnect the old switch or outlet and connect the new one

  • In older installations, the switch may only be connected with two wires, the incoming and outgoing black supply wire, and there may not be much slack wire in the junction box. The white wire may be connected somewhere in the circuitry or it may be found at the back of the junction box. In older installations, a grounding wire may not have been installed.
  • To remove the defective switch, disconnect the two wires from the terminals by loosening the screws in a counter-clockwise direction. The screws can be removed entirely, but the last turn or two may require a bit of force because of the way in which the threads holding the terminal are made.
  • If you do not remove the screw, you should find that the wire is curled around the screw terminals in the same direction that the screw is tightened. By using the point of a knife you can straighten the wire enough to lift it off the screw.
  • If the wire is not connected to the screw terminals, it may be connected by being inserted into a spring-loaded slot on the back side of the switch or outlet. You may be able to release the spring and withdraw the wire by using a straight screw driver or the point of a knife in an access slot that is provided. If the spring doesn't release, you may have to cut the wire with a wire cutter. If you do, make the cut as near to the switch as possible thereby leaving as much slack wire in the junction box as possible.
  • Tip: If for some reason you cannot finish connecting the switch or outlet and have to complete it at another time, you can place wire nuts over the ends of the unconnected wires and turn the electricity back on until you have the time to finish the job. If the wire nuts are fitted snugly to the end of the wires, there should be no danger so long as no one moves the wires around or loosens the wire nuts.
  • Connect the new switch or outlet by connecting the wires to the screw terminals as described above. Be sure to make a loop using the needle-nose pliers and placing this behind the head of the terminal screw head. Be sure that the loop curls in the direction that the screw tightens.
  • You can close the loop before tightening the screw by using the needle-nose pliers so that the wire doesn't slip out from under the screw head as you tighten it. Tighten the screw by turning it in a clockwise direction until it is snugly tight. Be careful not to over-tighten the screw.
  • If you had to cut the wire to remove the switch, remove ½ to ¾ inches of insulation from the wire with the wire stripper or by carefully cutting it away with the knife. Be careful not to nick or scratch the wire if you strip it, thereby weakening the wire and possibly causing it to break when you bend it to go under the terminal. If you prefer, you can insert the stripped end of the wire into the spring-loaded slot.
  • If there is no grounding wire, there is not much you can do about grounding it unless you want to install a grounding circuit which can be difficult because of accessing the outlet junction box inside the wall. The switch or outlet will function without the grounding wire but electrical code usually requires that the switch or outlet is connected to a grounding wire.
  • Tip: It is a good idea to place a strip of electrical tape over the terminals thereby helping to assure that the terminals will not make contact with the junction box.

Step Five: Finish the job

  • Anchor the switch or outlet back into the junction box with the new screws that are supplied.
  • Tip: If the junction box is recessed a bit below the surface of the wall, you can put plastic spacers which look like thick washers on the mounting screws between the outlet or switch and the box. This will allow the switch or outlet to be mounted flush with the wall which will make it easier to use.
  • Tip: Bend the connecting wires before pushing the switch or outlet into the junction box so that they fold in behind the switch or outlet and then insert the mounting screws to secure it in place. This makes a much neater job and helps eliminate excessive force on the connection at the terminal screws.
  • Tip: Remember to orient the lever on the light switch so that when it is in the down position, the light will be off. If the light is operated from two or three locations, the lever may be up or down depending on which switch was last activated.
  • Lastly, replace the cover. Turn the electricity back on and if it was the switch or outlet that was faulty, your light and outlet should work properly.

If you have any home repair questions, comments, or advice, feel free to post them on our Home Repairs Message Board.

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