How to Test a Circuit Breaker with a Multimeter

A faulty circuit breaker is very dangerous and it increases the risk of an overload current for appliances. An overload can cause a short circuit that will damage appliances and can pt the house on fire. That’s why testing the circuit breaker with a multimeter is very important.

Now, first of all, we will discuss

What is a Multimeter?

A multimeter is a tool for measuring electrical quantities like resistance, voltage, and current. All these meters (ohmmeter, voltmeter, and ammeter) that measures those quantities are combined to a single meter is known as multimeters. There are two types of multimeters:

1. Analog Multimeters

Analog multimeters work on the principle of moving coil meters. These meters use the deflection of an indicator needle to indicate the level of the measurement on an analog display.

2. Digital Multimeters

How to test ECU with Multimeter?
What does OL mean on a fluke multimeter?
what is RX1 on a multimeter?

How to use a multimeter?

how to use a fluke multimeter

A multimeter has three important sections

Display

Display is used to display the measurements or data.

Selection Knob

Selection knob is used to selects what you want to measure. You can measue electrical quantities on multimeter by rotating the knob and move to the symbol want to measure.

Ports

In Ports probes will be plugged in. There are four ports in fluke multimeter

Com Port : In “COM” or “–“ port black probe should be connected.
10A : This port is used while measuring large currents, greater than 200mA
µAmA :is used to measure small current
VΩ : This port is used to measure voltage and resistance and continuity.

The multimeter is a measuring instrument that works to combine several measurement functions in one unit. A multimeter can measure volts, amps, and ohms through outlets, fixtures, and breakers.

Tools Required for Circuit Breaker Testing

Two tools are required for testing of circuit breaker with a multimeter

Digital multimeter
Flathead screwdriver to uncover the circuit breaker box

The question arises why we need a digital multimeter why we can’t use an analog meter. As a Digital multimeter is easy to use and due to digital display chances of reading error are less. You can use any DMM to measure current, voltage, etc. But keep in mind you should know how to use a multimeter before testing.

How can you tell if you have a bad circuit breaker?

Circuit Breaker Warning Signs

Following are the warning signs for circuit breaker

Burning Smell in the Electrical Panel
Breaker Will Not Remain Reset.
Physical Damage.
Breakers Tripping Frequently.
Old Age

How to Test a Circuit Breaker Using a Digital Multimeter

There are two methods of testing circuit breakers with a multimeter

1. Voltage Testing

Voltage testing can be performed while the circuit breaker is live. For that, you need to be careful because chances of electric shock are there. That’s why I advise you to don’t go for it until you have an idea about multimeter and breakers. While testing if your meter shows zero reading or any reading below the standard then it’s faulty.

Steps Involved in Voltage Testing of Circuit Breaker With Multimeter

There are the following steps involved in the testing of the circuit breaker

Open your Circuit Breaker

Open the circuit breaker with a flathead screwdriver. Make sure to unscrew all the screw and hold it till the end.

Set the Multimeter to AC Voltage

From the Knob of the meter select the Ac voltage. Make sure that the selected voltage is in range, Like if you are working on 110V then the knob position should be at 120V. As discussed before, Put black lead in the common port and red lead in the voltage socket terminal.

Testing Your Circuit Breaker

There are two types of circuit breaker we will discuss them one by one.

Testing of Single-pole Circuit Breaker

To test the voltage of a single-pole circuit breaker. Put the black lead to the ground terminal of the circuit breaker and the red lead to the positive terminal of the breaker. For 110V reading should be around 120V. In case, if the breaker is showing zero or less the desired voltage then it’s damaged.

Testing of double-pole Circuit Breaker

Testing of the two-pole circuit breaker is similar to a single pole. As the only difference is no poles. To test the double pole circuit breaker, Put the black lead to the ground terminal of the circuit breaker and the red lead to the one side of the positive terminal. Then move the positive lead to the other side. For 220V reading should be around 230 or 240V.

2. Test Resistance of Circuit Breaker

Resistance test on a circuit breaker is as important as voltage test. If the resistance test failed don’t use a circuit breaker because it will lead to a short circuit.

How to Check the Resistance of a Circuit Breaker

There are the following steps involved in the resistance test.

Rotate the multimeter knob to ohm.
Put one lead in the clip or supply terminal
Likewise, put the other to the screw terminal.
There should be resistance reading when you turn on the breaker.
Similarly, no rating when you turn it off.

This test is also similar for the single pole and double pole circuit breaker.

After reading this article “How to Test a Circuit Breaker with a Multimeter ” you will be able to check the circuit breaker. We have tried to cover each aspect of the circuit breaker and will look for more and try to add those in the next update. Have you found anything helpful? Let us know in the comments section below.