How to Test a Limit Switch With a Multimeter

Limit switches are an important part of many industrial and manufacturing processes. They act as a safety mechanism, preventing equipment from being damaged by shutting down operations when they reach a certain point. To ensure your limit switch is functioning properly, you can use a multimeter to test it. This article will show you how to test a limit switch with a multimeter. Keep reading to learn more.

What Causes Limit Switches to Fail?

There are a few different reasons why a limit switch might fail. The most common cause is wear and tear. Over time, the contacts in the switch can become worn down, making it less effective at closing or opening. Another common cause of failure is dirt and debris build-up. This can prevent the switch from moving properly or block the contacts from making contact.

Additionally, limit switches can fail due to corrosion or rust. The other main cause of limit switch failure is mechanical damage. This can be caused by an impact, either from something hitting the switch or dropping the switch. Finally, limit switches can fail due to electrical issues, such as a power surge.

Why Should You Test Your Limit Switch With a Multimeter?

There are a few different reasons why you might want to test your limit switch with a multimeter. The most common reason is to troubleshoot a problem. For example, testing your limit switch with a multimeter can help you determine the problem if your limit switch is not working properly.

Additionally, you may want to test your limit switch before installing it to ensure it is working properly. Another reason to test your limit switch is to calibrate it. This can help ensure accuracy and prevent problems down the road. Finally, you may want to test your limit switch periodically as part of a preventative maintenance plan.

Step by Step How to Test a Limit Switch With a Multimeter

1. Gather Your Materials

The first step is to gather the materials you will need for the project. You will need a multimeter, a limit switch, and some jumper wires. Gather these items and have them ready to go before you begin. If you do not have a multimeter, you can purchase one from a hardware store or online. You can use regular electrical wires if you do not have jumper wires.

2. Inspect the Limit Switch

Before you begin, take a close look at the limit switch. Inspect it for any damage, such as cracks, breaks, or corrosion. Additionally, ensure the switch is clean and free of dirt or debris. If the switch is damaged, it will need to be replaced. If it is dirty, you can clean it with a soft cloth. Avoid using harsh chemicals, as these can damage the switch.

3.Set the Multimeter to Ohms 

The next step is to set your multimeter to the Ohms setting. Most multimeters do this by turning the dial to the symbol that looks like a horseshoe. First, touch the black lead to the COM or common terminal on the multimeter. Then, touch the red lead to the VΩmA, or volts, terminal. Finally, touch the leads to the limit switch terminals. The switch works properly if the multimeter beeps or the reading is close to zero.

4. Set the Multimeter to AC Volts 

If the Ohms test does not work, you can try setting the multimeter to AC volts. This will tell you if any power is running through the limit switch. To do this, first set the dial to the AC volts setting. Then, touch the black lead to one of the terminals on the switch and the red lead to the other terminal.

If power runs through the switch, the multimeter will register a voltage. The multimeter will not register a voltage if no power runs through the switch. If you get a reading, that means the limit switch is working. The limit switch may be defective if you don’t get a reading. Avoid using the limit switch if it is defective.

5.Set the Multimeter to Dc Volts

If the AC volts test does not work, you can try testing the limit switch with a DC volts setting. This will test to see if there is any current flowing through the limit switch. To do this, first set your multimeter to the DC volts setting.

Then, touch the black lead to the common terminal on the limit switch and the red lead to the normally open terminal. If the limit switch is working properly, you should see a reading of 0 volts. If the limit switch is not working properly, you will see a voltage reading on the multimeter. If this is the case, you will need to replace the limit switch.

6. Set the Multimeter to Continuity

Another way to test the limit switch is with a continuity setting. This will tell you if the switch can complete a circuit. To do this, first, ensure that the limit switch is in the closed position.

Then, set your multimeter to the continuity setting and touch the probes on the switch’s two terminals. If the multimeter beeps, this means that there is continuity and the switch is working as it should. If there is no continuity, this means that the switch is not working and will need to be replaced.

7. Connect The Limit Switch

The next step is to connect the limit switch. To do this, first, identify the terminals on the switch. There are usually two or three terminals labeled “NC” for normally closed, “NO” for normally open, and “COM” for common. The NC terminal is connected to the load when the switch is open, and the NO terminal is connected to the load when the switch is closed. The COM terminal is connected to both the NC and NO terminals.

8. Test the Limit Switch 

If you want to test the limit switch without a multimeter, you can do so with a jumper wire. To do this, find a long enough wire to reach from the power source to the limit switch.

Then, attach one end of the wire to the positive terminal on the power source and the other end to the normally open terminal on the limit switch. If the switch works, the circuit will be completed, and the power source will turn on. The power source will not turn on if the switch is not working. If the switch is defective, you will need to replace it.

9. Adjust as Needed

Once you have tested the limit switch, you may need to adjust it. This is because the limit switch can become misaligned over time. To adjust the limit switch, turn off the power to the device. Then, remove the cover from the device. Once you have access to the limit switch, you can adjust it as needed. After you have adjusted, turn the power back on and test the limit switch again.

10. Replace The Limit Switch

If the limit switch is not working, you will need to replace it. To do this, first, turn off the power to the device. Then, remove the screws that hold the limit switch in place. Next, disconnect the wires from the limit switch. Finally, install the new limit switch and reconnect the wires. Try testing the limit switch again. You may need to consult a professional if it still does not work.

Tips and Warnings on How to Test a Limit Switch With a Multimeter

Tips:

1. Read the manual that came with your multimeter before using it.
2. Set your multimeter to the ohms setting.
3. Place the probes on the limit switch terminals.
4. The reading should be infinity if the switch is open and zero if it is closed.
5. If you get a reading other than these two, the switch is damaged and needs to be replaced.

Warnings:

1. Do not touch the probes with your hands while testing, as you could get an electric shock.
2. Be careful not to damage the limit switch while testing it.
3. Always follow the manufacturer’s instructions when using a multimeter.
4. If you are unsure how to use a multimeter, ask someone familiar with it for help.

Conclusion

So there you have it! These are the steps on how to test a limit switch with a multimeter. Following these steps, you can easily test the switch to see if it works properly. If not, you can replace it with a new one. Just be sure to follow the tips and warnings listed above to stay safe while testing the limit switch. With a little bit of knowledge, you can easily test and replace a limit switch on your own. Thanks for reading!