Test a Light Switch with a Multimeter

The Ultimate Guide to Testing a Light Switch with a Multimeter

We all have countless light switches in our homes and work areas. We use them every single day to turn the lights on and off. But only some of us know how the light switches function and what could lead to their demise sooner or later.

If your light switch stops functioning properly, chances are there is a problem with the button or the wires. Even the most high-quality switches can become faulty after some time. While you can change the light switch to try and eliminate the problem, that will not do any good if the problem is not the light switch but the wiring or the electricity.

So, how do you test a light switch to see what is wrong with it?

I am glad you asked! In today's guide, I will give you a detailed overview of how to test a light switch with a multimeter if you suspect it is faulty. To learn more about the tool and testing process, including the switch removal, wire detachment, and evaluation process, stick around for the rest of the guide!

How to Test a Light Switch with a Multimeter? Step-by-Step Guide

First, let's define what a light switch is. This is the switch you use to turn the lights on or off. The electric current flows without interruption whenever you push the button to turn them on. Whenever you press the button to turn the lights off, the button cuts the flow's path and causes an abrupt stop.

So, light switches can go faulty with time, or there could be a problem with the wires that connect the switch to the electric current. These two issues would cause the light switch to appear faulty. If that ever happens to you, I recommend you inspect the switch with a multimeter.

A multimeter is a testing tool you can use to measure the electrical properties of a device. You can use it to test or measure electric current, voltage, and resistance, or you can use it as a continuity tester. The tool is safe and easy to use, but you must know exactly how to use it.

To learn how to test a light switch with a multimeter, read the following step-by-step guide:

Step 1 - Turn Off the Power Supply

Every electrical device in your house must be attached to the electrical grid to function correctly. That is made possible through wires that go up to the electrical box. If you want to stop the electricity from powering a specific device, detach the fuse from the fuse panel or flip the circuit breaker.

The best thing would be to go to the electrical panel in your house and turn the electricity off all devices, including light switches. Check the switch with a non-contact voltage tester to ensure no electricity is going through it. That way, you know it is safe to work with the switches, remove them, detach them from the wires, etc.

Step 2 - Check Light Switch Type

Light Switch Types

After turning off the electrical circuit from the breaker box, I recommend that you look at the particular light switch to see what type of switch it is. This will help you determine how to remove and detach it safely.

There are several common types of light switches - the single pole switch, the three-way switch, the dimmer switch, the four-way switch, etc. Look into your switch and determine which type it is depending on how it looks. If you cannot tell by looking at it, consider removing the switch cover plate to see what lies beneath.

Depending on the number of outputs below the cover plate, you should be able to tell what type of wall switch you are dealing with.

Step 3 - Remove the Light Switch

To test a light switch, remove it from the wall. While some light switches come with screws, some do not. The latter should be removed with a flat screwdriver that you use to remove the wall plate first. Then, you will expose the screws you can unscrew using the same screwdriver.

Step 4 - Detach the Wires

After removing the light switch from the wall, you will expose the wires connected to it and allow it to turn lights on and off. Depending on your switch type, you will have different wires connected to the switch.

What you need to do next is gently detach the wires from the light switch. You can do this by gently pulling the wires, which should come off easily.

When you finish removing the wires, you should have a light switch that you can take anywhere you want. That means that you are about ready to start with the actual testing!

Step 5 - Adjust the Multimeter

fluke multimeter light switch

Grab your multimeter and set it to continuity, as you will use it as a continuity tester. The icon for continuity looks like a play button next to a vertical line, with a horizontal line going through both. The icon's look can vary depending on your multimeter type.

There will also be two wires that you need to attach to the multimeter. Make sure you connect them as listed on the manual or multimeter packaging. That is essential if you want the multimeter to work correctly when doing the continuity test.

Step 6 - Attach the Multimeter to the Light Switch

Next, you need to attach the multimeter wires to the light switch. You can use the screw terminals to attach the wires. The screw terminals are located on the back of the light switch and are where the electrical wires are attached. Again, depending on the type of switch, you can have two or three terminals, side terminals, a traveler terminal, etc.

Step 7 - Test & Evaluate

Now, you can start doing the test and evaluate the results as you go along.

When you turn the multimeter on, which is attached to the electrical device, it should start emitting a sound to show that electricity is going through the device, which means the device is not faulty.

If the multimeter is set to continuity mode, turned on, and attached to an electrical device but does not make any sound, the device is probably faulty. There is something that does not allow electricity to get to it. It might be that the device has simply run its course and is no longer usable.

While most multimeters let out a sound to allow you to see if your device is faulty or not, some also feature a screen that shows the numbers "0" or "1." If you have such a multimeter, you should know that anything between "0" and "0.99" means electricity is going through the device. In contrast, a steady "1" means no electricity goes through the device.

Depending on the results, you should know where the problem lies - whether you have a faulty switch or a problem with the light fixture wires.

Extra Tips

Now that you know how to test a light switch with a multimeter, I want to tell you more about staying safe during the process. As mentioned above, I always recommend you turn off the electricity to the house and do a voltage test with a non-contact voltage tester before doing anything else.

Another thing you should do is use safety equipment throughout the testing. Safety goggles and gloves can make quite a difference when working on light switches or any other electrical device.

Finally, I want to tell you about cases when you do not need to do testing - you can replace the light switch, light fixture, or other devices immediately. If you hear it is making buzzing, clicking, popping sounds, or if it becomes too hot while working, chances are the device has already run its course.

You can go through with the testing, but 99% of the time, the results will tell you that you have a device that is not working properly. Since there is no point in trying to repair something like a bad light switch, I recommend installing a new one immediately.


You are at the end of today's guide on how to test a light switch using a multimeter. I hope you learned valuable information from this guide, and I encourage you to remember the tips and tricks shared so that you can do your multimeter tests whenever you encounter problems with your light switch.

Always take the proper safety precautions when doing the testing. Remove the switch, attach it to the multimeter, and perform the test. If you get a "0" or a beeping sound when turning the multimeter on, your switch is still functioning, and something else is causing the issue.

If you have ever performed such tests, let me know in the comments below how it all went. I cannot wait to read all about your experiences!

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