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How to test switch or circuit breaker? Testing a switch with a multimeter

Testing a light switch with multimeter is not rocket science. But it becomes life-threatening when you don't know how to test it with safety. Before testing any switch or circuit breaker you must know about its construction. From a variety of switches, I will discuss here single pole switch, three-way switch, and how to test a light switch with a digital multimeter. If you don't know about what a multimeter is or how to use it the you can learn from here.

What is an Electrical Switch?

"A switch is used to cut-off or on the electrical current through any circuit." In other words, it is an electromechanical device that permits alternating-current (ac) electricity to flow through it as designed and opens up to break the circuit when needed.

Most Common Types of switches:

There are many types of electrical switches available in the market. Out of them, a few major ones will be discussed here:

1) Toggle switch:

A toggle switch is a type of ON-OFF switch and it has a handle attached to it. The handle can rotate right or left depending on its position. A toggle switch can be either of momentary type or maintained.


2) Rocker switch:

Rocker switch type is also just like other ON-OFF switches. But it has a metal contact connected to a rocker arm with a switch cover plate. The rocker arm can be moved up and down, side to side. It is the most used switch in homes.

3) Push-Button Switch:

A push-button switch or general-purpose switch is a type of ON-OFF switch. It is manufactured with plastic or bakelite.

4) Slide switch:

A slide switch is a type of ON-OFF switch that is closed when it is slid from its resting place. It can have external or internal contacts.

Which multimeter is best for switch testing?

You can test any switch, be it a 3-way or 4-way switch with the help of a multimeter. But you must know how to use it properly. It is not very difficult but you should practice more if you are a beginner in the field of electronics. You can also visit my list of best multimeters for home use.

A multimeter is of two types. You can either use a digital multimeter or an analog multimeter to test a switch.

A digital multimeter has a numeric display and it is better than the analog. It is of pocket size and very easy to carry. You will get more accurate results than any analog multimeter. So, all-in-all a digital multimeter is better than an analog multimeter. You can also use an ohm meter or non-contact voltage tester to check any breaker box electrical connections.

Tools needed for switch testing

You will need the following things for testing a switch:

  1. A multimeter with an audible continuity tester.
  2. A screwdriver for mounting screws, and tightening of screw terminals
  3. Some new switches
  4. Some jumper wires (just like the same wire which is already installed)
  5. Regulated Power supply

Step by step guide to test light switch multimeter

You can perform this guide to test any electrical switch using this light switch testing guide.

  • Before you start testing the light switch, first disconnect the power supply. Do not ever perform any kind of electrical work with a power supply plugged in.
  • Using a screwdriver, open up the light switch cover. If the light switch has two terminals then it is a single pole light switch and if it has three terminals then it is a 3-way light switch. It will also have two terminals as the light itself.
  • For testing a light switch, you will need to test for light continuity. If the light turns on when the light switch is turned on then the light switch is good. But if the light does not turn on when the light switch is turned on then the light switch is bad.
  • To test light continuity, connect the positive lead of the multimeter to the light switch terminal. Then connect the negative lead of the multimeter to the light fixture terminal.
  • Now set the multimeter to continuity if it beeps then it is in good condition otherwise just replace the light.
  • Now if you want to test any switch with a multimeter then you have to perform the same continuity test on a light switch.
  • Place the red test lead on one terminal of the switch and the black lead on another terminal. Set the multimeter to continuity if it shows continuity at one position and infinite resistance at off condition then it's ok. Otherwise, you have to change it with a new switch.
  • If you have replaced a faulty switch then always check the electrical continuity of the same lighting circuit.
  • There might be a chance of damaged insulation or overheated wire due to the switch malfunctioning so always perform a continuity check of the same light socket.
  • If you're curious about how to test electrical wires with multimeter then I have made a separate blog for you.

Why is it necessary to perform this test?

A switch is a very important instrument in the home. A faulty switch can lead to accidents and even loss of life. It is always better to test the switch before you repair or replace it. Otherwise, you may end up replacing a good switch with another bad one. Disconnecting the power supply is always advisable before you start repairing any switch. After switch testing, go to the fuse panel and check all fuses, if there is any blown fuse then replace it accordingly with the new one. Looking for best multimeter for automotive for more guide.

Safety Guide

Most of the faulty switches can be easily tested with a multimeter. You do not need a master's degree in electronics to test a switch with a multimeter. But there are a few things that you should follow,

how to test switch with multimeter
  • Never perform electrical work while the power supply is connected.
  • Always wear rubber-soled shoes while working on electrical equipment. Do not wear leather-soled shoes or shoes without shoelaces as they might provide you an easy path for current to pass through your body.
  • Always inform others around you when you are testing a switch with a multimeter.
  • Never fiddle with the wiring of electric equipment while they are under load.
  • Always shut off the main power supply before you start any electrical work in your house.
  • Always wear protective gear when doing electrical work at home like rubber gloves and safety goggles etc.
  • Periodic maintenance is required for the screw terminal switches. Always check the termination of connections and tighten them if they are loose.
  • Lastly, you should always be aware while using a tester probe kit. When measuring electrical things (such as AC voltage), probes touching each other can cause an explosion.

If you follow these simple steps, then there is nothing to fear about working on faulty switches. Most of the incidents happens while checking Christmas light, that's why I have made a separate guide for that.

Conclusion-The Wrap-up

Testing the switch with the help of a multimeter is very easy. You just have to follow step by step instructions that are given above. Testing light switches is something that everyone can do at home. If you like this article then please share it with your friends via social media sites like Facebook and Twitter. checking amperes with multimeter is a bit risky but I have made it easier with a step by step guide.

If you want to know which multimeter is best for electronics work you visit my blog for it. 10 Best multimeter for electronics work

Frequently Asked Questions-FAQs

Why it is necessary to use an electrical box for light switch installment?

Although it's not necessary to install light switches in an electrical box for indoor electrical work. Normally you have to use a breaker box in outdoor installations due to weather conditions. After making connections.

Is it necessary to use a ground or earth cable?

Yes, it is necessary to use a ground cable. Because it saves your equipment for short circuits and provides the shortest path to complete an electrical circuit. It will be much easier to troubleshoot all electrical properties if you use a green ground wire or bare copper wire.

Why it is compulsory to test continuity single-pole switch?

Because with continuity it is easy to trace lose connections. The other major advantage of continuity testing is that you don't need an active or energized system for troubleshooting.