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Burnt nema 14-50 plug and breaker tripped
- Thread starter gh0001
- Start date
nwdiver
Well-Known Member
eprosenx
Active Member
Wow, I am *so* glad your house did not burn down. +1 for metal receptacle boxes and conduit. We will likely never know if the insulation was not properly stripped or the torque was wrong on the connection or if the receptacle itself was the issue. This might be worth reporting to your local Fire Marshall and/or to the manufacturer.
So I most likely would just run new conductors in the conduit. You already have wire in the conduit you can use as pull wire (if you don’t have a fish tape - heck, at 27 feet you can probably just push it through)... I would just go buy some red and black #6 awg and a #10 ground (green or solid core).
I might consider a slightly larger electrical box while you are at it. That one did not look that deep (#6 is grater wire fill than #8 and is stiffer). I might even consider a new breaker since they are only $10 for the non gfci ones if you had any concerns about the breaker. They are only rated for a handful of fault operations.
Tesla recommends either a Hubbel or a Cooper receptacle of specific part numbers. They have a document on their recommendations for a 14-50. I am on my phone so I don’t have the link handy.
Sadly, your juice box pigtail is damaged. I would contact them and see if they can sell you a replacement or repair it for you. This is why the UMC Gen 2 has thermal sensors in the plug! It will detect this kind of situation.
I am becoming more and more of a fan of hardwired EVSE units. Less failure modes.
nwdiver
Well-Known Member
gilscales
Banned
Leviton 50 Amp Flush Mount Shallow Single Outlet, Black-R10-00279-S00 - The Home Depot
You can see in the remarks of this Eaton brand from Home Depot that it is rated for "General purpose"
There are a few people here who swear that they have been using these without an issue for years (maybe not at the full 40A though?) but as you can see it only takes one failure to convince you to get an "Industrial grade" outlet and Hubbell is considered the best.
You can see in the remarks of this Eaton brand from Home Depot that it is rated for "General purpose"
There are a few people here who swear that they have been using these without an issue for years (maybe not at the full 40A though?) but as you can see it only takes one failure to convince you to get an "Industrial grade" outlet and Hubbell is considered the best.
eprosenx
Active Member
A friend had his Leviton receptacle melt due to an incompetent electrician not stripping the insulation off enough and pinching it in the terminal. He replaced it with another Leviton (since it was what he could get quickly and it was not a failure of the receptacle).
The interesting bit is that bit is that he told me that Leviton changed their design between the first and the second receptacle (maybe only installed a year apart?). So perhaps Leviton has improved?
These things get heavily scrutinized by UL or the rating labs so I find it hard to believe they would be dangerous.
nwdiver
Well-Known Member
Only so many ways to mate metal to metal. It ain't rocket science. Maaaaybe the $80 14-50 is made of plastic with sliiiightly higher thermal resistance; but if it's installed correctly that shouldn't matter.
gilscales
Banned
I’m sure the contacts and lugs are heavier as well but I have not compared them so it’s just my best guess
Also why is it not listed as industrial or heavy duty if it is built the same? Leviton lists theirs as general purpose so just seems like it might be cheaper made us all
nwdiver
Well-Known Member
eprosenx
Active Member
Hah, funny you should mention that!
I literally *just* started a thread to discuss this new Leviton receptacle. I am curious what they changed??? (did they decide something with the old one was insufficient?)
Leviton NEMA 14-50r - Changed model from 279 to 279-S00 - New Design?
I'd get a Wall Connector if you want to get full load (max charging rate) on a 50A Circuit (40A).
Otherwise I'd use the 14-50 Adapter on your UMC which has a temperature sensor in the plug.
You "just" had a weak connection. Prongs not tight or not clean (oxidized), possibly not plugged in all the way. It's a LOT of current.
You said something about never removing it on an earlier post. Sometimes exercising a plug is a GOOD thing because it scraps off some the oxidation. Lot's of times on something like that I'll pull it out and push in half a dozen times to get good contact every so often.
You absolutely have to replace that plug if you decide to keep running it that way. I'd periodically check if it warm if you want to keep running like that after the repair. Again, I would not run that setup in my house.
Otherwise I'd use the 14-50 Adapter on your UMC which has a temperature sensor in the plug.
You "just" had a weak connection. Prongs not tight or not clean (oxidized), possibly not plugged in all the way. It's a LOT of current.
You said something about never removing it on an earlier post. Sometimes exercising a plug is a GOOD thing because it scraps off some the oxidation. Lot's of times on something like that I'll pull it out and push in half a dozen times to get good contact every so often.
You absolutely have to replace that plug if you decide to keep running it that way. I'd periodically check if it warm if you want to keep running like that after the repair. Again, I would not run that setup in my house.
gilscales
Banned
Well you got me, they are now both rated industrial grade so I guess they are both the same?
oh wait, there are a couple differences
Leviton 279 industrial grade $10.45
Comes equipped with heavy-gauge, double-wire copper alloy contacts. To ensure correct and speedy wiring, terminals have ID markings.
Operating Temperature: -40°C to 60°C (140 F)
Line Contacts: Brass Double-Wipe
Built of durable thermoplastic
UL94 V-0 Flammability standards
Combo Phillips/standard blade screw terminals
Hubbell HBL9450R Industrial grade $85.48
One piece design power and ground contacts provide low operating temperatures. (Superior)
Operating Temperatures: Maximum continuous 75°C (167 F); minimum -40°C (Superior)
Contacts: Brass, Ground shunt: Brass, Box terminals: copper (Superior)
Built of Reinforced Thermoplastic Polyester (Superior)
UL94 V-2 Flammability standards (Superior)
Floating “V” bottom contact lugs bundle strands to provide high contact pressure and low operating temperatures. (Superior)
Captive Allen head terminal screws permit high torque and clamping pressure required for larger size conductors. (Superior)
I am pretty sure by now that you believe that these are of the same quality and there is no convincing you, If you have never experienced a problem with the inferior made receptacle then that's fine as many people have not had problems.
I am posting the differences here so that other people reading this can make an informed decision about what is best for them.
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nwdiver
Well-Known Member
Pretty sure that's more marketing than a rating. 'UL' is a rating. 'Industrial' is just marketing. If the terminations are correct 140F is all you'll need. If they're not 200F won't be sufficient. UL requirements exist for a reason. If there was a benefit to resistance to 167F then UL would require resistance to 167F.
.... and even IF spending $70 bought you an outlet that had higher thermal resistance... this is a chain. One stronger link does not make for a better chain...
eprosenx
Active Member
Well you got me, they are now both rated industrial grade so I guess they are both the same?
oh wait, there are a couple differences
Leviton 279 industrial grade $10.45
Comes equipped with heavy-gauge, double-wire copper alloy contacts. To ensure correct and speedy wiring, terminals have ID markings.
Operating Temperature: -40°C to 60°C (140 F)
Line Contacts: Brass Double-Wipe
Built of durable thermoplastic
UL94 V-0 Flammability standards
Combo Phillips/standard blade screw terminals
Hubbell HBL9450R Industrial grade $85.48
One piece design power and ground contacts provide low operating temperatures. (Superior)
Operating Temperatures: Maximum continuous 75°C (167 F); minimum -40°C (Superior)
Contacts: Brass, Ground shunt: Brass, Box terminals: copper
Built of Reinforced Thermoplastic Polyester (Superior)
UL94 V-2 Flammability standards (Superior)
Floating “V” bottom contact lugs bundle strands to provide high contact pressure and low operating temperatures. (Superior)
Captive Allen head terminal screws permit high torque and clamping pressure required for larger size conductors. (Superior)
I am pretty sure by now that you believe that these are of the same quality and there is no convincing you, If you have never experienced a problem with the inferior made receptacle then that's fine as many people have not had problems.
I am posting the differences here so that other people reading this can make an informed decision about what is best for them.
Great data! Thanks!
Do you have a picture of the Hubbell you can post? I was not able to load one of the files you posted.
I should buy one of each and take a bunch of pictures perhaps and analyze them in person myself.
I don’t know how to decide what to recommend to folks. It does not seem to me we have sufficient evidence to condem the Leviton receptacles as insufficient. A couple of the failures I have seen were due to pinched insulation. One or two others were indeterminate.
If it was a 3x cost difference at these prices I would recommend the Hubbell all day long. But an 8x price difference for a functionally equivalent device makes me pause.
In many installs the difference is in the noise, but if you are doing an install next to a panel that is a larger cost component.
gilscales
Banned
I did find some I was able to copy, I'm not saying that we should condemn the Leviton but really there is no comparison of build quality and the higher temperature and flammability ratings alone should be worth the extra price, 8X more seems ridiculously more but when you say it is $70 more for a much higher quality outlet after buying a $60,000 car does that $70 really matter? Just the heavy duty Allen lugs and the copper V box lugs are so much better than the Leviton plus you have the added benefit of higher temp rating, one pc. contacts that are far heavier duty than the double wire type in the Leviton, $70 more, thats all? It's a bargain!
I am a General Contractor, All I do is flip houses for a living, I don't work on any places but my own as that keeps me busy, I go deep in the remodels and fix everything that cannot be seen (at least that I can find), I care about my projects and complete them as if I were going to move in myself, we put far more into our places than our competitors and we have to sell our places for more because of that, The last few places we have done since April (when we got our car) we have been including in the garage a 14-50 run on 6/3 Romex with a Hubbell outlet in a 4" metal box with metal cover plate. (so far only one of the buyers had an EV and it was the Fiat, I think that will change soon with all the model 3's I see around here!)
I just ordered another Hubbell but it will be up to 2 weeks before it arrives, I ordered the newest Leviton 279-S00 as well, will take a few close up pics and post when they are both here.
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eprosenx
Active Member
#8 copper in conduit (like THHN wire) can be used at the 75c insulation rating which for #8 AWG copper is 50 amps. So as long as you don't have to derate it for other reasons (ambient temperature or number of current carrying conductors in a raceway), it is allowed by the NEC.
Ampacity Charts - CerroWire
Now it is right at the NEC limit (and in most of my installs I still use #6awg) but I need to point out that it is code legal. Generally the NEC is quite conservative already.
gilscales
Banned
Unless this is the weakest link in the chain, we all know the old sayin "A chain is only as strong as it's weakest link"
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