Single-pole switches are the most common light switches in a home. They have two screw terminals plus a ground screw. One screw terminal is for the "hot" wire that feeds the switch from the power source. The other terminal is for a second hot wire, called a switch leg, that runs only between the switch and the light fixture. The switch leg brings power to the fixture when the switch is turned on. The ground screw is for the circuit ground wire connection. Standard single-pole switches do not connect to neutral circuit wire.
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Always turn off the power to the switch circuit and test for power at the switch box before touching any wires or switch terminals.
Equipment / Tools
- Non-contact voltage tester
- Wire strippers (as needed)
- Single-pole light switch
Turn Off the Power
Turn off the power to the switch circuit by switching off the circuit's breaker in your home's service panel (breaker box). If your panel has fuses instead of breakers, unscrew the appropriate fuse and remove it from the panel.
Remove the two screws on the switch cover plate, and carefully remove the cover plate. Use a non-contact voltage tester to test all of the wires in the switch box to confirm the power is off. If the tester lights up, indicating the presence of voltage, return to the service panel and shut off the correct breaker, then re-test the wires to confirm the power is off.
Test for Power
Remove the two screws on the switch cover plate, and carefully remove the cover plate. Use a non-contact voltage tester to test all of the wires in the switch box to confirm the power is off. Also touch each of the switch's side screw terminals with the tester probe. If the tester lights up at any time, indicating the presence of voltage, return to the service panel and shut off the correct breaker, then re-test the wires to confirm the power is off.
Remove the Old Switch
Remove the two screws that hold the switch to the box. Carefully pull the switch from the box and check it once more to be sure the power is off to the circuit feeding the switch.
Disconnect the Old Switch Wiring
Note the switch wiring. There should be one wire only under each terminal. One of these will likely be black. The other may be black, red, or white. One of these is the power feed, and one is the switch leg, but the switch terminals are interchangeable, so there is no need to identify which is which.
If there is a white wire connected to the switch, this is likely the switch leg; it should be labeled as "hot" with a band of electrical tape so it is not confused with a neutral wire. If not, add a band of tape to the white wire.
If there are other white wires in the box that are not connected to the switch, these are neutral wires and can be left as is.
Loosen each screw terminal and remove the wire from the terminal. Discard the old switch.
Some "smart" switches, which can be controlled by smartphones and other wireless devices, require a neutral wire to maintain a wireless connection. Install these according to the manufacturer's directions.
Wire the New Single-Pole Switch
Inspect the end of each wire. It should have about 1/2 inch of bare wire at the end and should be formed into a hook-like loop. If the wire end is in poor condition, trim off the bare end, then strip about 3/4 inch of insulation, using wire strippers. Bend the end into a loop, using the wire strippers or needlenose pliers.
Connect the ground wire to the green ground screw on the switch, tightening the screw firmly with a screwdriver. Be sure that the open end of the loop is on the right side of the terminal screw so that when you tighten the screw clockwise, the screw makes the loop close a little tighter.
Connect one of the hot wires to one of the side switch terminals. and connect the other hot wire to the other terminal. Make sure all of the connections are very tight.
Metal switch boxes require a ground connection to the circuit wiring. An easy way to ground the box is to connect two pigtail wires to the circuit ground. Then, connect one pigtail to the switch and the other to the box's ground screw.
Complete the Job
Gently tuck the wires into the box, then mount the switch to the box with its two screws. Reinstall the switch cover plate. Restore power to the circuit by switching on the circuit breaker (or reinstalling the fuse). Test the switch for proper operation.