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A Full Guide On How To Test a Light Switch [Problem Solved]

Light switches are used thousands of times every year. It’s normal for them to wear out or go bad over the years. If you think you’ve got a bad light switch, no need to worry. You can either call an electrician or test the switch yourself. Luckily, testing a light switch is super easy and simple. 

How to test a light switch?

First, you have to turn off the circuit breaker. To do that, locate the breaker switch and simply turn it off. Uninstall the light switch afterward. Test it for continuity. If it fails, it must be replaced. If the switch is still functional, install it back. When you’re done, turn on the breaker switch to activate the circuit breaker. 

That was just a short version of the answer. There’s still more to know. That’s why we’ve brought everything into one place to help you out.

Want to know more about the switches and how to test them? Keep reading till the end!

How to Tell If Light Switch Is Bad: 5 Signs You Should Look Out For

Switches go bad over time. We all know that. As we constantly turn them off and on, they start to wear down. Electrical connections can get altered and sometimes switch parts may get broken. 

Anyway, you have to replace the switches if you see such symptoms. Here, I’ve prepared some of the easiest signs that are super noticeable. 

Sign 1: Lights Not Turning On

If the light doesn’t turn on despite turning the switch on, that’s the clearest sign. This indicates a lack of continuity in the wiring of the switch. You should test the continuity of the switch.

Sign 2: Flickering or Finicky Lights

Let’s be honest here. We’ve all seen finicky lights at least once in our life. This happens due to a poor connection between the switch and the wire. 

Usually, the light beeps once or twice before turning on completely. This only indicates a poor connection and nothing else. It’s a good practice to replace the switch before it gets worse. 

Sign 3: The Switch Sparks

Occasionally you can see a small spark when you flick the switch. This is called load arc. 

Sparking occurs when the connections have a larger gap. It can also be a ruined wire or melted metal. But a large spark may indicate that the switch has gone bad.

Sign 4: Noisy Switch

If a switch makes clicking or popping noise, it indicates that it is not working properly. It might require a replacement.

Sign 5: Switch is Warm

Standard toggle switches are not meant to feel warm to the touch. But it’s quite common to have warm switches. 

A lot of people may ignore this but that’s actually super serious. The heat may melt your switch. It can also cause sparks or ruin the device that is connected. Always replace a warm switch.

7 Steps for Testing Light Switch

The process of testing a switch is easy. But there’s still a danger factor as you’re dealing with circuit wires. It’s super important that you make sure that the circuit breaker is turned off. Double-check it if you need to. 

But there is one condition that may keep you from testing it. If your circuit breaker is old, it’s better not to deal with it. This requires expert electricians. Besides, make sure you’re wearing a shoe and not bare-footed! 

Anyways, you will need a few things to conduct the test. These are-

  • Non-contact voltage tester, 
  • Screwdrivers, 
  • A multimeter, and 
  • Electric tapes

You can also wear gloves while doing the test. Wear the same kind of gloves used for rewiring your house. Let’s now look at the 7 steps of testing a light switch-

Step 1: Switch Off the Power

This is a vital step because of safety purposes. This can be done by switching off the appropriate circuit breaker. The circuit breaker can be found in your home’s main service panel. 

Old fashioned houses from the 70s or 80s may have a fuse system. If so, just unscrew the fuse and then pull it out from the socket. 

Step 2: Test for Power

Remove the switch cover plate and expose the switch wiring. After that, take a voltage tester and test the wires.

If there’s any voltage, turn off the circuit breaker.  

In case you don’t have a voltage tester, I’ve mentioned my personal favorites-

Product 1
Product 2

Step 3: Identify Switch Type

A factor for testing switches is that switches are of different types. This is why we must first identify the type with which we are working.

To differentiate single-pole switches from others, check if there are 2 side terminals. A 3-way switch has 3 different terminals.

The third type of switch is known as a four-way switch. Because it has four screw terminals.

Step 4: Disconnect and Remove the Switch

Loosen the screw of the terminals and pull the wires out. These will terminate the switch. 

To test the switch, place it on your work surface. You could also disinfect your light switch before removing them.

Step 5: Test the Continuity of the Switch

The continuity testing process depends on the type of switch. That’s why we’ve categorized and explained them one by one. 

Single-Pole Switch:

First, get the tester and clip one of its wires to a terminal. When you’re done, get the probe and connect to the other terminal. Turn the switch on to light up the tester. 

If it lights on, it means the switch is healthy and working nicely. The opposite means the switch has gone bad. If that happens, replace the light switch. 

Three-Way Switch:

Take the tester and connect its black wire to the common terminal. This is the same as the previous section. Attach the probe with a traveler terminal afterward. You can also use a multimeter instead to detect the voltage. 

Turn on the switch and check if it lights up or not. If it does, check the other terminal. If both of them do not light up, it’s defective. Get rid of the switch and install a new one. 

Four-Way Switch:

These types of switches have 4 terminals. It might get a little confusing but it’s not super complex. Just a little bit of attention and that’s all you need. 

First, connect the testing wire to the dark screwed terminal. You then have to attach the other wire to a light screwed terminal. Turn the switch on and off. 

You’re supposed to have continuity for one position. If you see both or none, then it can be defective. When you’re done, connect the wires to the other terminals and repeat the process. 

This time, you should notice continuity in the opposite position. If it doesn’t happen, then the switch is definitely faulty. Replace the switch if you get a different reading.  

Step 6: Reconnect/Replace The Switch 

In order to reconnect, you have to connect circuit wires to the switch. After doing so, tighten all the screw terminals and ground screws firmly.

The process is the same if you’re replacing the switch. Just make sure the amperage and voltage are the same. Put everything back to the place when you’re done. 


Question: Which continuity tester should you prefer?

Answer: Both non-contact testers and multimeters are good testers. But the multimeter makes a beep or buzz sound when it detects continuity. This makes it much easier to use.

Question: Is a switch supposed to feel warm?

Answer: Dimmer switches become warm after using it for a while. But, it’s abnormal for standard toggle switches to become warm. If your standard switches are warm, it’s time to replace them.

Question: Can a multimeter be used for every switch type?

Answer: Yes, a multimeter can be used for every switch type. You can easily check the switch using the meter. 


By now you probably have an idea of how to test a light switch. Be sure to take all the necessary safety measures. 

Also, consult with a professional if you’re facing difficulties! 

Until then, take good care of yourself and your light switches!