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 or making a Paypal contribution here: paypal.me/SupportTMC

Circuit breaker popping during 240v charging

Discussion in 'Model S: Battery & Charging' started by robaross, May 10, 2013.

  1. robaross

    robaross P4550

    Joined:
    Aug 8, 2011
    Messages:
    122
    Location:
    SFL
    Yesterday my 240V circuit breaker popped after charging at 36 amps from 130 miles to 230 miles. Reset, then popped again at 251 miles. Service says it's my line but this did not occur 1st 3 months and is now happening more frequently. Is it my line or the UMC or adapter?
     
  2. jeffro01

    jeffro01 Active Member

    Joined:
    Jan 30, 2013
    Messages:
    1,160
    Location:
    SF Bay Area
    Could be any one of them, it also could be the breaker itself. While not common, it's certainly not unheard of for breakers to "fail". You might look there as well.

    Jeff
     
  3. Zextraterrestrial

    Joined:
    Mar 11, 2010
    Messages:
    3,636
    Location:
    Humboldt/Los Altos
    I had the 'free' outlet that I use on occasion pop the breaker twice during a sunny warm day ~ 75F
    It never had problems before and didn't during the last time I charged for 4 hrs after dusk

    Did you have it dialed back to 36A or is that just what it was pulling?
     
  4. MichaelS

    MichaelS Member

    Joined:
    Aug 8, 2012
    Messages:
    226
    Location:
    Hayward CA
    Is it a 40A breaker? How old is the breaker? Does only one side pop, or both L1 and L2? Does the breaker feel warm when it trips?

    Breakers do wear out and get weaker as they age.

    Also 36A is pretty close to the breaker rating. Normally a 40A circuit should not have more than 30A load.
     
  5. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

    Joined:
    Sep 23, 2012
    Messages:
    1,192
    Location:
    San Diego
    yep.. it's likely a surge onto a 40amp breaker. check your wiring, and see if a 50 amp breaker is feasible... that's what you need
     
  6. Cosmacelf

    Cosmacelf Active Member

    Joined:
    Mar 6, 2013
    Messages:
    3,399
    Location:
    San Diego
    The OP didn't say what size breaker he had, but given he is charging at 36 amps, then maybe he does only have a 40 amp breaker. If so, 32 amps should be the max. If he has a 50 amp breaker, then there is a fault somewhere. If you feel up to it, swapping out the breaker is relatively easy. New breakers cost about $10.
     
  7. DCWitt

    DCWitt Member

    Joined:
    Nov 23, 2012
    Messages:
    172
    Location:
    Watseka, IL
    Also, make sure the lugs are tight where the wire connects to the breaker.
     
  8. robaross

    robaross P4550

    Joined:
    Aug 8, 2011
    Messages:
    122
    Location:
    SFL
    Guess I wasn't clear. This is a new line installed for the car in January. It's a double gang breaker, new, rated 50 amps on 6/8 gauge wire. I had no trouble initially charging at 40 amps, 242 volts. Problem is recent so I dialed back to 36 amps. Still tripping the breaker. Electrician is coming tomorrow to check. If not his problem I will request a new UMC and adapter from Tesla.
     
  9. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

    Joined:
    Jun 21, 2012
    Messages:
    7,019
    Breakers do go bad. I'd be measuring the current while you're charging, then consider replacing the breaker as long as the current draw was within spec. Sounds like you have the right people working it. Good luck.
     
  10. CliffG

    CliffG Member

    Joined:
    Feb 10, 2014
    Messages:
    245
    Location:
    New Jersey
    What did you find out?

    I have the same problem, starting 6 months after the 14-50 was installed and started using it. I've got #4 AL wire to the outlet in my garage; when it first started happening, around June, I managed to get it to function by dialing down to 20 amps. Now even that causes the breaker to trip. The outlet and UMC are cool to the touch, but the breaker is very warm. During warm weather it's bearable - I can charge at work or a nearby SC, but I like being able to prewarm the car in the winter. Plus, not knowing why it's happening feels hazardous.
     
  11. islandbayy

    islandbayy Active Member

    Joined:
    Feb 25, 2013
    Messages:
    2,015
    Location:
    Greendale, Wisconsin
    Being that your using Aluminum wire, it is very possible the lugs on the breaker (and to be on the safe side, the lugs in your box in the garage) may need to be re-torqued/tightened down again. The breaker should not be getting more then just warm. Is it getting hot even at 20 amps? If so, either the breaker is defective or the lugs need to be retightened.
     
  12. CliffG

    CliffG Member

    Joined:
    Feb 10, 2014
    Messages:
    245
    Location:
    New Jersey
    yeah, that's what I was thinking.

    I honestly don't know if it was getting hot before this week - I've only used it that way a couple of times over the last 5 months (as noted - charging at work was pretty convenient), but it was a bit hot when I thought to check it when it tripped earlier this week. Haven't used it since. Guess I'll be waiting for the electrician (or someone like him) <snicker/>
     
  13. richkae

    richkae VIN587

    Joined:
    Jan 15, 2008
    Messages:
    1,917
    Imagine that you are the engineer who designs a circuit breaker. You do everything you can to make it to fail in one way, and one way only. That is to trip at too low an amperage. Failing that way is inconvenient. Failing the other way is a disaster.

    Having to replace or adjust a circuit breaker occasionally because of this is exactly what you want.
     
  14. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

    Joined:
    Jun 21, 2012
    Messages:
    7,019
    I'll pay dollars to doughnuts the lugs are loose. Re-torque the connections and see if that fixes it, otherwise replace the breaker.
     
  15. linkster

    linkster Member

    Joined:
    Apr 22, 2013
    Messages:
    989
    Location:
    USAX2
    Flash,

    Might some No-Ox be worthwhile in addition to re-torquing for CliffG's AL wiring?
     
  16. islandbayy

    islandbayy Active Member

    Joined:
    Feb 25, 2013
    Messages:
    2,015
    Location:
    Greendale, Wisconsin
    Yes it is, however a decent electrician would have put it on from the get go and should not need any more, though, their are many bad electricians who don't use any at all. I hate aluminum wire :-( I always splurge the extra few dollars for copper.
     
  17. tga

    tga Active Member

    Joined:
    Apr 8, 2014
    Messages:
    2,201
    Location:
    New Hampshire
    If the AL wire was installed without NOALOX, I'd clip the stripped ends, re-strip, scrape, and apply NOALOX. I would not apply it to existing stripped, dry AL wire - it's already oxidized.
     
  18. Barry

    Barry Member

    Joined:
    Aug 9, 2013
    Messages:
    780
    Location:
    Colorado
    Nothing a little emery cloth couldn't fix.
     
  19. tga

    tga Active Member

    Joined:
    Apr 8, 2014
    Messages:
    2,201
    Location:
    New Hampshire
    Might be worth a try. Although everytime I've seen a pro do it, they've clipped/stripped/scraped to expose new, clean wire.
     
  20. dhrivnak

    dhrivnak Active Member

    Joined:
    Jan 8, 2011
    Messages:
    2,150
    Location:
    NE Tennessee
    My understanding is that many breakers trip thermally which is an indicator but an exact measurement of current. So warmer temperatures and lose lugs can exasperate the problem. I was at a KOA and while in theory they had 50 amp breakers but I could not charge above 34 amps without tripping, normally after 20+ minutes. When at my home and breakers I can charge at 46 amps for hours with no issue.
     

Share This Page