User Tag List

Page 1 of 3 1 2 3 LastLast
Results 1 to 10 of 23

Thread: Do breakers ever get "weak"

  1. #1
    Join Date
    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
    Posts
    5,780
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)

    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. #2
    Join Date
    Dec 2006
    Location
    Chapel Hill, NC
    Posts
    34,757
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote 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



  3. #3
    Join Date
    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
    Posts
    5,780
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    Quote 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"

  4. #4
    Join Date
    May 2014
    Location
    Marlborough, Massachusetts USA
    Posts
    400
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    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.:

  5. #5
    Join Date
    Jun 2004
    Location
    Cherry Valley NY, Seattle, WA
    Posts
    5,780
    Mentioned
    2 Post(s)
    Tagged
    0 Thread(s)
    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"

  6. #6
    Join Date
    Dec 2006
    Location
    Eastern Oregon
    Posts
    3,788
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    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.

  7. #7
    Join Date
    Jun 2003
    Location
    NE (9.06 miles @5.9 Degrees from Winged Horses)
    Posts
    11,273
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Customers that keep turning them on after repeated trips without having things investigated are the biggest problem.
    Tom
    TBLO

  8. #8
    Join Date
    Mar 2019
    Location
    Vancouver Canada BC
    Posts
    16
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    Quote 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

  9. #9
    Join Date
    May 2005
    Location
    Richmond, Virginia
    Posts
    25,539
    Mentioned
    1 Post(s)
    Tagged
    0 Thread(s)
    Quote 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.
    Code references based on 2005 NEC
    Larry B. Fine
    Master Electrician
    Electrical Contractor
    Richmond, VA

  10. #10
    Join Date
    Jul 2013
    Location
    Resting under the Major Oak UK
    Posts
    1,343
    Mentioned
    0 Post(s)
    Tagged
    0 Thread(s)
    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.
    The reports of my death are greatly exaggerated.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •