How To Tell If A Circuit Breaker Is Bad – 3 Different Ways

The symptoms of a bad circuit breaker can easily be confused with other issues.  Constant or periodic tripping is the most notable trait of a faulty breaker, but that can also happen for other reasons.  We’re going to show you exactly how to tell if a circuit breaker is bad and needs replacing.

If you want to know about the nature of breakers and how they are supposed to operate, skip down to the What A Circuit Breaker Is And Why We Have Them section.

Now let’s dig in…

How To Tell If A circuit breaker Is Bad

Before starting the troubleshooting process, it’s good to ask yourself a few key questions so that you are effective and efficient in solving the issue. You don’t want to end up chasing your own tail!

Important Troubleshooting Questions To ask Yourself

These questions will help narrow down the possible offender:

  • When does the breaker trip?  Are there certain times of the day, week, or year that the breaker tends to trip? This is always the first question I ask a customer. The key is to establish behavior patterns, which is very helpful to know when playing electrical detective.
    • For example, if a breaker only trips in the winter, or after a rainfall, it could be caused by water intrusion into an outside light or outlet. If it only trips at night, it could be a certain light (perhaps exterior) that is the culprit.
  • Will the breaker reset?  Once the breaker has tripped, can you reset it by flipping the handle all the way off, and then back on? If it won’t hold, you have a dead short or a bad breaker.
  • How long will the breaker stay reset? If the breaker will reset, how long before it trips again? Is it a few seconds? An hour? Or is it very inconsistent? If there’s a delay of a second or two before it trips, it is likely a water intrusion issue.

For much more detailed information on identifying why a breaker is tripping, see this article: Why Does My Circuit Breaker Keep Tripping?

how to tell if a circuit breaker is bad panel

Electrical Terms

Now, it’s critical to define a few terms so that we all understand each other.  Like any profession, we electricians use terminology that is not always obvious to someone else.

So I want to be sure that you know exactly what I mean – especially if you’re just starting to learn about electrical.  Here are a few terms that are pertinent to this article:

  • Load:  Any device, appliance, or equipment that uses electricity to operate (toaster, light, fan, etc.)
  • Outlet/Plug/Receptacle:  Receptacle outlet used for plugging a load into.  Though these three words have specific unique definitions in the electrical code, the common usage is as though they are synonyms.  Therefore, I will use them interchangeably unless otherwise noted.
  • Breaker Panel:  The enclosure that contains the breakers which feed and protect the circuits in your house.  Also called a panel, breaker box, fuse box, and fuse panel (even though there are no fuses in a beaker panel; it’s a legacy term). 
  • AFCI:  Arc-fault circuit interrupter.  This can refer to a breaker or outlet.
  • GFCI:  Ground-fault circuit interrupter.  Breaker or outlet.
  • DF:  Dual Function (AFCI/GFCI combo device).  Breaker or outlet.

With those terms defined, now we can get into the troubleshooting.

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There are three ways to test a breaker: with a multimeter, without a multimeter, and by swapping. I’ll walk you through each approach, starting with the easiest (least technical) first.

Testing for a bad breaker without a multimeter

I’m going to take you through a step-by-step process to test your breaker. And you will not need a multimeter to do this. For multimeter testing, skip to that section below.

This approach isn’t necessarily going to give you 100% certainty, but I recommend it as the first step to any troubleshooting task. It will weed out many of the potential culprits and get you pointed in the right direction fairly quickly.

unplugging appliances

This is a simple process of elimination:

  1. Disable all loads on the circuit.
  2. Turn off all lights, fans, etc. Unplug all appliances and devices on the circuit. Don’t forget about outside, attic, and crawlspace loads.
  3. Reset the breaker. If it won’t reset, go to the next section (Swapping).
  4. If it resets, turn on ALL LOADS one-by-one, waiting a minute or so in-between.
  5. Turn on all lights, and plug in all normal loads (and turn them on), one at a time.  Leave them on throughout the test.
  6. Look for an offending device or appliance on the circuit
  7. Do not ignore power strips, surge protectors, phone chargers, etc.
  8. If the breaker trips when you plug in a certain load, you’ve likely found the culprit – either the appliance or the outlet. Unplug the device and turn the breaker back on to repeat the test. Don’t assume the first trip wasn’t a coincidence.
  9. If it trips again, leave the original circuit off and plug the device into a live circuit, preferably one of the same amperage rating.
  10. If the breaker trips, the device is to blame. You’ve found your culprit.
  11. If the device works fine, it is probably a circuit breaker issue. To be certain, move on to the Testing For A Bad Breaker With A Multimeter section below.

If you have all the loads operating on the circuit, and the breaker doesn’t trip, then it’s probably not a breaker issue. Most likely, there is a device or appliance that is intermittently acting up.

To narrow it down, see this article on why a breaker keeps tripping randomly.

Testing for a bad Breaker by Swapping

Swapping breakers is the fastest way to quickly narrow down the possibilities. However, it means doing some work inside the electrical panel. So, as long as you’re confident in your abilities to do so safely, by all means, read on.

First, we’re going to isolate the breaker from the circuit. But the way you do this will depend on your particular situation. Here are the three options:

If the breaker won’t reset:

  1. Turn off the MAIN breaker to deenergize the panel.
  2. Try to reset the tripped circuit breaker. If it still won’t reset, it’s bad. If it resets, move on to the next step.
  3. Remove the breaker panel cover.
  4. Loosen the screw terminal where the wire is attached to the breaker.
  5. Remove the wire and bend it out of the way, making sure it doesn’t touch anything.
  6. Turn the MAIN back on and try to reset the tripped breaker.
  7. If it still won’t reset, the breaker is likely bad. But to be sure, proceed to Testing For A Bad Breaker With A Multimeter below.
  8. If it resets, it could still be a weak breaker, but is more likely a circuit or load issue. Proceed to the next step to find out which.

If the breaker trips intermittently:

  1. Turn off MAIN breaker to deenergize panel.
  2. Remove panel cover.
  3. With a bit of masking tape, label the tripped breaker ‘B’ for BAD.
  4. Locate another breaker that matches the tripped breaker and label it ‘T’ for TEST.
  5. Swap the two breakers in the panel.
  6. Turn the MAIN on and flip on the two swapped circuit breakers.
  7. If ‘T’ holds, and ‘B’ trips, then ‘B’ is likely faulty.
  8. If ‘T’ trips, and ‘B’ holds, then it is a circuit or load issue.
  9. If both breakers trip…
    • ‘B’ could be worn out and can no longer handle normal loads
    • ‘T’ is probably fine and there is still a load or circuit issue.
  10. If both breakers hold…
    • ‘B’ might be weak and the original circuit is nearly maxed out. ‘T’ is healthy and can handle it. ‘B’ can handle the smaller load of the other circuit… for now. Replace ‘B’ with a new beaker.
    • It’s possible that the circuit is maxed-out just enough to trip ‘B’ but not ‘T’ due to milliamp differences in tolerance. This is highly unlikely.

If it is an AFCI, GFCI, or DF breaker:

To test an AFCI, GFCI, or DF breaker, follow steps from the previous section, swapping like-for-like breakers. However, there are a few extra things to check when troubleshooting these breaker types.

For instance, one way to see if the problem is a short-circuit or overload (as opposed to a neutral-to-ground fault) is to swap out the tripping breaker (‘B’) with a regular breaker (‘T’) of the same amperage.

If the regular breaker trips, it’s a short or overload situation. This rules out ground-faults, arc-faults, and nuisance tripping (which is not uncommon with AFCI and DF breakers).

If ‘T’ holds, five things are possible:

  • An arc-fault in the circuit
  • A ground-fault in the circuit (perhaps water intrusion)
  • An appliance issue (check cords for damage)
  • An over-sensitive breaker
  • The neutral is grounded out

Note:  If the breaker was only tripping every now and then, you may have to wait long periods of time in-between some of the above steps. Since most circuits serve a variety of loads, the total load on the breaker will tend to fluctuate often over the course of a day, week, and month.

See the following articles for explanations of arc and ground fault breakers:

Testing for a bad Breaker with a multimeter

There are three ways you can test for a bad circuit breaker using a multimeter: voltage, amperage, and continuity. Knowing each way is helpful for those who may not own a multimeter, but rather only possess a voltmeter, ammeter, or ohmmeter.

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A voltage or continuity test will verify the mechanical open/close function of the breaker. An amperage test will determine whether the breaker is weak and perhaps tripping prematurely.

Let’s take a look at each approach. First, remove the panel cover.

Testing Voltage:

  1. With the breaker on, test the voltage between the breaker terminal and the ground or neutral bar. You should read approximately 120 volts. If it’s a 2-pole breaker, you should read 120 volts between each breaker terminal and the ground or neutral bar.
  2. If your voltage readings are more than 10% above or below 120 volts, check other breakers and the MAIN breaker. You might have a utility voltage issue.
  3. If your breaker won’t reset, and so you can’t take a voltage measurement, refer to the Test A Circuit Breaker By Swapping section above. Remove the wire, turn the breaker on, and test the terminal voltage to ground.
  4. Flip the breaker on and off while measuring voltage to make sure the beaker is working properly.

Testing Amperage:

If the breaker will reset and hold, do a load test by measuring amps.

  1. Identify the single wire (usually black) that is attached to the breaker terminal.
  2. Set your multimeter to AMPS and clamp it around the single wire, positioning it in such a way that you can read the display.
  3. Turn the breaker on.
  4. Make sure all loads on the circuit are on (lights, heaters, fans, appliances, etc.).
  5. Plug in and run all devices that normally operate on the circuit.  Sometimes this isn’t completely practical, but do your best.
  6. With everything running simultaneously, read the display on the meter.
  7. You should not have a reading above the breaker rating (typically 15 or 20 amps).
  8. If your reading is at or higher than the breaker rating, your circuit is overloaded. Don’t panic, as there might be simple solutions available.
  9. If your reading shows at least several amps below the breaker rating, you’re in good shape.
  10. If your breaker trips before it hits its amp rating, it may be weak. Try plugging in different loads (toaster, portable heater, etc.) to the circuit to confirm.

Testing Continuity:

If you don’t have a multimeter handy, but do have an ohmmeter, there is another way to test a breaker. It’s not quite as convenient, but it’ll get the job done in a pinch.

continuity test when breaker is off
Breaker OFF = OL (Open Loop) reading
  1. Turn off the MAIN breaker so that the panel is deenergized.
  2. For best results, loosen the screw attaching the wire to the breaker and remove the wire. But this step is not necessary.
  3. Remove the breaker from the busbar. Most breakers rock outward from the center of the panel, pivoting on the foot behind the terminal screw. Others can be slightly different.
  4. Once the breaker is out, measure the continuity between the jaws (that attach to the busbar) and the screw terminal.
  5. Set your multimeter or ohmmeter to CONTINUITY or OHMS. If you have multiple ohm settings, the lowest is best.
  6. With the breaker in the OFF position, you should get either no reading at all, infinite, open, or OL (open loop).  The precise reading will depend on your meter.
  7. If you get any ohm reading when the breaker is off, that means it is allowing voltage through and is therefore faulty. Replace it.
  8. Now, with the breaker in the ON position, you should read zero ohms, or nearly zero. You should also hear a continuous beep if your meter is equipped with audible notification.
  9. If you don’t get an ohm reading of zero (or nearly zero because some meters are imprecise), that means the internal breaker contacts are not fully closed and are inhibiting current flow. Replace it.
continuity test when breaker is on
Breaker ON = Zero resistance reading

Replacing a Bad Breaker

Now let’s go over the process of changing out a breaker. It’s a fairly simple process and poses minimal danger as long as all precautions are followed closely.

Here is a quick run-down of the steps.

  1. Turn off the MAIN breaker and remove the panel cover.
  2. Loosen the terminal screw on the breaker and remove the wire.
  3. Remove the breaker by rocking it out from the center (in most panels), pivoting on the foot, just behind the terminal screw.
  4. Once pivoted, slide the foot out of the holding bracket.
  5. With a new breaker that matches exactly, reverse the procedure. Be sure that the new breaker is firmly seated on the bus and the screw terminal is tight on the wire.

What a Circuit Breaker is and Why We Have Them

Here is a rundown of what a breaker is and why we need them in a circuit.

How A Breaker Works

A circuit breaker acts as a sort of gateway between the electrical power at your breaker panel and the circuit that brings that power to your lights and outlets. Think of it as a simple switch that turns on and off the power to the circuit.

However, unlike a normal switch, it also ‘senses’ current flow and will automatically shut off (trip) when the current exceeds its amperage rating. It then must be reset manually.

The reason for this automatic tripping feature, is to protect the wire.  If too much amperage (volume of electricity) flows through a wire, it will overheat and melt, thereby causing a fire.

There are two ways a breaker protects the wire:

  • Overcurrent protection:  In the case that there is too big of a load on the circuit, the breaker will trip when the amperage draw on the circuit is above its rating.
  • Short-circuit protection:  In the case of either a line-to-line or line-to-ground fault, the breaker will trip instantly.

Both of these functions are extremely crucial to prevent fires from occurring.

How Does A Circuit Breaker Stop Working?

There are a few different ways a breaker might fail:

breaker internal parts
Image courtesy of Realpars.com
  • Worn-out internal parts:  Over time, a breaker’s internal parts can wear down and begin to weaken and malfunction. Usually, this is only if the breaker has seen high amounts of tripping and resetting.
  • Melted internal connection:  If a breaker has a severe trauma event (e.g. a big short-circuit or voltage surge) it is possible, though unusual, for the internal mechanism to get welded together. The breaker will not trip. In some cases, it will not even shut off manually.
  • Worn-out switch mechanism:  If a breaker is used as a switch daily, this can eventually wear out the switching mechanism and cause premature breaker failure.
  • Manufacturing defect:  Sometimes it’s just a simple case of poor quality. This is rare, but every now and then, a faulty product slips past the quality control process at the factory.

Related: Circuit Breaker Is On, But No Power To Outlet

FAQs

Here are some of the more common questions about breakers. I’ve given concise answers here for convenience. For more detail, see the above article and associated links.

What happens when a circuit breaker goes bad?

When a circuit breaker fails, it can happen in four basic ways:

  • It doesn’t trip when it’s supposed to
  • It trips more often than it should
  • It won’t reset at all
  • It won’t turn off

I’ve seen all four situations over the course of my career.

Can a circuit breaker go bad without tripping?

Yes. Though very uncommon, a breaker can fail to trip when it is supposed to, causing an overheated circuit. There is usually no way to know until it is too late.

Certain brands of breakers have been banned over the years due to this danger. Higher standards are in place nowadays, so only specific older brands are known to be a concern. FPE & Zinsco panels are the biggest red flags.

What are the symptoms of a bad circuit breaker?

As noted above, there are a few tell-tale things that are typical signs of a bad circuit breaker.

  • If it trips often and you have thoroughly checked the circuit for shorts and overload, it’s likely bad.
  • If you can’t reset it, that could indicate failure. Though, it could be a circuit issue.
  • If you can’t turn it off manually, it is bad.

How to tell if a GFCI circuit breaker is bad

GFCI breakers are a little more difficult to evaluate because they have extra sensors incorporated into them.

However, many indicators are similar to a regular breaker.

  • If the breaker is on, but you have no power on the circuit, the breaker could be bad. Test for voltage with a multimeter right at the breaker terminal to be sure.
  • If pressing the small TEST button on the breaker does not trip it, it is bad.
  • If it is tripped or off, and won’t reset without a wire connected to it, it is bad.
  • If it trips frequently, it could be bad. However, it may be detecting a ground fault on the circuit somewhere. That means it’s doing its job. Find and fix the ground fault.
gfci breaker closeup

What causes a circuit breaker to go bad?

Frequent tripping and resetting of the breaker can wear it out and cause premature failure. This can be a result of chronic overloading of the circuit, or a recurring short circuit.

Also, using the breaker as a switch (flipping it several times a day) can eventually wear it out. Some breakers are rated as switches; others are not.

A power surge could fry the innards of some breakers, depending on their sensitivity and type. Lightning can be responsible for this.

Can a bad circuit breaker cause the lights to flicker?

If the breaker is right on the verge of failure, it is possible that it can cause lights to flicker. This, however, is not very common.

Usually, flickering lights is caused by a bad connection somewhere in the circuit – or at the light itself.

On the other hand, lights that fluctuate slightly in brightness, are typically caused by overload on the circuit.

For example, if you plug a vacuum into a nearly full circuit, you may see the lights dim briefly when you hit the ON switch. The vacuum motor draws an extra amount of amperage at startup, briefly overtaxing the circuit.

Final Thoughts

Testing for a bad circuit breaker is fairly easy to do. If you follow the steps above that apply to your situation, you should be able to determine with confidence whether your breaker is still good or not.

Remember to always match a replacement breaker exactly to the old breaker. Never upsize the breaker.

When working in the panel, when possible, always turn off the MAIN breaker. It’s not worth the risk.

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