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Thread: How many times can a breaker trip before it should be replaced?

  1. #1
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    How many times can a breaker trip before it should be replaced?

    Does anyone have information on the best way to test a circuit breaker to see if it is bad? How many times can a breaker trip before it should be replaced? I'm sure the manufactures have a rated duty cycle for each breaker. Does anyone know where to find this information. I have tried several places and have only found the amount when used as a switch but not if it trips.

  2. #2
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    I'm curious how this question came up. Do you have a breaker that has tripped so many times that you are afraid it is worn out? If so, perhaps you should be looking for the cause instead of worrying about the effect.

    Other than that, why would the number of trip operations be different than the number of switch operations? In my opinion, they should be the same.

  3. #3
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    Quote Originally Posted by drbond24 View Post
    . . . why would the number of trip operations be different than the number of switch operations? In my opinion, they should be the same.

    I do not know the answer to the OP's question. But I do believe that the act of tripping on overcurrent imposes a harsher transient upon a breaker than the act of being manually opened.
    Charles E. Beck, P.E., Seattle
    Comments based on 2014 NEC unless otherwise noted.

  4. #4
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    Quote Originally Posted by keepincool View Post
    Does anyone have information on the best way to test a circuit breaker to see if it is bad?
    Primary injection and compare to trip curves.


    Quote Originally Posted by keepincool View Post
    How many times can a breaker trip before it should be replaced? I'm sure the manufactures have a rated duty cycle for each breaker. Does anyone know where to find this information. I have tried several places and have only found the amount when used as a switch but not if it trips.
    Depends on what type of breaker you are talking about, most are rated for around 2000 operations or 2-3 fault interuptions before they should be reconditioned. I have the specs for about every breaker out there. just tell me the type.

  5. #5
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    It really depends on your breaker construction and amp rating. Breakers built to NEMA and UL are different than those built to ANSI standards

    Most molded case circuit breakers are rated for 1000's of mechanical operations and only 2 full rated fault interruptions. Overloads (even upto 10x) are faults that do not drastically shorten the life of the breaker. But without a fault analysis and identification of the fault, how do you know how much current the breaker actually interrupted.
    Just because you can, doesn't mean you should.

  6. #6
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    The question came up over a 50amp SquareD Homeline breaker, the A/C was causing the breaker to trip frequently and the homeowner indicated that he had reset the breaker numerous times. After recommending the replacement of the breaker the question was posed "How many times can it trip before it must be replaced?" I didn't have the specific answer, hence my question to the forum.

    I am understanding from the previous post that most molded case breakers can be switched (mechanical operation) approx 1,000 times but can only trip (fault interruption) 2-3 times before replacement is recommended.

    Thanks for the info.

  7. #7
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    From my experience i think it mainly depends on how high an overload a breaker is being tripped on. I have seen breakers trip one time on a direct short and never work again! Just a guess(and you know what they say about opinions), on a slowly applied overload--maybe twenty trips before the trip setpoint has a lower trip capability--again, thats my guess:rolleyes:!

  8. #8
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    What really strikes me when reading this question is....
    The load supplied from the breaker. AIR CONDITIONING. Most of us are freezing, and this guy is replacing AC circuit breakers.
    Instructor, Industry Advocate

  9. #9
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    Quote Originally Posted by Pierre C Belarge View Post
    What really strikes me when reading this question is....
    The load supplied from the breaker. AIR CONDITIONING. Most of us are freezing, and this guy is replacing AC circuit breakers.
    GREAT observation Pierre! :smile:
    Lou (wannabe economist)

    If you relentlessly pursue perfection, you will eventually catch excellence.

  10. #10
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    Quote Originally Posted by charlietuna View Post
    ...before the trip setpoint has a lower trip capability--again, thats my guess:rolleyes:!
    The trip point never varies with operations unless you have operated it enough times that the breaker latching mechanism is becoming worn out

    On a small molded case circuit breaker like the 50A mentioned above, the criteria is: 6000 full load amp operations and 4000 zero amp operations for a total of 10,000 operations. So unless you have a very poorly manufactured breaker, that is well outside the UL operations parameters - most breakers will not wear out due to switching. Its overload performance is: 50 operations at 6x rated current (or 150A which ever is lower) so it is possible for a breaker to wear out electrically if it is subject to regular "instantaneous" tripping.
    Just because you can, doesn't mean you should.

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