If you aren’t sure which breaker controls the switch you want to replace, then turn off the main power switch in the breaker box to cut off all the power in your home. Leaving the power on while you work on the light switch puts you at risk for electrocution, so always turn off the power before you start working.
If the switch plate is stuck to paint on the wall, run a utility knife around the edges of the switch plate to cut through the paint.
If there’s still power running to the switch, then it’s connected to another circuit breaker than the one you turned off.
A single-pole switch is the most common type, and it will be the only switch that controls a light fixture. It will usually have “On” and “Off” printed on the switch. 3- or 4-way switches are usually used in large rooms or hallways so multiple switches control the same light fixture. These switches usually don’t have any words printed on them.
If the wires are in a slot on the back of the switch, push the end of a small screwdriver in the slot to disconnect them. Single-pole switches have 3 wires connecting to them: a black hot wire leading back to the power source, a black or red hot wire leading to the fixture, and a green or bare copper ground wire. Take a picture of how the wires are attached before you disconnect them to use as a reference when you connect the new switch.
If the exposed end of the wire looks damaged or dirty, cut it off with wire strippers. Strip the wire so there’s 1⁄2 inch (1. 3 cm) of wiring at the end. Push-in connections where the wires fit into slots on the back of the switch are less secure than mounting the wires to the screws.
You can connect either wire to each of the screws. Your switch will still work no matter which way it’s wired.
If the switch still doesn’t work, turn off the power to check that you attached the wires securely and to the right terminal screws. If you still have trouble, you may need to contact an electrician.
A 3-way switch has 4 wires: 1 black hot wire that’s connected to the power source or the fixture, 2 black or red traveler wires running between the switches, and 1 green or bare copper ground wire. A 4-way switch has 5 wires: 2 black or red hot wires connecting to the power source or fixture, 2 black or red traveler wires between the switches, and 1 green or bare ground wire.
Take a picture of the wires before you disconnect them so you can remember how to correctly reinstall them on the new switch.
If the end of the wire is damaged, snip it off with a pair of wire strippers. Secure the strippers 1⁄2 inch (1. 3 cm) from the end of the wire. Squeeze the handles tight and pull the strippers toward the end of the wire to remove the insulation.
If you’re wiring a 4-way switch, it doesn’t matter which of the marked wires connects to each of the black common screws.
Check the other switches that control the light on the circuit to determine the position of each traveler wire. If a red wire connects to the top brass screw, then connect the red wire to the top screw on the new switch.
If the switch still doesn’t work or another switch on the circuit stopped working, then you may have connected the wires incorrectly. Turn off power and double-check the connections.
If you’re converting a single-pole switch to a dimmer, then you’ll have 3 wires: 1 black hot wire leading back to the power source, 1 black or red hot wire leading to the light fixture, and 1 green or bare ground wire. If you’re converting a 3-way switch to a dimmer, you’ll see 4 wires: 1 black hot wire connecting to the power source or fixture, 2 black or red traveler wires that run between the switches, and 1 green or bare ground wire. Mark the hot wire with a piece of electrical tape so you don’t forget. Take a picture of the wiring so you can easily remember how it connected to the switch as a reference.
If your dimmer switch has screws instead of wires, loop the green or bare wire around the green screw on the switch and tighten it with a screwdriver.
If the dimmer switch has terminal screws, then loop the wires around them and tighten them with a screwdriver.
If any of the ends look damaged or dirty, cut them off with wire strippers. Remove 1⁄2 inch (1. 3 cm) of insulation from the end of the wire with the strippers so you have a newly exposed end.
If the switch doesn’t work, turn off the breaker and check the wire connections to make sure they’re secure and in the right place. If you still can’t find the issue, contact an electrician.
