# NEMA 14-50 meltdown and repair



## bwilson4web

I wanted to charge at lunch but no joy:








The left 'hot' socket had melted.

Here is the failed socket:








Speculation but it looks like the 'hot' wire was the heat source. It then melted the plug socket leading to the failure.

Using a Dremel tool, I cleaned up the plug pin:









I tested it at 32 A, 7 kWh, and there was no finger indication of a hot spot. But I plan to use an IR thermometer to check it after dark.

Here is the replacement, $10:









Questions? Comments?

Bob Wilson


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## iChris93

I can’t see the photos.


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## JasonF

You know I'm going to say stop buying low quality 14-50 outlets!

Either way, from the location of the melting, it looks like the conductor was not screwed down tightly enough and it spent every minute arcing. What I would do is make sure the screw on the new one is tightened down _really_ good, and then wait a few thermal cycles (a few days of charging) and then turn off the breaker and re-tighten the screws again. By then you should have taken up enough slack against the conductor to keep it from arcing.

FYI, I had to go and register for a whole other forum to see the photos.


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## bwilson4web

My apologies about the images. My primary laptop failed and the replacement has yet to arrive. So I'm using an old MacBook.

About the NEMA 14-50, I provided the EVSE, a JuiceBox 40 Pro, but the business has their own 'handy man' who does their electrical work. It wasn't my installation but I manage the EVSE:

7:00 AM to 11:00 PM - keeps the parasites from staying overnight
8 kWh limit - enough to cover a 1-2 hour shopping event
40 A limit - built into the unit but I may reduce the current to avoid another heat event
Free charging at Propst, Pratt Ave, Huntsville, AL
Bob Wilson


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## MelindaV

the typical 14-50 receptical is intended to have an appliance plugged in and left plugged in for 10 years. They are not designed to take regular plugging in and out, and if they do, the internal connection(s) will pull loose and eventually short out.


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## garsh

iChris93 said:


> I can't see the photos.


To see them, I had to create an account at InsideEVs forum.
Then, right-click on each broken photo and "open in a new tab".


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## garsh

MelindaV said:


> the typical 14-50 receptical is intended to have an appliance plugged in and left plugged in for 10 years. They are not designed to take regular plugging in and out, and if they do, the internal connection(s) will pull loose and eventually short out.


NEMA 14-50 outlets are also commonly used for RVs, where plugging/unplugging is common.
The UCHEN outlet that failed on Bob appears to be an "Industrial Grade" outlet specifically intended for RV use.


This failure is probably due to poor clamping of a wire to the receptacle.


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## bwilson4web

MelindaV said:


> the typical 14-50 receptical is intended to have an appliance plugged in and left plugged in for 10 years. They are not designed to take regular plugging in and out, and if they do, the internal connection(s) will pull loose and eventually short out.


The EVSE was plugged in since 2016 in a locked external box. It was the one part I could not check due to the lock.

Bob Wilson


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## Dblbull

I've only used Hubble Industrial Grade 14-50R. Like previous posts have described, A residential 14-50R is meant to be an appliance plug, as these are usually plugged in and left to be plugged in for years. Whereas EV's that may be plugged in and unplugged many times require an industrial plug like Hubble brand. Most cheap residential brands will have a bolt screwing down onto a wire which twists into the strands of the wire as it tightens, thus cutting & braking the strands as you tighten, and when strands break the wire becomes loose and creates heat by arcing between the wire and contact. Hubble brand uses a clamping force to secure the wires. Each clamp should then be tightened to a specified torque, found in the instructions for the receptacle.


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## Feathermerchant

I have NEMA 6-50'sin my installation. I could not find any with the foot on the end of the screw. I observed that if I just strip the conductor and clamp it in the screw, the strands separate and some do not stay under the screw. That can cause heating. So I use some big pliers to twist the strands very tightly together. The twist rate is probably close to double what comes from the factory. When I put the wire under the screw and tighten it down, no strands separate so it should be a better connection. I have not torture tested it lately but AFAIK it stays not too hot at the 40A rating. I now charge at 20A cause that's all I need so I'm pretty sure it's staying cool. A ferrule would be a better solution.


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## Long Ranger

The Hubbell 14-50 is definitely high quality, but I know a lot of folks go with Bryant for about half the price. The Bryant is high quality with clamping terminals and is made by Hubbell.
https://www.zoro.com/bryant-recepta...single-outlet-14-50r-black-9450fr/i/G4438388/


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## $ Trillion Musk

Long Ranger said:


> The Hubbell 14-50 is definitely high quality, but I know a lot of folks go with Bryant for about half the price. The Bryant is high quality with clamping terminals and is made by Hubbell.
> https://www.zoro.com/bryant-recepta...single-outlet-14-50r-black-9450fr/i/G4438388/


Thanks for sharing!

Replaced my Home Depot NEMA 14-50 with Bryant from Zoro, best price out there. Quality is very good. Easier DIY project than expected when using a cordless drill for the hex socket. Make sure to get a matching cover plate.


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## Jim H

bwilson4web said:


> My apologies about the images. My primary laptop failed and the replacement has yet to arrive. So I'm using an old MacBook.
> 
> About the NEMA 14-50, I provided the EVSE, a JuiceBox 40 Pro, but the business has their own 'handy man' who does their electrical work. It wasn't my installation but I manage the EVSE:
> 
> 7:00 AM to 11:00 PM - keeps the parasites from staying overnight
> 8 kWh limit - enough to cover a 1-2 hour shopping event
> 40 A limit - built into the unit but I may reduce the current to avoid another heat event
> Free charging at Propst, Pratt Ave, Huntsville, AL
> Bob Wilson


I used a cheap NEMA 14-50 (leviton) at home running off my 30amp unused dryer plug. Even with only running 24amp thru this plug, the cheap one failed from over heat after 2 years. Replaced with Hubbell and no heat issues after 1 year.
I manage an EV charging area at a resort. We have a Tesla, Siemens, and a NEMA 14-50. I specified the Hubbell for that installation, sure more money, but a much better, safer product.
I learned not to go cheap with charging equipment.


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## Ed Woodrick

Jim H said:


> I used a cheap NEMA 14-50 (leviton) at home running off my 30amp unused dryer plug. Even with only running 24amp thru this plug, the cheap one failed from over heat after 2 years. Replaced with Hubbell and no heat issues after 1 year.
> I manage an EV charging area at a resort. We have a Tesla, Siemens, and a NEMA 14-50. I specified the Hubbell for that installation, sure more money, but a much better, safer product.
> I leaned not to go cheap with charging equipment.


Why not just get the 30A adapter from Tesla?


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## Jim H

Ed Woodrick said:


> Why not just get the 30A adapter from Tesla?


My 30amp plug was in the laundry room. On the other side of the wall was my garage. I had to run a line from the 30amp plug to the garage to a new receptacle. I chose the NEMA 14-50 to utilize what the car came with. I do have a 30amp adapter I travel with. 6-50 adapter as well since my son has a welder outlet at his home.


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## Feathermerchant

Jim H said:


> My 30amp plug was in the laundry room. On the other side of the wall was my garage. I had to run a line from the 30amp plug to the garage to a new receptacle. I chose the NEMA 14-50 to utilize what the car came with. I do have a 30amp adapter I travel with. 6-50 adapter as well since my son has a welder outlet at his home.


So you put a 50A receptacle on the same circuit as a 30A receptacle? Not right and not safe. The 30A and 50A must be on their own circuit. Even drawing 30A from a 30A receptacle when charging your car is not allowed because the car charging load must be limited to 80% of the breaker rating (80% of 30A is 24A).
You are risking a fire with your setup.


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## JasonF

Feathermerchant said:


> So you put a 50A receptacle on the same circuit as a 30A receptacle? Not right and not safe. The 30A and 50A must be on their own circuit. Even drawing 30A from a 30A receptacle when charging your car is not allowed because the car charging load must be limited to 80% of the breaker rating (80% of 30A is 24A).
> You are risking a fire with your setup.


That's not _necessarily_ true. If the circuit breaker is 30 amps, and the wiring is sized appropriately for 30 amps, the only thing they are risking is tripping the breaker by charging the car above 30 amps. Circuit breakers protect the wiring, they don't care what plug you attach to the other end.

It is, however, not quite code to have an improperly rated outlet because it's confusing to the end user. Which doesn't matter as long as you're living there, but if you try and sell the place later it might fail you on inspection.


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## garsh

Feathermerchant said:


> So you put a 50A receptacle on the same circuit as a 30A receptacle? Not right and not safe.


Probably not to code, anyhow.

If the 30A outlet is truly unused, then the outlet itself could be removed and the electrical box that houses it turned into a junction box.


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## Ed Woodrick

Feathermerchant said:


> So you put a 50A receptacle on the same circuit as a 30A receptacle? Not right and not safe. The 30A and 50A must be on their own circuit. Even drawing 30A from a 30A receptacle when charging your car is not allowed because the car charging load must be limited to 80% of the breaker rating (80% of 30A is 24A).
> You are risking a fire with your setup.


And it just about happened. It doesn't take much for a socket that is melting to melt the remainder of the house.


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## Jim H

Feathermerchant said:


> So you put a 50A receptacle on the same circuit as a 30A receptacle? Not right and not safe. The 30A and 50A must be on their own circuit. Even drawing 30A from a 30A receptacle when charging your car is not allowed because the car charging load must be limited to 80% of the breaker rating (80% of 30A is 24A).
> You are risking a fire with your setup.


As I noted in my first response to this thread, I am only running 24 amps thru this 50amp receptacle, that is from a 30amp line. 80% of 30 is 24amps. 
24amps give's me 21mph charge rate and that works fine for me for an home charging system. 
Have been using this setup for 3 years, works great. No fire risk with this setup. Running 24 amps thru a 50 amp Hubbell receptacle works just fine. The cheaper Leviton NEMA 14-50 overheated with the 24 amps I ran thru that, and that was where this tread started.
Yes not to code, but only due to using a higher rated receptacle than what it is being used for. If I used a 30amp receptacle with my correct wiring, then meets code. 
No melting house yet. Receptacle stays cool, wiring stays cool, I'm cool! Az is starting to cool off also. Everything is cool. Tesla's are cool!


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## Ed Woodrick

Jim H said:


> As I noted in my first response to this thread, I am only running 24 amps thru this 50amp receptacle, that is from a 30amp line. 80% of 30 is 24amps.
> 24amps give's me 21mph charge rate and that works fine for me for an home charging system.
> Have been using this setup for 3 years, works great. No fire risk with this setup. Running 24 amps thru a 50 amp Hubbell receptacle works just fine. The cheaper Leviton NEMA 14-50 overheated with the 24 amps I ran thru that, and that was where this tread started.
> Yes not to code, but only due to using a higher rated receptacle than what it is being used for. If I used a 30amp receptacle with my correct wiring, then meets code.
> No melting house yet. Receptacle stays cool, wiring stays cool, I'm cool! Az is starting to cool off also. Everything is cool. Tesla's are cool!


Think what you want, but when a socket melts down, that's a fire hazard. If it stays cool, then how did it melt.

Sure, there are some cheap 14-50 sockets out there. Cheap sockets have caused many fires.


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## Jim H

Ed Woodrick said:


> Think what you want, but when a socket melts down, that's a fire hazard. If it stays cool, then how did it melt.
> 
> Sure, there are some cheap 14-50 sockets out there. Cheap sockets have caused many fires.


Agree when a socket melts down, not a good thing, fire risk. My cheap Leviton overheated, that's why I replaced it. It did not melt, just overheated. 
Hubbell stays cool, no melting there. Hubbell good, Leviton bad.


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