It is the responsibility of the user of this information to know and understand the NEC (National Electrical Code) as it applies to them, as well as any local regulations or laws that may pertain. While many jurisdictions do adopt the standards of the NEC, some may have requirements in addition to, or exemptions from those standards. The information on this page is intended to aid in electrical wiring projects that become necessary when doing DIY home improvements and repairs. We cannot assume responsibility for personal injury or property damage as a result of using the information provided here.
New wall receptacles and switches will have two types of contacts: terminal screws on the sides and holes in the back that accept solid, 12 and 14 gauge wires only. Both of these devices are available for 15 and 20 amp circuits. Be sure to use the proper size for the circuit you are working on.
In an older dwelling the devices and wiring may be outdated and you will find receptacles that are ungrounded or even non-polarized. Always use the same type of receptacle as the existing one for replacement. For instance, never replace an ungrounded receptacle with a newer, grounded one if no ground wire is present.
There are 3 basic types of wall switches you will encounter in most situations. A single-pole switch is the most common you will find and can be identified by two screw terminals, and in some cases, a third one for ground.
The second most common type of switch you'll find is a 3-way switch. These are identified by three terminal screws and a forth one for ground. A 3 way switch is used to control lights from two locations. The last most common switch you will find is a 4-way switch. These have four terminal screws and a fifth for ground. Four-way switches are used between two 3-ways to control lights from 3 or more locations.
An old switch can be replaced with the same type or you can change a single-pole switch to a rheostat dimmer if it controls an approved light fixture. Older switches may not have a grounding terminal and there may be no ground wire present in the switch box. In these cases, the grounding terminal on the new switch can be ignored.
Shut off the electricity at the service panel for the circuit you will be working on. Test the circuit using a known working lamp or other electrical device to be sure it's off. Flip a light switch to be sure the bulb doesn't light, or use a volt meter to test the wires and confirm the circuit is off. Remove the cover plate and the top and bottom bracket screws holding the device to the outlet box. These are long screws and easier to remove with a drill-driver if you have one.
Grasp the top and bottom brackets and pull the device straight out from the outlet box so you can reach the sides and back. If you will be disposing of the old device, remove the terminal screws holding the wires, this will make it much easier to free the stiff copper. Leave the wires bent into hooks if you will be using the terminal screws to connect the new device. If you will be using the holes in the back, cut the wires right below the hook so you will have a straight piece to insert into the holes. Strip about ½inch of insulation off the conductor to make the connection.
If the existing receptacle or switch is connected through the holes in the back, push a jewelers screwdriver or similarly shaped tool into the slot next to each hole to release the spring pressure and pull the wire free.
Attach the wires to a new switch connecting the hot source to the bottom terminal and the wire running to the light to the top terminal. On a receptacle the hot source goes on the positive (+) or brass colored screws and the neutral goes to the negative (-) or silver colored screws. If there are two sets of wires on a receptacle, keep them in sets using the top terminals for one and the bottom terminals for the other set. Place the wires so they point in a clockwise direction and the insulation runs all the way up to the screw. Don't leave any bare copper between the terminal and the wire insulation. Tighten the screws to clamp the wires down.
If you are using the holes in the back, push them into the proper holes until the spring engages and locks them in place. Pull on each wire to be sure it is securely connected. Connect any bare or green ground wires to the grounding terminal on the device and any terminals integrated into the outlet box. If there are several ground wires, tie them all together with a splice and a short piece of wire to connect to the terminal. There is no hole in the receptacle or switch for the ground wire, only a screw.
Leave the device hanging free and test it to be sure the wiring is correct. Plug a lamp or a receptacle analyzer into receptacles and turn the power back on at the service panel. Go back and check for power at the receptacle and flip new switches to be sure they're working. If there's a problem with the wiring turn the power off again and correct the problem.
If the wiring is correct turn the power off and install the device in the outlet box. Carefully fold the wires to fit into the box and push the device with your palm until it sits flat and is aligned with the bracket holes. Drive the bracket screws and shift the replacement of the device left or right as necessary to square it in the box as you tighten them down. Install the cover plate, turn the circuit back on and test the device again.