# Circuit breakers go bad?
**URL:** https://boards.straightdope.com/t/circuit-breakers-go-bad/829856
**Category:** Factual Questions
**Created:** [February 19, 2019, 9:21pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856 "2019-02-19T21:21:02Z")
**Posts on this page:** 17
**Page:** 1
### Author:  [@markn\_1](https://boards.straightdope.com/u/markn_1)
#### Post date: [February 19, 2019, 9:21pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/1 "2019-02-19T21:21:02Z")
For the first time in my life I’ve had a circuit breaker fail. I didn’t even know they did that. The breaker tripped, I tried resetting it but it felt “loose” and wouldn’t click into the on position, and the circuit remained dead. I got a replacement breaker, swapped it in, and now the circuit is working again.
So what actually happens inside the thing when a breaker goes bad?
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### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [February 19, 2019, 9:29pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/2 "2019-02-19T21:29:35Z")
Can’t answer the question, but share the experience.
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### Author:  [@Leaffan](https://boards.straightdope.com/u/Leaffan)
#### Post date: [February 19, 2019, 9:34pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/3 "2019-02-19T21:34:39Z")
All electromechanical things fail eventually.
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### Author:  [@Folly](https://boards.straightdope.com/u/Folly)
#### Post date: [February 19, 2019, 9:38pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/4 "2019-02-19T21:38:54Z")
Here’s a youtube autopsy of a British one, by your friend and mine, Big Clive.
[ ](https://www.youtube.com/watch?v=WcxISVcIpCA)
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### Author:  [@Shoeless](https://boards.straightdope.com/u/Shoeless)
#### Post date: [February 19, 2019, 9:59pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/5 "2019-02-19T21:59:00Z")
Just had an electrician out today to replace a breaker. I believe his exact words were “it was pretty much melted.”
Apparently when they built our house, they put all the GFI outlets (bathrooms, garage, outside) on the same 15A circuit. We discovered this when my wife bought a plug-in hybrid last summer, and kept tripping the breaker every time she dried her hair while the car was plugged in.
Got to the point in the last couple weeks that the breaker would trip from either the hair dryer or the car. We made an appointment with an electrician to come out and replace the breaker for the bathrooms and add a new one for the garage. A couple days later, the breaker tripped just from turning the bathroom lights on. So we just left it off until the electrician got here today.
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### Author:  [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)
#### Post date: [February 19, 2019, 10:23pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/6 "2019-02-19T22:23:18Z")
Circuit breakers do wear out, just like anything else. Generally takes decades, though.
A couple of things can increase the chances of early failure:
- persistent full load/overload on the circuit – not tripping the breaker, but just below that point.
- frequent use of the breaker. They aren’t designed to be used as on/off switches for the circuit, and using them that way will wear them out early.
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### Author:  [@K2500](https://boards.straightdope.com/u/K2500)
#### Post date: [February 19, 2019, 11:33pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/7 "2019-02-19T23:33:33Z")
There’s a couple little cam/lever/springy things inside that let the breaker trip on either thermal or magnetic. Thermal for overload and magnetic for shorts.
Probably something gives up at “B” or to the bottom right of “D”
[pictured here](https://www.google.com/search?client=ms-android-verizon&source=android-browser&ei=_I9sXPDOKeK-jwSTiJGoDA&q=thermal+magnetic+circuit+breaker+diagram&oq=thermal+megneic&gs_l=mobile-gws-wiz-serp.1.0.0i71l5.0.0..6264...0.0..0.0.0.......0.usVgkER8ZsE#imgrc=6Z9tscKgpnzh8M:)
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### Author:  [@dougrb](https://boards.straightdope.com/u/dougrb)
#### Post date: [February 19, 2019, 11:34pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/8 "2019-02-19T23:34:36Z")
> [@Tim\_T-Bonham.net](#):
>
> Circuit breakers do wear out, just like anything else. Generally takes decades, though.
One of my first jobs while studying electrical engineering in college was at a Square D circuit breaker plant. My job was to apply direct short circuits to breakers and make sure they would continue to function properly. It’s amazing the beating they can take.
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### Author:  [@GaryM](https://boards.straightdope.com/u/GaryM)
#### Post date: [February 20, 2019, 12:00am UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/9 "2019-02-20T00:00:17Z")
> [@Shoeless](#):
>
> Just had an electrician out today to replace a breaker. I believe his exact words were “it was pretty much melted.”
>
> Apparently when they built our house, they put all the GFI outlets (bathrooms, garage, outside) on the same 15A circuit. We discovered this when my wife bought a plug-in hybrid last summer, and kept tripping the breaker every time she dried her hair while the car was plugged in.
>
> Got to the point in the last couple weeks that the breaker would trip from either the hair dryer or the car. We made an appointment with an electrician to come out and replace the breaker for the bathrooms and add a new one for the garage. A couple days later, the breaker tripped just from turning the bathroom lights on. So we just left it off until the electrician got here today.
Did you consider installing a GFCI breaker and eliminating the GFCI receptacles?
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### Author:  [@JohnGalt](https://boards.straightdope.com/u/JohnGalt)
#### Post date: [February 20, 2019, 1:58am UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/10 "2019-02-20T01:58:23Z")
They certainly do fail and do get recalled. I rewired our 1917 house to replace knob-and-tube wiring, and to bring it up to code I had to install some arc fault circuit interrupters / circuit breakers. I installed a pair of them, and one would trip frequently and randomly. Only by swapping the breakers did I conclude it wasn’t my wiring that was at fault, but a bad breaker. A Google search for breaker recalls brings up lots of results.
I returned mine to where I bought it, Home Depot, and they immediately exchanged it with no questions asked, some six months after I bought it. It seemed like they had more than just a few get returned.
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### Author:  [@Shoeless](https://boards.straightdope.com/u/Shoeless)
#### Post date: [February 20, 2019, 4:02am UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/11 "2019-02-20T04:02:04Z")
> [@GaryM](#):
>
> Did you consider installing a GFCI breaker and eliminating the GFCI receptacles?
Didn’t really give it much thought. We just knew we had to get the garage on a separate circuit.
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### Author:  [@kayaker](https://boards.straightdope.com/u/kayaker)
#### Post date: [February 20, 2019, 1:19pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/12 "2019-02-20T13:19:42Z")
I replaced a failed circuit breaker once. I am not an electrician, but I am sometimes a cheapskate. It was scary. Luckily no one was watching; my every move was choreographed and precise. And I was sweating.
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### Author:  [@BrotherCadfael](https://boards.straightdope.com/u/BrotherCadfael)
#### Post date: [February 20, 2019, 1:26pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/13 "2019-02-20T13:26:45Z")
When they fail, do they “fail safe”? That is, when they fail, do they cut power, or, when they fail, will they no longer cut power, no matter how much power is drawn? (You can see that the latter is a Very Bad Thng.)
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### Author:  [@engineer\_comp\_geek](https://boards.straightdope.com/u/engineer_comp_geek)
#### Post date: [February 20, 2019, 4:14pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/14 "2019-02-20T16:14:53Z")
> [@BrotherCadfael](#):
>
> When they fail, do they “fail safe”?
They don’t always fail safe.
Most of the time they will, but the key word there is “most”. The most common types of failures are in the latching mechanism, so they’ll trip at lower currents than they are supposed to trip or they’ll fail to stay closed when you try to reset them.
They can fail in such a way that they won’t open, or they can fail in a way that makes them slow to open, slow enough that the fault current that flows can do a lot of damage.
For example, you can have a failure in the spring, and that could cause the breaker to stay closed when it should be opening the circuit. If you have a lot of arcing internally you can also basically spot weld the contacts together so that the breaker also won’t open when it should.
As **[Tim@T-Bonham.net](mailto:Tim@T-Bonham.net)** said upthread, the two things that can drastically shorten the life of your breakers are consistently high currents just below the trip threshold, which cause overheating and damage, and excessive tripping. Every time a breaker trips you end up with some arcing of the contacts, which builds up carbon deposits on those contacts. You can end up with poor conductivity between the contacts, resulting in hot spots and overheating, or again, you could possibly end up spot welding the contacts together when you close the breaker.
More often than not though, the breaker just fails to stay closed, at least in my experience.
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### Author:  [@gotpasswords](https://boards.straightdope.com/u/gotpasswords)
#### Post date: [February 20, 2019, 6:20pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/15 "2019-02-20T18:20:39Z")
> [@BrotherCadfael](#):
>
> When they fail, do they “fail safe”?
Usually, but there are a couple well-known exceptions to this. Zinsco and Federal Pacific were two of the worst offenders at not tripping out when overloaded. Hopefully by now there’s not too many of either brand still in use.
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### Author:  [@Sparky812](https://boards.straightdope.com/u/Sparky812)
#### Post date: [February 20, 2019, 6:30pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/16 "2019-02-20T18:30:27Z")
I frequently deal with breakers that are subjected to excessive tripping and overloaded circuits. They usually become weak and loose and will not stay reset. They also may arc, overheat, melt, etc… as parts wear out.
It’s unbelievable how many people will trip a breaker and then go flip it back on without a second thought as to why it tripped. It’s a safety device not a light switch. You need to eliminate the cause of the overcurrent before resetting a breaker or someone’s in for a shock.
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### Author:  [@ToughLife](https://boards.straightdope.com/u/ToughLife)
#### Post date: [February 20, 2019, 10:20pm UTC](https://boards.straightdope.com/t/circuit-breakers-go-bad/829856/17 "2019-02-20T22:20:04Z")
One other possibility that hasn’t been mentioned.
- Incorrect resetting\*.
A lot of circuit breakers have three positions: ON, OFF,TRIPPED.
Some even have an indicator window showing that CB has been tripped.
TRIPPED position is in between ON and OFF position.
To reset the CB you need to bring it down to OFF position first
and then bring it to the ON position.
It may stay ON if the fault is gone for some reason or it may trip again,
In any case investigation is warranted.