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NEMA 14-50 Plug Meltdown / Near Fire

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The Model 3 UMC-2 knows what type of outlet you're plugged into and sets the current automatically to 80% of the 80% rating of the 14-50 outlet. 50 X .8=40 X .8=32. You can't set it higher. You can set it lower. If the UMC-2 senses a high temperature, it will ramp down current automatically and may display one red bar at the top.
This is true if you have the correct adapter on the charger. I could plug a 14-50 into a 16AWG wired outlet and the Tesla will pull amps until the wires melt or the CB trips.
BUT!...
It doesn't sense high temperature in your house wiring or the circuit breaker. It won't ramp down if you're drawing more current than the outlet is rated for.

EDIT: Here are the adapters you should buy for your installed circuit.
Gen 2 NEMA Adapters
 
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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!
I'd ask electrician or inspector to verify installation under load with FLIR camera or equivalent . See Got a Flir camera to check for electrical safety - Pictures! for examples.
 
I'd ask electrician or inspector to verify installation under load with FLIR camera or equivalent . See Got a Flir camera to check for electrical safety - Pictures! for examples.

I was going to suggest this also. We shoot all new installations and all existing once per year. I think it would be a good standard practice for electricians. A quality Flir camera is not cheap but not so much to be unreasonable for a professional to have. For home owners and DIY'ers there are a few inexpensive ones that connect to a smart phone. I have never used one so I do not know how well they work. you can also carefully run your hands over the cord plug and j-box to see if they are warm.
 
ANY device which uses close to a circuit’s limit, should be thoroughly checked under load.

Preferably have over size cable and undersized circuit breaker, and never pull the full rated load for the particular circuit without a very thorough check.
Cable which is hidden away and out of site could be the failure point, especially over time as the heat will build up.
It’s the weakest link in the chain- and any slightly high resistance point will potentially heat up till a fire results.

I know what mine will safely support at home, (Yes, oversize cable from the switchboard) and use it accordingly, but whenever I use an unknown power outlet I reduce the charge current to be 100% safe.
 
ANY device which uses close to a circuit’s limit, should be thoroughly checked under load.

Preferably have over size cable and undersized circuit breaker, and never pull the full rated load for the particular circuit without a very thorough check.
Cable which is hidden away and out of site could be the failure point, especially over time as the heat will build up.
It’s the weakest link in the chain- and any slightly high resistance point will potentially heat up till a fire results.

I know what mine will safely support at home, (Yes, oversize cable from the switchboard) and use it accordingly, but whenever I use an unknown power outlet I reduce the charge current to be 100% safe.

Any thing that is expected to operation continuously for 3-hours or more should be treated as a continuous load and cannot be rated more than 80% of the branch circuit rating. That is way a 50 amp feed to a wall connector will only charge at 40 amps, 60 at 48, etc. Electricians should know that but most electrical devises don't fall into that criteria so it could get overlooked.

Having said that, a standard 50 amp circuit, without any above-and-beyond oversize wire, should have been plenty over sized for a UMC which is limited to 32 amps. It would only be loaded to 64%. Eprosenx may have it right that a cheap receptacle may be to blame. Unfortunately, this is what Home Depot sells and therefore what most people have easy access to.
 
I had a similar experience with a 14-50 receptacle in our new house. The receptacle was wired with aluminum wiring, unfortunately, and the electrician not only didn't torque the terminals down properly, but he also failed to use anti oxidant on the aluminum. After having the receptacle replaced, and the charging cable (as the connector on the charging cable also melted some), I checked the torque on the terminals myself to make sure the connector was proper, and that it had anti oxidant. But, also, to avoid it heating too much again, I also dialed the charging current down some, so the charging takes a little longer, but haven't had any more problems with it.
 
Our city requires a city inspector to check and approve electrical installations such as these. Assuming this is the case in other cities, it would be worth noting to them the issues that have been reported with certain receptacle models, such as the Leviton.
 
I have read all these post and 1 CRITICAL point is missing. Any circuit can only support a max of 75% of rated capacity. This means that your dedicated 50 Amp circuit should not be loaded with more than 37.5 amps. The Car must be set to draw no more than that. I have a 30 amp circuit so my Model 3 is set to draw 22 amps. If I set the Car to draw 30 amps then overheating of wires will occur. This fact is not clearly elaborated on anywhere.

This is incorrect. You are probably thinking about the 125% / 80% rule (that you have to oversize by 125% for continuous loads which results in only being able to use 80% of the installed circuit capacity). There is no 75% rule.

Even at that, the circuit is rated for the full amount. The reason for the derate for continuous loads is that if you run continuous current for a long time it will heat up the breaker and it may blow inadvertently. (known as a nuisance trip)

So for your examples: A 50 amp circuit is good for 40a. A 30a circuit for 24 amps.
 
"Your point" is giving people a false sense of security. Having a licensed electrician doesn't make you safe. Period...dot. My pictures above are proof of that.
Your comparison to seat-belts is not applicable at all to this.

I’m giving people false sense of security?

By telling people to follow proper guidelines and make intelligent decisions? lol

I never stated that doing what I said will be 100% safe and nothing will happen - that would be a false sense of security.

The average person has a much greater chance of NOT burning the house down by following my advice. It’s simple logic
 
"Your point" is giving people a false sense of security. Having a licensed electrician doesn't make you safe. Period...dot. My pictures above are proof of that.
Your comparison to seat-belts is not applicable at all to this.

+1

It's up to the individual. If you don't feel comfortable... hire someone. If you want to learn and DIY... learn and DIY. There are plenty of resources available to ensure you do it correctly. Just do your homework. All this DIY-shaming is kinda silly.

This was also installed by a licensed electrician. They're not magic...

Screen Shot 2019-06-11 at 12.41.51 AM.png
 
I’m giving people false sense of security?

By telling people to follow proper guidelines and make intelligent decisions? lol

I never stated that doing what I said will be 100% safe and nothing will happen - that would be a false sense of security.

The average person has a much greater chance of NOT burning the house down by following my advice. It’s simple logic
In my experience AND from reading threads like these, I've seen the average homeowner can do a better job than a qualified electrician. It's my opinion. Not a single wire in my garage has melted, yet, a licensed electrician DID NOT install it and a county inspector DID NOT inspect it. What you said in your original post suggests that I shouldn't be alive right now. I always agreed that a licensed electrician should do the work and you should get it permitted. But have someone else come and look at it, or like someone else suggested, get a thermal camera to look at it. Super easy to do but nobody wants to drop $3k on a camera.

My goal here isn't to save $500. (I bought a $100k car) My goal was to do it safe! If you want to trust your family's life in the hands of a single stranger with piece of paper (license), that's your prerogative. I started this conversation with you because I've seen failed outlets and fires time and time again. What you originally said absolutely gives a false sense of security. I don't care about homeowners insurance, I care that it's done right. If it's done right, your house won't burn down.

The majority of these failures (if not all) in this thread are from qualified installers! I'm glad no one was injured at least.
 
My goal here isn't to save $500. (I bought a $100k car) My goal was to do it safe! If you want to trust your family's life in the hands of a single stranger with piece of paper (license), that's your prerogative. I started this conversation with you because I've seen failed outlets and fires time and time again. What you originally said absolutely gives a false sense of security. I don't care about homeowners insurance, I care that it's done right. If it's done right, your house won't burn down.

Thank you! Keep fighting the good fight here. A license in itself doesn't make someone an expert or force him or her to do a proper job. And an electrical inspector generally isn't going to rip open a breaker panel or or outlet.
 
A related issue is the amount of heat generated during charging at home with a Tesla home charge unit. When I ordered our 2015 Model S 85 D, the wall-mount was offered as an option and so I purchased it along with the car. I arrived about three weeks before the auto was delivered and I had a licensed electrician do the install. It was connected to a 100 amp service with breaker arrangement. The unit itself was then set for 100 amp charging which the car backs down to 80% automatically, so 80 amps.

I have found that at times to handle on the output end of the cable is too hot to touch comfortably, so I pull out my handkerchief to unplug, if the car is still charging or has just completed. Over the past few months I have noted that the black composite cowling around the plug is cracking, beginning on the sides and now running from both sides to the middle front.

Has anyone else had this issue arise?
wallmount plug 2.jpg
Wallmount plug 1.jpg
 
A related issue is the amount of heat generated during charging at home with a Tesla home charge unit. When I ordered our 2015 Model S 85 D, the wall-mount was offered as an option and so I purchased it along with the car. I arrived about three weeks before the auto was delivered and I had a licensed electrician do the install. It was connected to a 100 amp service with breaker arrangement. The unit itself was then set for 100 amp charging which the car backs down to 80% automatically, so 80 amps.

I have found that at times to handle on the output end of the cable is too hot to touch comfortably, so I pull out my handkerchief to unplug, if the car is still charging or has just completed. Over the past few months I have noted that the black composite cowling around the plug is cracking, beginning on the sides and now running from both sides to the middle front.

Has anyone else had this issue arise? View attachment 418021 View attachment 418019

This is a serious issue. Contact Tesla immediately for assistance. You need that unit (or its cord or the charge port on your car) replaced.

Hot is *not* ok.
 
I read this thread last night and contacted my electrician if he can avoid using leviton parts for my NEMA 14-50 outlet install later this month. He mentioned he can use vista parts instead.

My terrible Googling did not come back with any results regarding vista quality, does anyone know how vista electrical parts fare against leviton?
 
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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!
I found a similar thing when I replaced my double wall oven last year. Outlet was totally charred. Totally could have caught the house on Fire. Eeks!
 
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.View attachment 417002

One question I would have, is was the connection wire aluminum (say AWG #6) or was it copper (say, AWG #8)? ***CORRECTION*** just looked at the pics and it looks like he used #6 Copper which should easily handle 40 amperes. Copper is much more tolerant than aluminum for loose connections and therefore I'd strongly suggest at least part of the problem was that horrible GEN 1 nema 14-50p adapter, since the connection pins on it heat UNACCEPTABLY on all of them at 40 amperes.

The problem with an Aluminum wire and Leviton combination is that Leviton's cheesey screw terminals in lieu of box lugs is that it is difficult to remain TIGHT. If I was forced to use such junk I'd retighten the connection after a few days to make sure the aluminum wire was tight in the connection - and of course as with all Aluminum Terminations to clean the wire (to get rid of Al-Oxlde film, a non-conductor), with emery cloth, and then put some kind of no-ox (Oxy-Ban, etc.) on the connection to keep the air and water out.

The old 40 amp original Tesla convenience cord had multiple problems - 40 amperes through the Nema 14-50P adapter where the juice went through 2 microscopic connection points was just asking for trouble - as Tesla themselves realized by eventually doing the following:

1). Monitoring the 'droop' and decreasing the current by 80% in stages until the 'droop' was deemed acceptable. This was overly cautious in places with distant wiring or stingy utility policies, yet it did prevent fires due to droop at the poor connection Tesla adapter. I couldn't believe the heat coming out of one at a model S at the Mississauga (Toronto) Service Center, of all places.

1a). (The fact that the 'portable EVSE' itself only used a 30 ampere rated relay with 40 amperes going through it explains why many of the 'mini S-shaped' evse's melted and needed to be replaced).

2). Putting a 'fuse wire' in later adapters so that the juice will shut off prior to a fire.

3). Bringing out NEW 32 ampere (model 3 style) travelling cords that have the adapter some distance AWAY from the wall outlet... The lower current and less heat at the wall outlet has just got to make things much safer.
 
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