TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC
Start a Discussionhttps://teslamotorsclub.com/tmc/tags/

Electrical breaker getting warm

Discussion in 'Model S: Battery & Charging' started by Ormond, Dec 1, 2016.

  1. Ormond

    Ormond Member

    Joined:
    Jul 10, 2016
    Messages:
    366
    Location:
    USA
    The other day I was charging my Model X with the UMC and NEMA 14-50 outlet that I installed at home. I think I was charging at 40 amps. We noticed a buzzing sound coming from the electrical panel. I could also feel heat coming off the closed panel. I unplugged the charger and the buzzing stopped.

    Since that time, I've only been charging while I'm awake so that I can monitor the panel. I also dropped my charging rate to 35 amps. I haven't heard buzzing, but I still feel some heat. I have a 50 amp breaker for the outlet and my panel is full.

    I have the electrician who installed the outlet coming back today. Any ideas or suggestions? Is my panel maxed out? Have you experienced the same conditions while charging?
     
  2. Maximapolak

    Maximapolak Member

    Joined:
    Nov 13, 2016
    Messages:
    472
    Location:
    North NJ / SouthCentral PA
    Maybe the wires aren't tightened enough.
     
    • Helpful x 1
    • Like x 1
  3. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,932
    Location:
    Canada
    ...on the breaker itself. And at the receptacle.

    Does your UMC plug get warm too?

    Or maybe the breaker is bad. Swap for another.
    If an electrician put it in, absolutely call them back and make the problem known.

    Whatever you do, don't change out the breaker for a higher Amp rating. ( = fire)

    Get them to double check the wiring gauge from the panel to the receptacle. It should be a straight run from the panel to plug... no junctions or joins.
     
  4. habanero69

    habanero69 I Dont Need Cialis. I Drive an EV.

    Joined:
    Jul 29, 2016
    Messages:
    387
    Location:
    FLorida
    You shouldn't get any buzzing from the panel. It could be one of the prior posts like lose connection, bad breaker... assuming you are NOT exceeding your panels rating. Your installed should be called back to check.

    I am surprised how hot the UMC cable itself gets when I'm doing a 3-4 hour charge. It is warm enough to almost be uncomfortable at times when handling. Makes me wonder if they are running at the outer limits of the wires/charger.:confused:
     
    • Helpful x 1
  5. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,932
    Location:
    Canada
    UMC handle where it meets the car degrades in making good contact over time, contacts get dirty ... resistance goes up, makes heat.

    Lowering the charging rate (Amperage) helps... but... sometimes you want the speed.

    You can try having the handle contacts cleaned using an appropriate electrical contact cleaner... and also clean the contacts in the charge port on the car. Done this a few times in the life of the car... 2 years now.

    At some point the charger handle gets too hot, and cleaning does not help. Then it's time to replace the charger. Tesla will do this for UMC under warranty of the car, because it comes with the car.
     
    • Helpful x 1
  6. brkaus

    brkaus Active Member

    Joined:
    Jul 8, 2014
    Messages:
    2,123
    I had a new circuit 14-50 put in right under my breaker panel. 14" wire. 50a breaker.

    Tried charging a demo car. Worked for a few minutes, then cut back to 30a. Eventually tripped breaker.

    Reset breaker when I noticed. Started charging and watched carefully. Noticed breaker hot. Heard buzzing sound from breaker. Turned off.

    Put in new breaker next day and all was fine. Guess I got a dud.
     
    • Helpful x 1
  7. Ormond

    Ormond Member

    Joined:
    Jul 10, 2016
    Messages:
    366
    Location:
    USA
    I didn't notice the UMC being hot, but I did notice an odd smell. Maybe something was burning. I quit charging until the electrician arrives.
     
  8. scottm

    scottm Active Member

    Joined:
    Jun 13, 2014
    Messages:
    1,932
    Location:
    Canada
    smart move
     
  9. gregd

    gregd Active Member

    Joined:
    Dec 31, 2014
    Messages:
    1,228
    Location:
    CM98
    What brand of panel do you have? There are some, Zinsco in particular, that are known to fail under load. Really poor design. I have one, and we're replacing it as part of adding the new 14-50 circuit.
     
  10. brucet999

    brucet999 Active Member

    Joined:
    Mar 12, 2015
    Messages:
    2,025
    Location:
    Huntington Beach, CA
    As @gregd posted, there are some bad panels out there. Not only Zinsco, but FPE (Federal Pacific Electric), Bulldog Pushmatic, and a few others. If your electrician simply connected to an existing 50A breaker (from an abandoned stove circuit, for example) it could be a bad breaker. If your panel is one of the failure-prone ones and he installed a new breaker it could be an out-of-box failure (FPE had 40
    % faulty rate) or the panel itself. My old Zinsco panel was arcing at the breaker/bus connection due to pitted metal on the bus bar. I replaced the panel with Square-D before installing my 14-50 circuit.
     
  11. Ormond

    Ormond Member

    Joined:
    Jul 10, 2016
    Messages:
    366
    Location:
    USA
    My panel was made by Challenger Electrical Equipment Corp. and is about 20 years old. The electrician cam out yesterday and moved some of the breakers around so that the 14-50 outlet had two spaces by itself. The breaker itself still gets hot (175* ) while charging at 40 amps., but it's much better than it was. I may drop down to 35 amps. I am still going to keep a close watch on the panel. The UMC didn't get hot, just warm.

    I appreciate everyone's help.
     
  12. ColdRauv

    ColdRauv Member

    Joined:
    Oct 29, 2015
    Messages:
    62
    Location:
    Minnesota
    Please monitor the temperature of this breaker. If you are measuring temperature at the wire termination, 175 degrees is on the high end of the UL489 testing range, but OK. If you are measuring the temperature on the face of the nonmetallic case, 175 is within 10 degrees of being too hot and indicates a problem. Has this breaker tripped on you yet? High heat will trip a breaker at a lower current.
     
  13. DarkMatter

    DarkMatter Member

    Joined:
    Jul 13, 2016
    Messages:
    548
    Location:
    Olympia, WA
    If your panel is getting that hot I would not trust it with a high continuous load such as EV charging. If I were in your spot I would switch to charging with a 14-30 so you limit to 24 amps, or maybe buy the Canadian 14-50 adapter which automatically limits to 32 amps instead of 40.

    Long term you should put in a panel which is not obsolete. Breakers for Challenger panels are listed as an obsolete type. Of course that can be moderately expensive so I understand if you're in no hurry to do it. Limit the current in the meantime until it doesn't get so hot. Having to replace a panel on short notice because of a burned bus bar is no fun. BTDT.
     
  14. Ormond

    Ormond Member

    Joined:
    Jul 10, 2016
    Messages:
    366
    Location:
    USA
    I'll drop it to 32 amps. I was measuring the temperature of the breaker itself.
     
  15. tga

    tga Supporting Member

    Joined:
    Apr 8, 2014
    Messages:
    2,711
    Location:
    New Hampshire
    IMHO, 175 is too hot. Something is wrong, and you should get it checked out. My old solar system routinely pushed 32-34A through a 40A backfeed breaker (GE). It would get noticeably warm, but I could hold my hand on it without discomfort. I think I was seeing ~105F with an IR thermometer.
     
  16. Ormond

    Ormond Member

    Joined:
    Jul 10, 2016
    Messages:
    366
    Location:
    USA
    I'll measure it again and drop the amps. I don't mind charging more slowly. I may also change electricians :)
     

Share This Page