A couple of nights ago I heard a loud pop inside our house complete with lights flickering. I went downstairs to the garage and found the garage with smoke and stinking of electrical smell. I noticed the Tesla was not longer charging and the breaker was tripped. Upon further inspection I noticed the outlet and 14-50 adapter were now melted together. We were absolutely lucky the breaker tripped. The charging system was put in over a year ago with no issues. My original 14-50 adapter was replaced by Tesla because they stated there was a chance of starting a fire (that is what I recall the letter said). For my setup I use the 14-50 adapter with the Tesla mobile always plugged into it. I never unplug the mobile charger from the 14-50 plug except for very rare occasions (once or twice a year).
I sent these photos to Tesla Charging and they said that maybe it was caused by not using an industrial strength receptical and that maybe the one used was a Levitron. Unfortunately, I can’t figure out what brand it is since they are fused. I should be able to separate the two. I will have an electrician take a look at this and report back. FYI, Tesla came and pickup the car for inspection even though they said they didn’t see any reports from the car of any problems.
GG
I am so glad you and your family and your house ended up OK. I have a number of thoughts on this (I know this post is old, but it just popped back up)
This is something we have seen quite a few times in the forums. A melted 14-50 receptacle.
It may be impossible to tell now, but my guess is that either a screw terminal was insufficiently torqued down on one of the hots, OR, more likely, insulation was not stripped back far enough and was caught between the screw terminal and the wire.
When current flows over it the receptacle will heat up massively until it melts.
I will note that it looks like 8awg wire to me and while “in conduit” like that 8awg is fully code compliant, it is right at the edge of its rated capacity. Ambient temp can’t be over 86 degrees Fahrenheit in the install location.
Those Leviton receptacles really are cheap. Someone here on the forums bought one of each of all the receptacle types they could find and the quality difference is like night and day. The Hubbell and Bryant and Cooper ones all have clamp terminals while the Leviton one just crushes the wire with a screw. EV charging does really push these things to the max for hours on end and so I think we are finding weaknesses in products that never were discovered since they were previously not pushed that hard.
I should also note that you have a UMC Gen 1 and so you can charge at the full 40a. I am guessing this kind of scenario was one of the major reasons Tesla made the new UMC Gen 2 only 32a capable. It also has the thermal probe in the end of the adapter that communicates to the UMC/Car. I did think the UMC Gen 1 added a basic thermal fuse/disconnect at some point (not electronic).
A question: Was none of those wires green in color for ground? Also, I think technically that may not have been a fully code compliant install since or think the ground was supposed to have been attached (bonded) to the electrical box locally. That may not have had anything to do with the failure or how it was “cleared”, but I do call it out.
FWIW, I probably would use 6 awg replacement wire for the hots and neutral (ground can be as small as 10 awg).
This is exactly why I do a "temp check" every couple of weeks. After a couple of hours of charging (so things can warm up), I manually check the temp of all connections, plugs, etc. The breaker will be noticeably warm (~100F), but not hot - you can hold your hand on it indefinitely. All other plugs, outlets, and connections shouldn't be warm at all.
Doesn't really help the OP, but maybe the next person down the road.
I'm sort of anal about this, and use a torque-limiting screwdriver to make sure everything is tightened to spec. I've never had any heating.
Yeah, I have a thermal camera for this reason.
...maybe you don't want to use the electrician who did the original NEMA 14-50R install....not the best install and a loose connection will lead to this.
As far as the actual NEMA 14-50R you use, if you do not unplug and plug back in your Mobile Connector very often, you can use the 'cheap' $10 receptacle. But if you do a lot of disconnects, then opt for the $80 heavy duty one. Rated for more duty cycles.
So another forum member bought all the different receptacles and took pictures and reviewed them.
I would like to call out that I don’t think insertion cycles is the only metric that differentiates things. The quality of the wire terminals and the temperature at which the plastic of the receptacle melts are also large factors. I personally have become a fan of the Bryant receptacles as they are nearly identical to the Hubbell ones but at a more reasonable price (Zoro.com has them).
This is the reason why I spent the extra money and bought a Wall Connector. It’s just more robust.
Totally agreed. The receptacle is the weakest link. I think the future of EV charging is largely hard wired perhaps. All the dangerous situations I have seen have been with melted receptacles or extension cords.
Wow, the exact same thing just happened to us! Fortunately, my wife went out to get something from her charging M3, and smelled the smoke. I disconnected the cable from her M3, but when she tried to pull the 14-50 adapter from the outlet, it threw off a huge spark. We killed the circuit breaker ( and noted that the breaker for my M3 - which was not plugged in, had already tripped). We called our trusted Electrician (not the ones who installed the original as part of our home builder's subcontractor). Thank God that we were not asleep! The face plate of the 14-50 plug had melted onto the prongs of the adapter.
I am so glad you and your family and your house ended up ok!
So are you positive that your breaker was the one that tripped?
This sounds to me like her receptacle overheated and melted but did not short out and so did not trip the breaker. When she pulled out the receptacle it caused the wires that no longer had any insulation to short from hot to hot, hot to neutral, or hot to ground. This then blew the breaker.
Can you post a bunch of pictures like the original poster? These are all good learning opportunities for everyone here (and folks will find it in the future in google searches).
I am guessing your failure mode was similar to the original posters, though if you both have M3’s then is it reasonable to assume too both have UMC Gen 2 units? Odd that thermal protection did not trip.
