How to Replace Old Wall Switches With New Ones
Wall switches for lights and other electrical devices can last for many decades, but eventually most will wear out and either fail to work or start to feel a little "iffy" each time you throw the toggle. Basic switches are inexpensive. Even specialty devices, such as four-way switches and dimmers, are also inexpensive, so replacing a tired, old switch is always a good investment. The easiest and most foolproof method for wiring a new switch is to use the old switch as a guide. Remove one wire at a time from the old switch and connect it to the same type of terminal on the new switch. If the new switch looks different and the connections are not obvious, consult the manufacturer's wiring diagram.
Shut off power to the switch's circuit at the home's service panel (breaker box). Remove the two (or more) screws securing the switch coverplate. Remove the coverplate.
Confirm that the power to the switch is off by touching the probes of a circuit tester to the ground screw and to each screw terminal of the switch. You may have to remove the switch mounting screws and carefully pull the switch from the box to complete the test. Be careful not to touch any wires.
Remove the mounting screws (if you haven't already done so) and pull the switch from the box, clearly exposing each circuit wire. Compare the old switch with the new one to identify each corresponding screw terminal or wire lead. Also make sure the new switch carries the same voltage and amperage (amp) ratings as the old switch.
There are three basic types of standard light switches. A single-pole switch has two screw terminals plus a ground terminal. A three-way switch features three terminals plus a ground. Commonly used in stairwells and large rooms, three-way switches control the same fixture(s) from both switches. A four-way switch includes four terminals plus a ground. It's always installed between a pair of three-way switches, providing control of the same fixture(s) from three locations.
Disconnect each wire from the old switch and attach it to the corresponding terminal or lead on the new switch. If the wire ends appear blackened or otherwise damaged, cut back the damaged portion with wire strippers/cutters, then strip off 3/4 inch of the insulation before attaching the wire to the new switch.
Tuck the wires back into the electrical box, then secure the new switch in place with the provided screws. Reinstall the coverplate. Restore power to the circuit and test the switch.
Things You Will Need
- Circuit tester
- Wire strippers
- If your house has aluminum wiring, consult a licensed electrician. Aluminum wiring requires special devices, tools and techniques to ensure secure connections.