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Do breakers ever get "weak"

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    Do breakers ever get "weak"

    ...as in trip too soon or easily? This is one of those things people ask or say a lot, but I can't recall actually seeing a single instance in my career.
    Ethan Brush - East West Electric. NY, WA. MA

    "You can't generalize"

    #2
    Originally posted by electrofelon View Post
    ...as in trip too soon or easily? This is one of those things people ask or say a lot, but I can't recall actually seeing a single instance in my career.

    Yes they do. I have replaced at least 2 main 200 amp breakers one of which was tripping with less than a 60 amp load
    They say I shot a man named Gray and took his wife to Italy
    She inherited a million bucks and when she died it came to me
    I can't help it if I'm lucky

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      #3
      Originally posted by Dennis Alwon View Post
      Yes they do. I have replaced at least 2 main 200 amp breakers one of which was tripping with less than a 60 amp load
      Were they old or relatively new?
      Ethan Brush - East West Electric. NY, WA. MA

      "You can't generalize"

      Comment


        #4
        I use the term, for lack of a better word, "tired".
        When describing a CB thst just can't handle the continuous load it used to carry.:

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          #5
          What do you think causes the premature trip, the mag or thermal component?
          Ethan Brush - East West Electric. NY, WA. MA

          "You can't generalize"

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            #6
            The contacts get worn, creating high resistance, which creates excessive heat and tricks the breaker into thinking there is an overload condition.

            I've replaced 3 800's in the last couple years at one customers facility for this reason.

            A FOP test will show this.

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              #7
              Customers that keep turning them on after repeated trips without having things investigated are the biggest problem.
              Tom
              TBLO

              Comment


                #8
                Originally posted by Cow View Post
                ...

                A FOP test will show this.
                Sorry, I’m having a hard time figuring this one out. What’s an FOP test?


                Sent from my iPhone using Tapatalk

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                  #9
                  Originally posted by pjones View Post
                  Sorry, I’m having a hard time figuring this one out. What’s an FOP test?
                  FOP = Fall Of Potential

                  It means measuring the voltage between the line and load terminal of one pole at a time. You're looking for voltage drop where there shouldn't be any. In theory, there should be zero volts across a closed switch or breaker.

                  I would check the line current with a clamp-on ammeter.
                  Master Electrician
                  Electrical Contractor
                  Richmond, VA

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                    #10
                    One of my worries is not a breaker being a bit twitchy in its old age and opening too early but not opening at all. A breaker has sat there for years minding its own business, not troubling anyone until it has to wake up and actually do what it’s supposed to do.

                    Two scenarios diametrically opposed.
                    [COLOR=#000000]The reports of my death are greatly exaggerated.[/COLOR]

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                      #11
                      Originally posted by electrofelon View Post
                      Were they old or relatively new?

                      Old ones but I have seen some not function right out of the box.
                      They say I shot a man named Gray and took his wife to Italy
                      She inherited a million bucks and when she died it came to me
                      I can't help it if I'm lucky

                      Comment


                        #12
                        Originally posted by pjones View Post
                        Sorry, I’m having a hard time figuring this one out. What’s an FOP test?


                        Sent from my iPhone using Tapatalk
                        You need a fairly good meter with a mili volt range. Multipole breakers with the same load should have approximately the same VD across the Line 1 to Load 1, etc. 100mv or less.

                        Zero volt drop would mean zero load to me.
                        Tom
                        TBLO

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                          #13
                          Anything that creates undesired heat within is going to increase the possibility of tripping on thermal, can even be heat that originates at a termination or bus connection and is conducted to interior of the unit.
                          I live for today, I'm just a day behind.

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                            #14
                            Originally posted by kwired View Post
                            Anything that creates undesired heat within is going to increase the possibility of tripping on thermal, can even be heat that originates at a termination or bus connection and is conducted to interior of the unit.
                            I could see that, but what isn't clear to me is how the mag function would go bad to make it trip early.
                            Ethan Brush - East West Electric. NY, WA. MA

                            "You can't generalize"

                            Comment


                              #15
                              Originally posted by Dennis Alwon View Post
                              Old ones but I have seen some not function right out of the box.
                              I guess I am lucky. Can't ever remember getting a bad breaker out of the box, other than maybe one or two that wouldn't latch closed. Can't ever remember one being overly sensitive.
                              Ethan Brush - East West Electric. NY, WA. MA

                              "You can't generalize"

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