A Bad Light Switch 

Light switches are easy to take for granted. They get used thousands of times over the years, until one day they start to fail and need to be replaced. Some signs of a bad light switch are clear. For instance, if there is an audible snap, crackle, or pop when you flip the switch, it’s pretty obvious the switch is defective and it’s time to replace it with a new one.

Are you concerned about one or more of your light switches? Keep reading to learn how to diagnose light switch issues and what to do next.

Why Do Light Switches Go Bad?

Just like any other type of simple machine, light switches have several moving parts. Over time, they wear down. Connections can become loose and plastic parts may break. Someday, each of your light switches will need to be replaced.

Four Signs It’s Time to Replace a Light Switch

When you’ve put a fresh light bulb in the fixture but the switch still doesn’t turn it on, that’s a clear sign that the light switch has died. Here are four more signs that a light switch has gone past its prime.

1. Finicky light fixture
   We’ve all had that one light switch that just doesn’t work right. Sometimes it turns on, sometimes it doesn’t. Occasionally it flickers for a second before turning on. And putting in a new light bulb doesn’t fix the flicker. If this is happening, the proper connections are not being made within the light switch and it’s time for a new switch.
2. The switch sparks
   On occasion, you may see a small spark when you flip the light switch off. This is called a load arc, which happens when the connections within the light switch are pulled away from one another. If, however, there is a large spark that makes an audible “snap,” the light switch has gone bad. If this happens and you see smoke or scorch marks, it is definitely time to get a new light switch.
3. Noisy switch
   When working properly, light switches don’t make any noise. So, if you start to hear any clicking, buzzing, or popping coming from the switch, something within the switch is not working properly. It’s time to replace that switch.
4. Switch is warm to the touch
   When turning a dimmer switch off, you may notice that it feels a little warm to the touch after having been on for a while. This is normal. However, it is not normal for a standard toggle light switch to warm up. These light switches should always feel cool. If a switch feels warm, it’s time for a new one.

How to Use a Multimeter to Test a Light Switch

A multimeter is a handheld testing device used to measure electrical voltage. Electricians and contractors use them to troubleshoot problems on motors, appliances, circuits, power supplies, wiring systems, and more. You can use a multimeter to verify whether a light switch is functioning normally.

To test a light switch with a multimeter:

1. Turn off the circuit breaker that delivers power to the light switch being tested.
2. Uninstall the light switch.
3. Turn on the multimeter and put it on the Continuity or Ohms setting (depending on the model you have).
4. Determine whether you have a single-pole switch or a three-way switch. Single-pole switches have two side terminal screws and may have a ground screw near one of the ends. A three-way switch will have a dark-colored screw (the “common” terminal) and two normal side terminals (the “travelers”).
   1. To test a single pole light switch, touch one multimeter lead to each of the side terminals. When you flip the switch on, the multimeter should show a reading of 1.
   2. To test a three-way switch, hold one multimeter lead to the common screw, and touch the other lead to one of the travelers. When you flip the switch on, the multimeter should show a reading of 1. Then touch the second lead to the other traveler to test it as well.

If your switch fails this test, it must be replaced.

5. Once you have a functional light switch, carefully install it while the power is still off. Don’t forget to turn the circuit breaker back on!