Model 3

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Seeking advice re: Power outlet melted while charging Model 3

I would appreciate some guidance from the experts in this forum in order to hypothesize what may have cause a new house fire as a result of charging my Model 3. Here is video and photos of what happened to my 20A 125V power outlet: https://photos.app.goo.gl/dQBmedjK9YaXtPEA8


My issue seems similar to a recent thread from Sep 2020 and I I also posted the below as a comment in that thread and tagged 2 users who had some strong points.

I wonder if anyone knows what may have happened (possibly an arc as indicated here in this thread?) and if any recommendations regarding the steps I am taking - see below for details.

For context, I have been using it for 3.5 years to charge first my e-Golf and lately my Model 3.
The fuse started tripping over the past weeks.
This morning I noticed a burning smell and am I glad I've decided to check it - as you can see from the link above I am lucky we didn't have a house fire.

@"TeslaTap.com" I checked your guide https://teslatap.com/articles/tesla-model-3-home-charging-guide/. Very helpful, thank you.

Based on the guide, I have now bought this new 20A 150V outlet: https://www.homedepot.com/p/Leviton-20-Amp-125-Volt-Duplex-Self-Test-Tamper-Resistant-Weather-Resistant-GFCI-Outlet-White-R92-GFWT2-0KW/205997283

I plan to install it and cut down the charging current from my Model 3 as indicated by @stevenmaifert_12203 - but in my case down to max 10A when charging.

Any advice will be greatly appreciated.
For everyone else, check your charging setup.

Comments

  • You need to start with an electrician, as the problem is most definitely with the house/wiring and not the car, and may not be limited to that outlet.

    Otherwise, and to be clear I'm not an expert... you said 20A but that looks like a 15A outlet that fried. What gauge is your wiring? You have fuses and not breakers? Fuses blow and then need to be replaced; breakers trip and then need to be flipped back. They can wear out over time.
  • This looks easy, dont use the stab-in for the wire connections. Use the screw terminals.
  • > @GHammer said:
    > This looks easy, dont use the stab-in for the wire connections. Use the screw terminals.

    +1, GREAT point! Whether you use the stab-in or the screw terminals, bare-metal hot/neutral in direct contact with anything is a red flag. It looks like your line wire was in direct contact with the plastic body of the outlet.

    And also, be careful not to add a 20A outlet on undersized wiring.
  • Thank you @GHammer and @bpr1de.
    I will look for a stab-in option and return the new outlet I have bought as it has screw terminals.
    Regarding the outlet that fried - it shows here 20A indeed: https://photos.app.goo.gl/W7udXo5rbzLBoBve8
    Given this scare, I am trying to do proper due diligence and appreciate the support.
  • > @JLCC said:
    > Thank you @GHammer and @bpr1de.
    > I will look for a stab-in option and return the new outlet I have bought as it has screw terminals.

    No, DO NOT use the stab in, use the screw terminals. For your picture it looks like the failure point was at the stab in. For continuous use like car charging the screw terminals should give a better connection.
  • I do not recall for sure but doesn’t Tesla say not to use a GFI outlet?
  • Ok, a true 20A outlet doesn't have two vertical openings - one of them sort of looks like a + sign. Also, for 20A, you must have 12 gauge wiring (not 14 gauge). Now, Tesla does provide a 20A (really 16A due to 80% derating) adapter for the UMC but it is SO important that the circuit be fully rated for 20A. My wife does 20A (16A) charging at her work because their outlets are fully 20A compliant and it help get that extra "boost" over 15A (12A).
    Looking at your pictures (and like others have said), don't use a GFI outlet and make sure to use the screws (well tightened) - those stab connectors IMHO should have never been allowed in the electrical code.
    Also, it's best to charge on a DEDICATED circuit - if the circuit is shared with other outlets (oh that might have a room heater, hair dryer, etc) that could also be an issue.
  • For those stating it isn't 20A look at the last picture. It clearly shows it's a 20A outlet. https://ibb.co/rF8PR5M
  • While that GFI outlet is RATED for 20A, the only plug that will fit in that outlet is a 5-15. The Tesla 5-15 pigtail will restrict max draw by the car to 12A(80% of 15A) vs the 16A(80% of 20A) that a 5-20 Tesla pigtail will allow.

    Also I would like to not that there are two different kind of "Stab-In's" on certain outlets. There is the stab-in that uses a "spring" to hold the wire in via pressure, and there is Stab-in as shown on this outlet where you push the wire in but you tighten the screw to make the contact pressure. The screw based stab-in is effectively the same as a wrap around the screw type because you are still controlling the pressure via the screw. The spring pressure type suck cause it can wear out over time, or just be crappy in the first place allowing you to just pull out the wire by hand(been there done that).

    Irrespective of the type of connection here, there was obviously some heat buildup for whatever reason. There also may have been a general failure of the GFI outlet as well. I have had bad GFI outlets right out of the box.
  • Hire an electrician. I would not DIY based on Internet forums.
  • > @zerogravitydrgn said:
    > Hire an electrician. I would not DIY based on Internet forums.

    Where is your sense of adventure? Haha. I agree, hire a competent electrician.
  • > @derotam said:
    There also may have been a general failure of the GFI outlet as well. I have had bad GFI outlets right out of the box.
    >

    I've had very similar damage on GFCI outlets as shown in the video/images provided by the OP from a lightning strike.


    I agree the screw down tabs are as effective as wrapping the wire around the screw and in some cases better because you aren't likely to have part of the wire slip out from under the screw while you are tightening it.
  • Yikes. Glad you're alright. Clearly something about that outlet/wiring was defective.

    Are the screw-down tabs as effective? Seems like wrapping the wire would have almost triple the surface area.
  • > @zerogravitydrgn said:
    > Hire an electrician. I would not DIY based on Internet forums.

    Ditto! Hire an electrician. There's obviously something wrong with the wiring or receptacle installation. Cheap insurance.
  • Did you have an extension cable between the outlet and the charger?

    A lot of chargers have a temperature sensor in the plug and will switch off if the outlet becomes too hot. But if you put an extension cable between the outlet and the charger, you lose that extra bit of safety.

    (A temperature sensing plug will of course not remedy the actual cause for the fire - it will only mitigate the consequences.)
  • Just an educated guess based on a personal experience. But first some questions

    1) Where there additional outlets down-stream of the GFI outlet on that ciruit
    2) If so, was there any load on those outlets.

    If you answered yes to both of those, then it is possible that you were overloading the circuit, but not so much that the breaker tripped. (There are a lot of bad breakers out there).

    Because this is a GFI outlet the entire load goes through it. That causes it to heat, and as it gets warmer the resistance goes up, generating more heat. As you are changing for a long time, things keep getting warming until...

    I had a similar fire in my wife's home office. No EV charging, but a 1500 watt space heater and bad breaker. There was no GFI outlet, but the person who wired the office (I assume it was a previous owner) did not know what he as doing and wired through the outlet rather than using a pigtail.

    Once a again, just an educated guess.
  • OK. I happen to be an electrical engineer who works, when I work with power, with 48V central office battery power. That is: I sure as blazes am not an AC power guy. So, I'm joining the "Call an electrician" brigade. And make sure you call the licensed type, not some joe-blow who might, if you're lucky, be an apprentice electrician.
    Having said that, let's talk about those pictures.
    1. Right-hand most one of five is very positively a NEMA5-15 socket. See https://en.wikipedia.org/wiki/File:NEMA_simplified_pins.svg.
    A real live 20A NEMA5-20 plug has has one blade at right angles to the first; that's not what you've got there. At work, where lots of high-power test equipment is common, we do have NEMA5-20 sockets, which are rigged to take NEMA5-15 or NEMA5-20 plugs.
    2. Standard practice in a garage (I know, my house was built to code, and, for fun, I read some of that code) is that the (usually one and only) NEMA5-15 or NEMA5-20 socket is on its own breaker. If it's a NEMA5-20 (which yours isn't) then it'll be connected to a 20A breaker. If it's a NEMA5-15 (which yours is) then it should be connected to a 15A breaker.
    3. #2 brings up a point: The breaker, the wire gauge from the breaker panel to the socket, and the socket should all match in terms of current carrying capacity. That's a safety issue. One doesn't run a wire gauge that can only handle 10A when you've got a 15A load; you do _not_ want the wires in the wall catching on fire. Now, it might have been that when your house was built, the electrician doing the work decided (depending upon local code and all) that a 20A breaker and wire were the cat's meow and may have even put in a NEMA5-20. That later, for whatever reason, was changed to that GFCI that, clearly, can only handle 15A. In which case.. Trouble. Just check it, will ya? The breaker that turns that socket on and off should have a clear, "15" on it.
    4. Now, sockets do die.
    4a. I, personally, watched a fairly ancient NEMA5-15 socket physically break when I plugged a power cable into it. Sparks flew and the breaker downstairs saved the building from Evil. Plastic doesn't last forever.
    4b. A part time job of mine is fooling with lightning surges and the hardware associated with handling same. Mind you, professionally, I can tell you more than you would like about 48V DC systems and how they handle that kind of thing; for AC, you'll need an expert. Having said that: There's not a whole lot electronic in ye typical non-GFCI socket, so (at a guess) up to a kilovolt transient from a lightning strike down the block won't throw sparks and cause arcing. GFCI sockets have electronics in there to detect when massive currents are flowing in the GND wire. (Normal NEMA5-15 has neutral on one blade, hot on the other, and the load current flows between the two. GND is supposed to be safety ground: that is, if hot gets onto GND (say, an electric hand drill with a metal case that just got dropped into a bucket of water), then a normal NEMA5-15 will probably just blow the breaker, if one is lucky, and blow _you_ if one is not; but with a GFCI, hot and neutral get disconnected by a relay. Which is why one finds these things in bathrooms and kitchens where there's water nearby.) But, that's electronics that does that; one or a couple kV coupled in from a nearby lightning strike can blow those electronics; and, if something fails short, what you're seeing is completely believable.
    I don't think I agree with those who favor screw terminals over push terminals. If push-terminals were that much of a hazard, the UL and standards bodies everywhere would be all over that and would outlaw them. See: Aluminum wiring. It took a little bit, but they got there. Just maybe if the socket was loosely screwed down so that plugging things in or out made it flex like mad.. But that's GFCI. It's a big block, it's hard to make it flex. I think.
    Another point. As it happens, it's NEC standard that one is not supposed to draw more than 80% of a socket/wire/breaker current rating under steady load. The Tesla Mobile Connector (TMC), the NEMA5-15 adapter, and the car enforce this, which is why you get a maximum of 12A, not 15A, when plugged into a NEMA5-15 socket. Further, if the TMC or car developed some kind of fault and shorted out, the very most likely thing that would happen would be for the breaker to pop.
    In conclusion: Probably a surge of some kind, or just a really old socket, did this by wrecking the socket. Highly unlikely to be the Tesla. Things Catching on Fire are Not Normal; bring out an electrican, seriously, and get their opinion. Remotely possible it was the car or the TMC.
  • Thank you all very much, I will call an electrician.
    ps. GFI is required in CA garages so I am going to keep it.
    Addressing the questions and in case it can benefit others:
    @mrburke and @Tronguy the outlet is not on a dedicated circuit / breaker.
    @AllanO the charger was plugged directly to the outlet.
    The charge setup was capped at 12A.
    Like said, I have been charging there for a while. Over the past weeks the GFI fuse started tripping.

    Thank you everyone again.
  • @JLCC: OK. So. Your garage socket is _not_ on its own breaker. As I said, I'm not an electrician or somebody who's intimately familiar with the local and NEC code. But that fact of yours strikes me as somewhat odd. Say you've got your Tesla plugged in and charging away at 12A, which, given the lowish power of it all, it's going to be doing for quite some time. In the meantime, seeing as the hedge outside your house is looking ratty, you snag your hedge trimmer, let's say it's an 8A load, and go to town.
    8A + 12A = 20A, so the 15A breaker goes, "Pop!" Or you're cleaning out the car using a canister vacuum cleaner, 5A load, and, same, "pop!" deal.
    I dunno. Generally, I'm not a fan of a breaker doing its thing; it's asking a, "save your life!" function to save your life. Being the bloody-minded sort (everything fails eventually, including breakers) I dislike saving my life on a function that might break; but if that's code in your area, well, somebody with better smarts than me on the topic came up with the code, so far be it from me to argue.
    FWIW, I've got a TWC in my garage on its own dedicated 60A breaker; doing that gets rid of any funny business about how much current is flowing in a shared breaker.
    Finally: Some years back I hired the Master Electrician neighbor across the street to do the electrical wiring for a kitchen renovation. He promptly assigned me the job of idiot helper and I made it a point to do whatever he told me, no backtalk. (Comments about getting what you paid for allowed.)
    But he did talk about the circuits and such while he was upgrading a 60's-built house to the code that was in force during the reno. And that's when I found out that major appliances like garbage disposals, refrigerators, stoves, and microwaves are each _required_ to be on their own circuit. So, when moving into this new place, it didn't seem like much of a surprise that the one and only duplex NEMA5-15 outlet in the garage was on its own breaker.
    Guess CA is different.
  • AZ is the same way. My 1980 built house had one GFI outlet that had three outdoor outlets and two bathroom outlets downstream of it. At that time, GFI outlets were expensive but were required on exterior and bathroom outlets. Really confused me when the outdoor outlet went out, and I couldn’t figure out why (we never used the bathroom outlets, so didn’t notice they were out too). Took me weeks to figure it out.
  • @JLCC so as Tronguy and others mentioned, you are probably overloading the circuit somehow and caused a heat buildup in that GFI. There are really a couple things you can do... Figure out ALL the other outlets that are on that circuit so you can figure out what those loads are and then either not use them, or adjust your charging to compensate, or get a dedicated outlet installed just for charging your car. In your OP you referenced a 20A outlet you had bought to install, but remember that 20A doesn't really mean anything if the wiring is only rated for 15A. Yes the new outlet won't overheat as fast, but the previous outlet was the weak link and now something else may be the weak link and could cause a fire in a different location.

    Even lowering your charging to 10A may not be sufficient again because of the wire size. On a 15A circuit you are only supposed to pull a max of 12A. You could lower it more as I stated above but you HAVE to know that entire circuit inside and out. It doesn't sound like slower charging is that much of a problem for you, but you have already had one fire, do you want to risk another?
  • Calling an electrician is the right thing to do. Most of the money for an electrician is for him to walk through the door so as long as you have him there have him put in a 240V line. I'd take the opportunity to have him install a Tesla Wall Connector, use a 240V/60A line so that you can run it at 48A. As a reference point I paid $750 for a new 240V/60A and the installation of my Tesla Wall Connector. If you want the flexibility of a socket you won't be able to run an EVSE at 48A but even 32A is fine.

    A point of clarification, you used the words new house and fuse in the same paragraph. If the house is new then you have breakers, fuses haven't been legal for decades. If you really meant fuse then you'll need to replace your panel at the very least, it's a matter of life or death. Your electrician will tell you what you need to do. If you do need to replace the panel as a point of reference when I got my first EV and had my electrician install a 240V/40A line and a ClipperCreek I had to replace my panel, it cost me $2800 to replace the panel and upgrade my service to 200A and a further $375 to run the 240V line. My old panel was from the 50s or 60s, my electrician had been telling me to replace it since the early 90s, his son who is now running the business said that if that panel was in his house he wouldn't be able to sleep at night.
  • GFI's should ONLY be used for outdoor applications or near water sources (i.e. near sinks in garages, kitchens, bathrooms, tubs, etc), but NOT for normal plugs in normal situations.
  • Thank you all again. I am contacting electricians now.
    I may also opt to go with the Wall Connector.
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