NEMA 14-50 Meltdown

[GuyGadois]

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

 

[ucmndd]

That hot leg in the foreground looks like it had some pretty good arcing going on.

Lots of insulation tucked into those lugs... a common cause of this is insulation pinched under the lugs causes a loose connection that eventually arcs/fails in this fashion.

 

[tga]

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.

 

[JPP]

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

...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.

 

[Cosmacelf]

This is the reason why I spent the extra money and bought a Wall Connector. It’s just more robust.

 

[ucmndd]

This is the reason why I spent the extra money and bought a Wall Connector. It’s just more robust.

Pinch some wire insulation in the terminals of the Wall Connector and it will do the same thing. Just sayin'...

That said, you folks have convinced me to go and give my 14-50 its semi-annual exam.

 

[Cosmacelf]

Pinch some wire insulation in the terminals of the Wall Connector and it will do the same thing. Just sayin'...

That said, you folks have convinced me to go and give my 14-50 its semi-annual exam.

Maybe but the wires in my WC are thicker gauge, while I normally only charge at 40A at night, so I’ve got more of a margin. But yeah, I’m going to pop the cover off my WC and inspect those lugs too!

 

[JPoldo]

That said, you folks have convinced me to go and give my 14-50 its semi-annual exam.

Me too on the NEMA 14-50 semi-annual exam. Mine was a self-install using the low cost HD receptacle and the mobile connector is removed only a couple of times per year. Now I'm more concerned about the white plastic cover plate and adapter getting warm, but not hot, after an hour. It's time to confirm tightness of wire lugs both at receptacle and circuit breaker. If you do same, double-check no voltage is present before servicing.

 

[Lasttoy]

I dont understand the adapter picture? The Tesla charger cable shoud plug directly into the out without the adapter. That is not a standard outlet. The entire thing looks weird.
I installed my entire circuit myself. Took a hour.
I got my 14.50 outlet in lock box complete at HD.. I forgot the guage wire, but i couldn't hardly bend it. 4 strand wire is required , red, black, white, green. It looks like the black and red were reversed. You can reverse the white and white, but not red black.
50 amp DOUBLE breaker is required.
Its been charging for 2 years. I never remove my Tesla charge cable. Rain or shine.
This just looks wrong.

 

[mswlogo]

I’m a little confused on what outlet and adapters were used based on the 2nd photo. Perhaps this was an older style for older Model S?

If it was a straight 14-50 to a UMC (gen 2) adapter it should have a temperature sensor in the plug and shutdown long before it got this bad. With your setup I’m not sure what was temperature monitored and not.

I totally agree that anything 40A and over you are better off with a wall connector because UMC is limited in Amps (gen 2 model 3). Not sure limitations on Model S.

Plugs are the weakest link. And at the high currents you are better off without the 14-50 plug. Cars tend to bring dampness and sometimes salt near where they park too. Adding to the stress of an outlet. With new setups this “weakest link” has a temperature monitor because it is vulnerable to failure.

 

[mswlogo]

That hot leg in the foreground looks like it had some pretty good arcing going on.

Lots of insulation tucked into those lugs... a common cause of this is insulation pinched under the lugs causes a loose connection that eventually arcs/fails in this fashion.

You can’t conclude either of those things from that photo. IMHO.

 

[obie_fl]

Guys that second picture is the back of the GEN 1 UMC 14-50 adapter it is fused into the outlet.

One of these:

 

[mswlogo]

Guys that second picture is the back of the GEN 1 UMC 14-50 adapter it is fused into the outlet.

One of these:

And that is most likely what allowed it to get that bad. No temperature monitor.

Get rid of it. Get a Wall Connector or Gen 2 UMC.

 

[tga]

And that is most likely what allowed it to get that bad. No temperature monitor.

Get rid of it. Get a Wall Connector or Gen 2 UMC.

No, the grey face adapters are the replacements with temperature monitors. Tesla recalled the original ones that did not have temperature monitors. The recalled ones had a black face.

And yes, the temp sensor should have tripped.

 

[tga]

4 strand wire is required , red, black, white, green. It looks like the black and red were reversed. You can reverse the white and white, but not red black.

Wrong. There is no polarity on AC - there's no such thing as "reversing" red and black, since there's no positive or negative. Both hots are equal, just 180 degrees out of phase. It doesn't matter which wire goes into the X terminal and which goes into the Y, or which terminal connects to which side of the breaker. Saying you can reverse white and white doesn't make any sense. White is neutral; there's only one - nothing to reverse with.

 

[MP3Mike]

No, the grey face adapters are the replacements with temperature monitors. Tesla recalled the original ones that did not have temperature monitors. The recalled ones had a black face.

They recalled them, but they didn't add a temperature sensor, they just redesigned them so that they didn't melt.

 

[tga]

They recalled them, but they didn't add a temperature sensor, they just redesigned them so that they didn't melt.

Really? I distinctly remember discussions during the recall that the new grey ones had temp sensors. Any evidence one way or the other?

 

[MP3Mike]

Really? I distinctly remember discussions during the recall that the new grey ones had temp sensors. Any evidence one way or the other?

The UMC wasn't designed to support a temperature sensor, so what would it hook to?

The only thing they could have done is put a temperature triggered fuse in it, but it doesn't appear they did that.

 

[tga]

The UMC wasn't designed to support a temperature sensor, so what would it hook to?

The only thing they could have done is put a temperature triggered fuse in it, but it doesn't appear they did that.

Yes, there's no temp signal back to the UMC, but I thought there was a single-use temperature fuse in the new ones that would cut power if the plug overheated. Obviously, that didn't happen here.

 

[mswlogo]

Really? I distinctly remember discussions during the recall that the new grey ones had temp sensors. Any evidence one way or the other?

You’d need something to transmit the temperature. If it has a sensor you’d see a couple small pins. You’ll see those in the UMC gen 2 where it plugs into the converter. Some pins tell it which plug (amps)and some pins tell it temperature. None of those exist in the photo shown.