Thanks for linking that document. It's nice to see that Tesla does specifically recommend installing a high quality, industrial grade receptacle, specifically the Hubbell and Cooper.
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NEMA 6-50 outlets: Leviton versus Bryant
- Thread starter 3sr+buyer
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Thanks for linking that document. It's nice to see that Tesla does specifically recommend installing a high quality, industrial grade receptacle, specifically the Hubbell and Cooper.
Jeremy3292
Active Member
Leviton is quite possibly the worst brand to use for any receptacle. It feels like a lightweight child's toy vs other brands. The Lowe's brand Utilitech is so much better for a budget receptacle.
For the 6-50 receptacles, the Bryant appears to be better than the Leviton in terms of contact with the plug blades, which should reduce the chance of overheating at the plug that you experienced.
It does not appear to be better at the wire connections, since the Bryant and Leviton use similar screw-down clamps (indeed, the Leviton has bigger screws) for the 6-50 receptacles (unlike for the 14-50 receptacles where at least one Bryant model has a more mistake-resistant wire attachment method).
Right. I hear that back in the day (when Tesla 40-amp Gen 1 mobile home connector equipment [e.g., Tesla UMC and CMC] was the norm) Tesla at first promoted the installation of NEMA 14-50 receptacles (and the $520 Tesla Corded Mobile Connector) on their website. But too many reports of home plug/receptacle failures ensued. (Probably often the result of questionable installation practices by DIY'ers, rather any problem with the Tesla charging equipment per se.) Anyway, more emphasis began to be placed on having licensed professionals install Tesla wall connectors (along with adequate wiring and breakers). (Plus Tesla lowered the maximum charge rate to 32-amps for its Mobile Connector.)
On yeah, there it is. Note how 'dated' the content is. The Gen 1 UMC is still portrayed. (Things change so rapidly in Tesla-world.)
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The Utilitech 6-50 receptacle is this:
Jeremy3292
Active Member
Yea. I also expect to see better "EV-grade" 50 amp receptacles. I can plug a 1500 watt space heater into a 5-15 plug and not worry about whether the receptacle was a "heavy duty" version. Your average 30 or 50 amp outlet is typically used for intermittent loads often well below 50 amps. EV charging stresses these outlets much more and so higher quality receptacles are needed. Although frankly it seems crazy to me that these companies can market their outlet as 50 amp capable when they melt after sustained 40 amp loads.
TBH I didn't notice much difference between the Utilitech 50 amp and the Leviton, although I didn't spend much time comparing them. I used the Ulititech b/c that's what Lowe's had on hand and I needed to charge my car b/c it was sitting at like 4% state of charge and I was leaving the next morning. Hopefully that one lasts longer, although I will be (for unrelated reasons) using this plug for only a fraction of my charge sessions going forward, so unfortunately it won't tell us much.
Do the contacts in the plug holes of the Utilitech receptacle contact the full plug blades, or only part of the plug blades?
Jeremy3292
Active Member
See my post below for in depth pics. Certainly seems much better IMO.
The word "intermittent" is key. Even a space heater cycles on and off. An EV draws continuous full power for hours, building up heat, eventually causing a low-end circuit to fail.
One other thing noticeable about different outlets is that the contacts in the Leviton plug holes look like they are steel, versus brass in most other outlets. Although brass is less conductive than pure copper, steel is likely to be less conductive than brass, according to https://www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials and TIBTECH innovations: Metal properties comparison: electric conductivity, thermal conductivity, density, melting temperature .
So a less conductive material contacting only about half of the plug blades seems like a formula for more resistance and heat compared to a more conductive material contacting the full plug blades.
Seems odd that a receptacle that overheats at the plug interface under 32-40A continuous load could be rated as a 50A receptacle that should be able to handle up to 40A continuous load.
So a less conductive material contacting only about half of the plug blades seems like a formula for more resistance and heat compared to a more conductive material contacting the full plug blades.
Seems odd that a receptacle that overheats at the plug interface under 32-40A continuous load could be rated as a 50A receptacle that should be able to handle up to 40A continuous load.
The contacts in the utilitech (above) look like they contact the full plug blades.
There's definitely something weird going on with the contacts in the Leviton plug (below). It's hard to capture in a picture, but the inside contact is much smaller and, on the melted side, very misaligned. The contact is loose on that side, so I suspect the extremity of the misalignment is due to the melting of the plastic holding it in place.
TLDR, the Leviton NEMA 6-50 outlet seems to have a pretty severe design defect. I would highly recommend against using one of these, regardless of application. After looking at this closely, I'm frankly surprised there hasn't been a recall for this product.
Back looks fine (both photos above are of the melted Leviton plug). I don't think the screw terminals played any part in this failure.
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They also look like they are brass, rather than appearing to be less conductive steel as in the Leviton 6-50 outlet.
So far, no excess heat issues with the new outlet, either from the EVSE lowering the charging rate due to heat, or the feel test (feeling the plug and outlet for heat) while charging.
Since the new outlet has similar screw-down wire contacts as the old, but has full brass plug blade contacts instead of the half steel plug blade contacts of the old, that points to the plug blade contacts as the main problem with the old.
Since the new outlet has similar screw-down wire contacts as the old, but has full brass plug blade contacts instead of the half steel plug blade contacts of the old, that points to the plug blade contacts as the main problem with the old.
Hey! Looking around for that Cooper outlet (I need one that handle Al) and I see a bunch of Eaton outlets, did Eaton buy Cooper and is the quality still worth it? I keep finding Eaton 5754N
RayK
Active Member
I don't want to sound alarmist but if I had a circuit which I was going to strain its capabilities (i.e., continuous high current) that is wired with aluminum, I'd replace the entire length with copper.
This is a pretty perennial debate — the AL is done to code, and is the metal that runs the service line into our house, but I understand people’s misgivings. As far as I can tell, it’s the low quality outlet with bad clamps and no space behind the wires and clamps (in the surface mount style) that cannot dissipate the heat properly.
RayK
Active Member
I understand that service drops are done with Al and when installed to code on branch circuits, are supposed to be safe. However, several years ago the buried line running from the street and between the driveways of me and my neighbor's disintegrated into dust. I don't know the exact reason which caused the failure but I was shocked to see what amounted to powered aluminum inside the shell of insulation.
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