How to Tell if a Circuit Breaker Is Bad

Co-authored by Ricardo Mitchell and Hunter Rising

Last Updated: August 26, 2024 Fact Checked

If you have a circuit that keeps tripping whenever you use electronics, it may be time to check if your breakers need to be replaced. Though they have a life expectancy of 30 to 40 years, breakers will eventually die and trip your circuits. ^{[1]
X
Trustworthy Source
US Occupational Safety and Health Administration
U.S. government agency responsible for setting and enforcing workplace safety standards
Go to source} By opening your panel and using a digital multimeter to check the voltage levels, you can easily see if your breakers are the problem. Just be careful when you work with live electricity!

Part 1

Part 1 of 2:

Testing the Breaker with a Multimeter

Download Article

1
Unplug or turn off all devices connected to the breaker. Getting all of the electronics off of the circuit will prevent it from surging. If you have labels on your breaker box for what each switch controls, take the time to check what needs to be unplugged. ^{[2]
X
Research source}
- If you're not sure what each breaker controls, unplug the electronics in the area where the breaker tripped before working on it.
2
Unscrew the panel from the breaker box and set it aside. Use either a flathead or Phillips-head screwdriver depending on what screws are on the panel. There will at least be 2 screws, but there may be more. Set the screws aside in a safe place so you know where they are when you need to put the panel back on. ^{[3]
X
Research source}
- As you remove the last screw, hold the panel up with your non-dominant hand and slowly remove the panel cover.
Advertisement
3
Turn on your digital multimeter. A multimeter is a machine that tests the voltage or current through electric components. Plug the black wire into the port labeled “COM” or “Common,” and plug the red wire into the port labeled with the letter V and the horseshoe symbol (Ω). This will ensure you're measuring the voltage of the breaker. ^{[4]
X
Research source}
- Multimeters can be purchased at your local hardware store or online.
- Check the casing on the wires to make sure they have no cracks or damage. Electricity will travel through the cracks and possibly cause electrocution. If you see any damage, use a different multimeter.
Hold the probe, the exposed metal end of the wire, so you aren't touching the exposed metal. Touch the end of the probe to the screw on the left or right side of the breaker. ^{[5]
X
Research source}
5
Put the black probe against the neutral bar. Look for where the white wires leading from your breakers attach. Place the end of the black probe anywhere on the neutral bar to complete the circuit on your multimeter. ^{[6]
X
Research source}
- Do not touch the neutral bar with bare skin since it could cause electrocution.
- If you have a double pole breaker, place the end of the black probe onto the second terminal screw of your breaker to get the correct reading. ^{[7]
  X
  Research source}
6
Compare the reading on the meter to the breaker requirements. If you have a single pole breaker, check to see if the reading is around 120 V. It may be slightly above or below, but this is fine. If the breaker reads 0, it needs to be replaced. If you have a double pole breaker, make sure the reading is between 220-250 V. A faulty double pole breaker will read at 120 V, meaning it's only operating at half power. ^{[8]
X
Research source}
- The voltage of your circuit breaker depends on the size of the wire that comes into the circuit. For instance, if you have a number 10 wire, that's equivalent to 30 amps. ^{[9]
  X
  Expert Source
  
  Ricardo Mitchell
  Electrician & Construction Professional, CN Coterie
  
  Expert Interview. 6 May 2020.}

Part 2

Part 2 of 2:

Replacing a Defective Breaker

Download Article

Look in the electrical section at your local hardware store for breakers that are the same size as the ones you're replacing. Single and double pole breakers typically range from around $5 to $10 USD. ^{[10]
X
Research source}
2
Turn off the individual breaker you need to replace. Push the switch into the off position before you start working on it. This prevents the current from traveling through the wires attached to that specific breaker. ^{[11]
X
Research source}
- If your breaker has a main circuit switch on the top or bottom, turn it off to completely shut off the electricity. If you only do this for a few minutes while replacing the breaker, foods in the fridge and freezer will keep.
3
Loosen the terminal screw and pull the wires out. Use the appropriate screwdriver for the type of screw holding your wires down. Turn the screw until the wires start to feel loose. Use a pair of needle-nose pliers to pull the exposed wires out from the terminal, making sure they don't touch any other wires or breakers. ^{[12]
X
Research source}
- Use tools with a rubber insulated handle to lower the risk of electrocution or shock.
4
Grab the front part of the breaker and pull out the old breaker. Place 2 or 3 of your fingers on the side of the breaker opposite of the terminals and place your thumb near the terminals. Pull up on the side with your fingers to pop the clips out of place and remove the breaker. ^{[13]
X
Research source}
- Do not touch the metal bars in the back of your circuit box if you did not shut off the main power. They are live and could cause electrocution.
5
Slide the clips of the new breaker in place and push it in. Put the side with the terminals into place first so the clips latch onto the bar. Push the opposite side down to lock the breaker into place. ^{[14]
X
Research source}
- Make sure your new breaker is in the off position before placing them in the box.
Hold the insulated part of the wire with the end of your pliers. Put the exposed end into the new terminal and use your other hand to screw it on. Make sure the screw is snug but not overly tight, or else you could strip it. ^{[15]
X
Research source}
Flip the breaker switch to the on position and screw the panel back on to hide the wires again. Close the breaker box to wrap up. ^{[16]
X
Research source}

Expert Q&A

Search

Add New Question

Question

How do I figure out what the voltage of my circuit breaker is supposed to be?

Ricardo Mitchell
Electrician & Construction Professional, CN Coterie
Ricardo Mitchell is the CEO of CN Coterie, a fully licensed and insured Lead EPA (Environmental Protection Agency) Certified construction company located in Manhattan, New York. CN Coterie specializes in full home renovation, electrical, plumbing, carpentry, cabinetry, furniture restoration, OATH/ECB (Office of Administrative Trials and Hearings/Environmental Control Board) violations removal, and DOB (Department of Buildings) violations removal. Ricardo has over 10 years of electrical and construction experience and his partners have over 30 years of relevant experience.

Ricardo Mitchell

Electrician & Construction Professional, CN Coterie

Expert Answer

That depends on the size of the wire that comes into the circuit. If you have a number 10 wire, for instance, that's equivalent to 30 amps.

Thanks! We're glad this was helpful.
Thank you for your feedback.
If wikiHow has helped you, please consider a small contribution to support us in helping more readers like you. We’re committed to providing the world with free how-to resources, and even $1 helps us in our mission. Support wikiHow
Yes No

Not Helpful 19 Helpful 6

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Video

Tips

If you don't feel comfortable working inside your breaker box, hire an electrician to take a look and replace any breakers if necessary.

Thanks
Helpful 0 Not Helpful 0

Submit a Tip

All tip submissions are carefully reviewed before being published

Name

Please provide your name and last initial

Submit

Thanks for submitting a tip for review!

Warnings

If your breakers still do not work, you may have an issue with your wiring. Call a professional electrician to diagnose the problem.

Thanks
Helpful 10 Not Helpful 2
Be careful while working inside your breaker box since they are live and could cause electrocution.

Thanks
Helpful 4 Not Helpful 2
Make sure you always replace a breaker with one that has the same voltage.

Thanks
Helpful 5 Not Helpful 8
Never use a multimeter if the lining on the probes is cracked or damaged. This could cause electrocution.

Thanks
Helpful 2 Not Helpful 4

Things You'll Need

Testing the Breaker with a Multimeter

Screwdriver
Digital multimeter

Replacing a Defective Breaker

New breaker with the same voltage
Screwdriver
Needle-nose pliers

[1]

Trustworthy Source

Go to source

[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

Ricardo Mitchell
Electrician & Construction Professional, CN Coterie

[10]

[11]

[12]

[13]

[14]

[15]

[16]

Log in

How to Tell if a Circuit Breaker Is Bad

Steps

Testing the Breaker with a Multimeter

Replacing a Defective Breaker

Expert Q&A

Video

Tips

Warnings

Things You'll Need

Testing the Breaker with a Multimeter

Replacing a Defective Breaker

You Might Also Like

References

About This Article

Reader Success Stories

Did this article help you?

Quizzes

You Might Also Like

Featured Articles

Trending Articles

Featured Articles

Featured Articles

Watch Articles

Trending Articles

Quizzes

Explore Categories