How to Remove and Test a Light Switch

If you suspect you have a bad light switch that needs to be replaced, there are two very different but equally important tests you will conduct during the process. The first is a matter of personal safety: making sure the current has been shut off and the wires are safe to touch before you begin work removing the switch.

The second test is a diagnostic one conducted after the switch has been removed. This test evaluates the inner wiring pathways of the switch for continuity to verify that there’s a problem that warrants replacing the switch.

Before You Begin

But first, of course, it’s important to rule out other possibilities for the light fixture’s failure. Try the simplest solutions first: Make sure the bulb is good and that it is is screwed in all the way. Also, make sure the circuit has power and hasn’t tripped its circuit breaker or blown its fuse. And it’s also possible that wire connections on the switch are loose and not making proper contact. This problem is often corrected simply by shutting off the circuit then retightening the wire connections.

If one of these issues isn’t the problem, then it’s likely that you have a bad switch, especially if the switch is old or the toggle lever feels a little loose when you snap it. Switches have a limited lifespan, and the springs and other inner components will eventually wear out.

To make sure you’re not performing an unnecessary replacement, test the switch for continuity to make sure.

Safety Considerations

Although the physical act of replacing a switch is quite easy, there is always a danger element to any project that involves handling circuit wires. It is essential that you make sure the circuit has been shut off before you handle the switch or its wire connections. This is the point of the first test you’ll conduct, but if you have any question whatsoever about how to do it or how to use the proper testing tools, then this is a repair that should be left to a professional electrician.

Home wiring systems can take many forms depending on when (and if) the wiring was last updated, and yours may not resemble the project shown here. If your wiring is very old, even simple projects like replacing a light switch are best handled by a professional.

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Electrical Testers

You have several options for conducting the two tests needed when replacing a light switch. Many homeowners will want to use the simplest, least expensive tool options: a non-contact voltage tester to check for power before touching the wire connections, and a continuity tester for checking the detached switch to evaluate if it is bad.

Another tool, more often used by professionals, is a multimeter, a versatile tool that can be used for a variety of electrical tests. In our demonstration project, we’ve used a non-contact circuit tester for the voltage test and a multimeter for testing the switch itself, but the multimeter also has settings that allow you to test for power.

  • A non-contact voltage tester is a battery-operated device that senses an electrical current without even touching the tool’s probes to the wires or screw terminals. Held close to live wires, it will light up or buzz (or both) if it senses live current.
  • A continuity tester is a simple electrical device with a metal probe, a diode light, and a wire with a clip at one end. It also operates by means of a battery. All this tool does is test for continuity—the presence of an uninterrupted electrical pathway. Attached to the screw terminals of a detached switch, the continuity tester lets you determine if the switch lever is properly opening and closing the electrical pathway.
  • A multimeter is a versatile battery-powered tester that measures a variety of electrical properties, such as voltage, amperage, and resistance. It can also be used for a simple continuity test. To set up a multimeter to test for continuity, turn the tester dial to the Continuity or Resistance/Ohms setting. Multimeters are sophisticated tools with many functions. Learning to use them correctly can require some practice.

Any battery-powered tester should be tested to make sure the battery is good and that the tool functions properly before you use it in project work.

  • To test a non-contact voltage tester, hold the tool near an outlet you know has live power and make sure it senses the current.
  • To test a continuity tester, attach the tester clip to the tester’s metal probe; the tester should light up.
  • To test a multimeter, set the dial to Continuity (or Ohms) and touch the two tester probes together: You should get a reading near 0, 0.5 or below.


Most multimeters have a convenient setting that allows the tool to make an audible beep or buzz when it senses continuity. This makes it much easier to use a multimeter as a continuity tester.

Disclaimer: Curated and re-published here. We do not claim anything as we translated and re-published using google translator. All images and Tattoo Design ideas shared only for information purpose.

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