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NEMA 14-50 Plug Meltdown / Near Fire

Discussion in 'Model 3: Battery & Charging' started by Jaywlker, Jun 8, 2019.

  1. Jaywlker

    Jaywlker Member

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    #1 Jaywlker, Jun 8, 2019
    Last edited by a moderator: Jun 10, 2019
    DA7EDF7F-FF1C-46C1-BF10-858289F398DB.jpeg 0E61AD2B-2295-4ADC-88FD-7F45DB2604C2.jpeg F10EDBEE-FA26-440F-89E5-F5387402C93E.jpeg

    My main house breaker tripped tonight. Upon investigating, I saw black smoke curling up my garage wall and smelled burning plastic, from where my 14-50 plug is located. Turns out my electrician had installed the plug with a loose black conductor, causing the outlet and plug to meltdown. At this point I am much more relieved than upset because I was able to stop what could have been a disaster. I will be double-checking every connection myself going forward in the install of a HPWC to replace the 14-50! If you smell burning plastic, investigate!

     
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  2. eprosenx

    eprosenx Active Member

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    My gosh! I am so glad that you are OK and your house did not burn down.

    We have seen far too many of these on the forum. It happened to a close friend of mine here locally. I very much appreciate you posting this here as a warning to others. I have been considering gathering all the pictures of the meltdowns I have seen and putting them in one place to underscore to folks how critical it is to do this stuff correctly.

    Some questions for you:

    What brand of receptacle was that? Leviton?

    How long had it been in service?

    Any idea why the branch breaker did not blow? Or did it *also* blow? (what kind of panel do you have? - not like a defective Federal Pacific one?)

    The Wall Connector is a great idea. I have not seen any picture of a melted one yet (not that you could not have a loose terminal on one, but they use better quality clamping connectors than the screws on the low end receptacles).

    Glad you are OK!
     
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  3. SSedan

    SSedan Active Member

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    Thank you for sharing, hopefully you save someone else from a similar or worse experience.
     
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  4. eprosenx

    eprosenx Active Member

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    Btw, perhaps some key takeaways of the story here for others:

    The cheap Leviton receptacles that just use screw terminals rather than clamping style terminals have seen a lot of failures. There is a thread here where someone purchased all the different manufacturer versions they could find and compared them. Leviton was by FAR the worst.

    Proper torque on the terminals is critical.

    The old UMC Gen 1 is more commonly associated with these meltdowns. In part because it draws a full 40 amps, while the new UMC draws 32 amps max.

    The UMC Gen 2 probably would not have let it get this far as it has thermal sensors in the plug head that should have detected this heat buildup.

    This is a good example of why extension cords or 3rd party adapters are bad. The more connection points the more likely for something like this to happen. Especially ones that don’t have effective thermal monitoring.

    It feels like this is worth reporting to the local Fire Marshall and to the receptacle manufacturer. I kind of feel like with the prevalence of EV’s now that Leviton should take their receptacle off the market as it is so vastly inferior to the other brands solutions. It obviously has been fine for intermittent use ranges and RV’s forever, but times are changing...
     
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  5. VT_EE

    VT_EE Active Member

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    There was one wall connector on this forum that failed with some slightly charred insides. The electrician trapped some wire insulation under the lugs which caused problems. Bottom line is the electrician needs to do a good job.
     
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  6. ewoodrick

    ewoodrick Active Member

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    A great example of why people shouldn't be installing these without knowing exactly what they are doing. These things are downright dangerous if not installed correctly
     
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  7. SSedan

    SSedan Active Member

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    How so, he said electrician which implies professional, this was sloppiness/complacency. A careful novice will likely check 3 times.
    When I installed my HCWC I checked the connections repeatedly the first few weeks.

    Professional means "paid to do" not necessarily expert and good at something.
     
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  8. Jaywlker

    Jaywlker Member

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    It was a Leviton brand receptacle. My electrician is a hard-working, experienced tradesman. He was on-the-job training a junior helper. What I presume is that the heavy-duty gauge of the wiring gave the impression that the connection was tight and firm. Both my 50 amp breaker and my whole-house breaker tripped simultaneously, in a conflagration/peak.

    Here is a better photo of the damage done to the receptacle. 4AAFC2F7-7D1B-4EC4-A6A4-984F61F92BFE.jpeg
     
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  9. Jaywlker

    Jaywlker Member

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    #9 Jaywlker, Jun 8, 2019
    Last edited: Jun 8, 2019
    Answers to your questions in bracketed red text below.
    [Thank you! I am blessed and very lucky!]
     
  10. Jaywlker

    Jaywlker Member

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    I agree, and even professionals can make mistakes.
     
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  11. DOCAL

    DOCAL Member

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    This forum really needs a "holy crap" button.

    That's some serious damage, glad the breakers kicked in and stopped anything worse from happening.
     
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  12. amit1947

    amit1947 Member

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    How long have you been charging before this happened? Did it fail months later?
     
  13. eprosenx

    eprosenx Active Member

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    Yeah, on the install I helped with a couple days ago I was annoyed at how nearly impossible it is to see the wires you are terminating in the Wall Connector. I actually emailed Tesla charging support about this and chastised them for not having a strip gauge on the unit (like every breaker does) or even specs on the proper strip length in the manual. Even more importantly they need to engineer the product so you can visually see if you are catching insulation in the lugs. I was barely able to shove my face up in there and verify this.

    So I am not surprised that the main blew in addition to the branch breaker. You had a hard fault on relatively high gauge wire and so the available fault current is pretty big. It might have even been a cross phase leg fault (240v) rather than a single phase fault (120v). The way the breakers work there are two trip mechanisms. One is thermal and requires a bimetallic strip to heat up and bend. The other is electromagnetic and it is designed to clear these kinds of fault quickly. I doubt the outcome would have been any different even if you still had a 175a breaker. It probably would have tripped just the same.

    My guess is that the way this went down was that heat built up and up and up and melted stuff. Eventually wires came into contact which is when the breakers finally tripped. That is what sucks about loose connections. They can produce a ton of heat (which could start a fire) without tripping the breaker.
     
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  14. Jaywlker

    Jaywlker Member

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    It has been enough of a connection to charge over the last 7 months since the electrician installed it. It has probably been generating heat since then, but just failed in spectacular fashion last night. The Leviton receptacle has a joint phillips and flathead slot, and my electrician acknowledged that what likely happened is his apprentice tightened using only a phillips head, without then torquing down using a big flathead. I was using a 40 amp Gen 1 charging cable. Going to install my new HPWC today and tomorrow using 2 gauge wire, and you better believe those connections are going to be properly torqued!!
     
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  15. amit1947

    amit1947 Member

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    I just had my 14-50 installed and will be using the latest mobile charger that comes with the 2019 model 3 (gen 2?).

    I'm trying to be vigilant and touch the charger and side of the socket to check for temperature. Do you think your socket was getting hot or warm to the touch?
     
  16. MidnightRider

    MidnightRider Member

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    What happens is during use it heats up and expands a little, then cools when its off. Gradually loosing the connection over time.
     
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  17. Eno Deb

    Eno Deb Active Member

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    #17 Eno Deb, Jun 8, 2019
    Last edited: Jun 8, 2019
    I'm glad that nothing more serious happened!

    Note that plugging the UMC directly into the outlet rather than using the 3rd party adapter (what kind was it?) might have prevented this, since the UMC has a thermal cutoff sensor.
     
  18. SSedan

    SSedan Active Member

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    That is a UMC 1 adapter not third party.
     
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  19. Eno Deb

    Eno Deb Active Member

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    Ah, OK. I've never seen one first hand.
     
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  20. Jaywlker

    Jaywlker Member

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    By “charger” you mean charging cable with the nema14-50 adapter, right? Yes, my adapter would get warm, but apparently in hindsight it was warmer than it should have been. I chalked it up to the fact that I live in the Phoenix area (Scottsdale) where it is usually warm/hot.
     

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