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  1. #1
    Join Date
    Feb 2008
    Posts
    4

    50 amp circuit breaker heating

    I have a 42amp heat pump load on on both leads of a 50 amp double breaker, 240 vac. Lug connections are tight. After a year or so of no problems, this breaker has started to trip occasionally. The breaker heats up but not so hot that to touch is painful. Wires (awg 8, I think) do not appear to be heated.
    Is this normal for this load/breaker ratio?
    Any help will be appreciated.
    Irby

  2. #2
    Join Date
    Jul 2001
    Location
    Gold Coast of Connecticut
    Posts
    4,615
    I would call an electrician.
    Aire Serv of SW Connecticut- Gas heat, dual fuel and central a/c systems installed and serviced

  3. #3
    Join Date
    Jul 2007
    Location
    Northeast Ohio
    Posts
    17
    Circuit Breakers should not be operated above 80% of their rated load. Call the electrician.

  4. #4
    Join Date
    Aug 2002
    Location
    Southold.calm
    Posts
    5,838
    Solid or Stranded?

    Length of run?

    Actual incoming Voltage?

    These and several others ?’s need to be answered before an answer can be given.

    Breakers and wires should not be warm or hot.

    Bottom line Call an electrician


    http://www.powerstream.com/Wire_Size.htm

  5. #5
    Join Date
    Feb 2003
    Location
    Huntsville,AL
    Posts
    4,125
    wires in attic?
    in magnetic conduit?
    copper | aluminum?
    several trippings = new one!!!
    Last edited by cem-bsee; 02-27-2008 at 08:01 PM.
    harvest rainwater,make SHADE,R75/50/30= roof/wall/floor, use HVAC mastic,caulk all wall seams!

  6. #6
    Join Date
    Jan 2004
    Location
    Lancaster PA
    Posts
    68,308
    42 amps when you checked it.
    Could be spikes that are tripping it.
    42 amps is too much for a constant load on a 50 amp breaker.
    Contractor locator map

    How-to-apply-for-Professional

    How many times must one fix something before it is fixed?

  7. #7
    Join Date
    Dec 2002
    Location
    SouthEast NC ICW & Piedmont Foothills
    Posts
    7,635
    1- your breaker is oversized for the wire

    2-42A ought to be on a tad bigger breaker= bigger wire


    You gonna need an electrician
    It`s better to be silent and thought the fool; than speak and remove all doubt.

  8. #8
    Join Date
    Feb 2008
    Posts
    4

    50 amp circuit breaker heating

    Thanks for all of the quick replies. I'm going to check out all of the questions you asked and get back with the info.
    Irby

  9. #9
    Join Date
    Nov 2007
    Location
    Washington State (on the Peninsula)
    Posts
    80

    Call Electrician !

    Quote Originally Posted by irbyjr View Post
    I have a 42amp heat pump load on on both leads of a 50 amp double breaker, 240 vac. Lug connections are tight. After a year or so of no problems, this breaker has started to trip occasionally. The breaker heats up but not so hot that to touch is painful. Wires (awg 8, I think) do not appear to be heated.
    Is this normal for this load/breaker ratio?
    Any help will be appreciated.
    Irby
    You need an electrician ASAP!
    That should have a 60 A breaker with 4awg thhn.
    Without knowing what you data plate calls for circut ampicity and using your 42 amps stated in your post ...
    42 x 125% = 52.5 you ned a 60 A breaker ...
    Now with a 60 A breaker you need 4 awg thhn.
    per NEC table 310.16 60 degree column.

  10. #10
    Join Date
    Jul 2000
    Location
    Northern Wisconsin
    Posts
    2,032
    Hopefully by now you've quit checking and have called a licensed electrician.
    Use the biggest hammer you like, pounding a square peg into a round hole does not equal a proper fit.

  11. #11
    Join Date
    Feb 2008
    Posts
    4

    50 amp breaker heating

    Thanks again for your advice and warnings. Actually, the circuit was deactivated before I posted the original question.
    Irby

  12. #12
    Join Date
    Feb 2008
    Posts
    4

    50 amp breaker heating up

    Seems as though this heat pump had an emergency resistance heater that supposedly had been disconnected long ago, but someone had re-connected it. The room thermostat was set too high on a cold morning and the backup heater did energize, apparently causing the high amperage that slowly heated the breaker. The unit is operating OK now with that backup heater circuit disconnected.
    Thanks for all of your comments.
    Irby

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