Electrical How-To bolt logoElectrical How-To

Install or Replace a Light Switch

beginner
Light switch with the cover plate removed showing screw terminals and wires
A single-pole switch with the plate off, showing its screws.
Safety first

Turn off the breaker and verify power is off before working. If you are not comfortable, hire a licensed electrician.

Step-by-step
1

Turn off the breaker and test the wires.

Non-contact voltage tester held against an outlet slot to check for power
Touch a non-contact tester to the outlet or wires. No light or beep means the power is off.
2

Remove the old switch and note which wires are connected to each terminal.

3

For a standard single-pole switch: connect one hot wire to each brass terminal.

Diagram of a single-pole switch showing line, switch leg, and ground terminals
One black wire goes on each brass screw. It does not matter which is which on a simple on/off switch.
4

If a ground is present, connect it to the green screw.

5

Fold wires into the box, secure the switch, and install the cover.

6

Turn the breaker on and test the switch.

Pro tip for you

If you see a white wire connected to the old switch, it is likely a switched-hot (not a neutral).

Tools
  • non-contact voltage tester
  • screwdriver
  • wire stripper
Materials
  • single-pole switch (15A or 20A)