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NEMA 6-50 outlets: Leviton versus Bryant

So I had a pre-existing 40A circuit with a Leviton 6-50 outlet with a 30A EVSE plugged into it for a previous EV. It worked fine with no problems then.

That EVSE was not very reliable for the Model 3, so I put the (then included) mobile connector with 6-50 plug adapter in it. Worked fine for a while...

But during the summer, with warmer garage temperatures, the car sometimes reduced the charge rate from 32A to 16A. The plug adapter on the mobile connector also felt quite warm while charging, although there was no melting or any other indication of damage to it or the outlet. The outlet did not seem to be that hot.

However, I tried replacing the outlet with a Bryant 6-50 outlet (ordered from Grainger, received very quickly) just to make sure it was not the outlet. This did have an unexpected problem with the Bryant 6-50 outlet being too large to fit in the existing box, so a box extension was needed. I also noticed that the Bryant 6-50 outlet has screw-down clamps (similar to the Leviton 6-50), rather than the more mistake-resistant clamping mechanism observed by others with the Hubbell or Bryant 14-50 outlet.

One thing I did notice with a careful look in the prong holes is that the Leviton 6-50 outlet contacts are smaller than those in the Bryant 6-50. This is similar to what a Youtuber has noticed with a Leviton 14-50 outlet, and may be the reason for the heat at the mobile connector's plug adapter.

However, it is still too early to tell if the outlet change fixed the issue, since the weather has not been as warm as it was before.
 

tps5352

Active Member
Supporting Member
…I tried replacing the outlet with a Bryant 6-50 outlet (ordered from Grainger…

I noticed previously that Hubbell/Bryant have more-expensive and less-expensive versions of NEMA 14-50 receptacles. I assume the same is true for their NEMA 6-50 receptacles?

Sounds like you got the beefier commercial version (because of the larger size). But you might want to confirm that using the part number and online parts list from a Hubbell/Bryant websites. (They are one company now, right? But still keep the named products separate.) Their super-good receptacles tend to be expensive—say $75 or more.
 
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Data point: had my Leviton 6-50 outlet melt on me recently. I haven't seen many recommendations for heavier duty 6-50 outlets. Any suggestions?

Note that I was pulling the full 40 amps from a Gen1 UMC. Honestly it seems like 32 amps is just a safer way to go unless you hardwire a wall connector given how hard it is to find a decent 50 amp receptacle. Also, was using a 6 gauge 6-50 extension cord which explains why things melted instead of the UMC derating.
 

tps5352

Active Member
Supporting Member
...Data point: had my Leviton 6-50 outlet melt on me recently...

Yikes! Thanks for those warning photos.

First, I am not an electrician.

However, people (on TMC and elsewhere online) have for years been warning and posting photos about failures of electric-car home charging systems with inexpensive, (mostly NEMA 14-50) retail hardware- and big-box-store 240-volt receptacles.

The impression I've gotten over the years is that it is not so much due to inherent materials per se or even the primary design of the inexpensive receptacles*, but that rather it is often related to the cheap (e.g., flat-blade rather than hex screws) connections. The connectors can and apparently sometimes do come loose more easily with repeated heating/cooling cycles. After so many months/years, you can get arcing and, what you see in your photo. Of course, if installation wasn't adequate (It can be harder to tighten cheap connectors) this can happen even sooner.

And then there is the issue of physical damage from repetitive plugging and unplugging of connectors (not your issue). That could happen with any brand, I suppose. I've been told that most/all 240-volt connectors are not really intended for frequent, repetitive coupling/uncoupling. Comparative examples include the dryer and electric range plugs. Leave them plugged in, I've been advised (analogous to not fussing with inexpensive toilet refill valves).

As I've said elsewhere, I, like so many others, blissfully and ignorantly started off with a Leviton NEMA 14-50 receptacle. After educating myself with TMC posts I found a brand new in-the-box Hubble commercial NEMA 14-50 receptacle locally for sale at a discount on Craig's List (by a licensed electrician) and installed that, instead. Yes a larger cover plate, box, and/or weatherproof cover may be necessary. But the difference in quality is dramatic. With the hex type screws it is much easier to properly torque down the connectors. I think #6-3 (plus ground) ROMEX-type wiring is acceptable for 50-amp circuits, correct? And, of course, a GFI 50-amp breaker. Also, I do charge at just 32-amps at home. Plenty adequate for overnight charging (about 21 mph for the Model X).

So glad your issue wasn't even more serious. If that happened to me, I would be checking my entire circuit (breaker to car), with special attention to any possible loose connection points.
________
* In comparison to standard retail 240-volt outlets the big Hubbell and equivalent Bryant NEMA 14-50 receptacles are monsters. Really well made and so robust. Poor installation could cause one to fail, I suppose, but people who buy Hubbell/Bryant commercial products tend to use pro installation and/or otherwise do things right. I use one of their corresponding NEMA 14-50 plugs. A joy to work with. I assume that their NEMA 6-50 connectors are equally good?
 
True, but the length can matter as the resistance of the wires will increase for longer cables.
However, since the excess heat appears to have been concentrated at the plug and receptacle, it is more likely that the half-contacts in the Leviton receptacle had something to do with it. This may not be due to wearing out, but because the contacts were significantly smaller than the plug blades to begin with.
 
The impression I've gotten over the years is that it is not so much due to inherent materials per se or even the primary design of the inexpensive receptacles*, but that rather it is often related to the cheap (e.g., flat-blade rather than hex screws) connections. The connectors can and apparently sometimes do come loose more easily with repeated heating/cooling cycles. After so many months/years, you can get arcing and, what you see in your photo. Of course, if installation wasn't adequate (It can be harder to tighten cheap connectors) this can happen even sooner.

While the design of the wire attachments of the Bryant 14-50 receptacle makes installation easier and less error-prone, note that the Bryant 6-50 receptacle has screw-down wire attachments similar to the Leviton 6-50 receptacle. So there is no advantage here for the Bryant 6-50 receptacle.

However, the heat that I noticed seemed concentrated at the plug, suggesting that the problem was there. The Leviton 6-50 receptacle contacts were significantly smaller than the plug blades, so the contact area was only about half as large as it could be. That could increase resistance and heat. In addition, the materials in the receptacle contacts appear to be different, which may also have an effect.
 

Big Earl

bnkwupt
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Jul 12, 2017
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16,056
La Conner, WA
View attachment 839488

View attachment 839489

Data point: had my Leviton 6-50 outlet melt on me recently. I haven't seen many recommendations for heavier duty 6-50 outlets. Any suggestions?

Note that I was pulling the full 40 amps from a Gen1 UMC. Honestly it seems like 32 amps is just a safer way to go unless you hardwire a wall connector given how hard it is to find a decent 50 amp receptacle. Also, was using a 6 gauge 6-50 extension cord which explains why things melted instead of the UMC derating.

I'm glad you caught this when you did. Had you let this go much longer, the conductors would have completely melted the plastic that holds them in place and shorted out on the box. I've seen some pretty ugly pictures, particularly when the circuit breaker is bad or slow to respond to the short.
 
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You show the front of the damaged receptacle and the plug. What did the back of the receptacle, especially the connectors, look like, if you don't mind me asking?
I don't have any pictures of the back on-hand but I'll snap some if I can track down the receptacle. There was no visible melting on the backside and the wires were still fully torqued down when I removed them from what I remember (I know that is a common failure mode so I checked).

However, since the excess heat appears to have been concentrated at the plug and receptacle, it is more likely that the half-contacts in the Leviton receptacle had something to do with it. This may not be due to wearing out, but because the contacts were significantly smaller than the plug blades to begin with.
This seems likely to be the issue IMO. Either that, or there was not enough tension on the plug contacts on that side from the get-go.

I'm glad you caught this when you did. Had you let this go much longer, the conductors would have completely melted the plastic that holds them in place and shorted out on the box. I've seen some pretty ugly pictures, particularly when the circuit breaker is bad or slow to respond to the short.
Yea. When I first installed my setup, I checked periodically, but after a few months I got complacent. Glad I noticed when I did.
 
gents: these lighter-weight receptacles are not designed for a long, high amp draw, i.e., charging EV's, which cause them to overheat. For safety, you need the heavy-duty receptacles.
The issue being discussed in this thread is that finding "heavy-duty" 6-50 receptacles is easier said than done. Unlike 14-50 receptacles, there's often not multiple lines of product for 6-50 from the manufacturers and there's no list from Tesla or on the forum.
 
The issue being discussed in this thread is that finding "heavy-duty" 6-50 receptacles is easier said than done. Unlike 14-50 receptacles, there's often not multiple lines of product for 6-50 from the manufacturers and there's no list from Tesla or on the forum.
Pretty easy tbh...just Google Bryant or Hubbell 6-50...

Three online vendors below including Amazon:





The Hubbell version also easy to find:


 
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Big Dog

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Mar 7, 2016
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The issue being discussed in this thread is that finding "heavy-duty" 6-50 receptacles is easier said than done. Unlike 14-50 receptacles, there's often not multiple lines of product for 6-50 from the manufacturers and there's no list from Tesla or on the forum.
Huh? There's this new-fangled thingy called Amazon which delivers next day air.....

Sure, big box stores might not carry HD receptacles, but any electrical supply house that stocks equipment for electricians and contractors would carry them.

The point is don't spend $60k+ on a car and cheap out on the plug.

btw: Tesla would be foolish to publish a "list" as every DIY'er would use it and would blame Tesla for a bad install.
 
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I also noticed that the Bryant 6-50 outlet has screw-down clamps (similar to the Leviton 6-50), rather than the more mistake-resistant clamping mechanism observed by others with the Hubbell or Bryant 14-50 outlet.
The Bryant catalog page at https://hubbellcdn.com/catalogpage/Bryant_Catalog_A27_CatPage.pdf lists only one 6-50R, part number 9650FR.

It lists five 14-50R, part numbers 9450FR, RR450F, RR450FW, RR450, RR450PM. The RR450* ones are listed as "residential grade".

Pretty easy tbh...just Google Bryant or Hubbell 6-50...

I'm guessing the Bryant/Hubbell is better than the Leviton, but see above discussion. It's not completely obvious.

Huh? There's this new-fangled thingy called Amazon which delivers next day air.....

Sure, big box stores might not carry HD receptacles, but any electrical supply house that stocks equipment for electricians and contractors would carry them.

The point is don't spend $60k+ on a car and cheap out on the plug.

btw: Tesla would be foolish to publish a "list" as every DIY'er would use it and would blame Tesla for a bad install.
I thought Tesla previously published a list of recommended 14-50 receptacles. I could be wrong.
EDIT: Tesla instructions on installing a 240 volt outlet do list two example 14-50 part numbers - Examples: Hubbell part # HBL9450A, Cooper part #5754N
 
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