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Rating on 6-50 UMC Gen 2 Adapter is only 30a rated - why?

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
So I am one of the poor souls that ordered my M3 on 4/18 and got the "July pushback" email.

That leaves me with nothing to do but order accessories and hangout on the forums (now that I have completed my wall connector and NEMA 14-50 plug installation).

I have ordered and received four adapters for the UMC gen 2 that I expect to get shortly with the car. Each one has a max current rating on it which makes complete sense (12a for the 6-15, 16a for the 6-20, and 16a for the 5-20), except for the 6-50 adapter. It says it is only rated to 30a! I would have expected it to say 40a (80% of 50) OR 32a since that is the max rating of the UMC.

A friend who already got his Model 3 sent me a picture of the 14-50 and it indeed says 32 amps. So I would have expected the 6-50 to be the same.

Can anyone provide any insight here? Even once I get my car I won't have a 6-50 outlet to plug into (I just ordered that adapter figuring it would be the "safest" to build adapters from since it does not have a neutral pin so it would make the adapters safer by not creating any floating neutral situations) in order to test it.

The Tesla website shows the 14-50 and 6-60 as providing identical range per hour so I would assume it would draw 32 amps in either situation, but VERY odd that this is stamped with a 30a limit. I don't suppose there is any way that could be a typo? (seems virtually impossible to think that someone would make that kind of mistake?)

-Eric
View attachment 307131 View attachment 307130
image2.jpeg
View attachment 307127
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Last edited:

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
Apparently I can't figure out how to drive the forum software. Here is the picture of the 6-50 that is only rated to 30 amps according to this.

IMG_3290.jpg
 

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
Well the forum software seems completely broken... It won't let me upload this picture no matter how small a resolution I compress it to.

Hrm, I just screen-shotted it and am trying to upload the (now huge) .jpg that created, maybe this will work...

Screen Shot 2018-06-05 at 11.34.47 PM.png
 

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
AFAIK all gen 2 UMCs are limited that way.

But this is limited to *30a* not *32a* which is what the UMC Gen 2 is limited to.

I have no idea why this stupid picture won't upload to the forum. I swear to you it says 30a on the 6-50 but 32a on the 14-50 (which makes sense).
 

Zaphod

Galaxy President (former)
Dec 10, 2015
2,160
1,959
Austin, TX
Have your friend come over to your house (if possible) and see what his car charges at using your plug. Possible the printing on the plug is just typo unless there is some legitimate reason. Maybe someone more knowledgeable can chime in. Otherwise, wouldn't hurt to contact Tesla directly and see what they say.
 

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
Have your friend come over to your house (if possible) and see what his car charges at using your plug. Possible the printing on the plug is just typo unless there is some legitimate reason. Maybe someone more knowledgeable can chime in. Otherwise, wouldn't hurt to contact Tesla directly and see what they say.

Yeah, I don't have a wall plug for 6-50 even though I bought the adapter (I put in a 14-50 plus a HPWC). I will try to test at some point if I get a chance and report back!

I was curious if anyone else had seen this or had tested a 6-50 before?
 

Zaphod

Galaxy President (former)
Dec 10, 2015
2,160
1,959
Austin, TX
Yeah, I don't have a wall plug for 6-50 even though I bought the adapter (I put in a 14-50 plus a HPWC). I will try to test at some point if I get a chance and report back!

I was curious if anyone else had seen this or had tested a 6-50 before?
Oh, somehow I took it that you actually had a 6-50 plug, but rereading guess I just jumped to that conclusion on my own. :p

I don't think 6-50 is very common so probably not many people out there with real world experience. Even if it is limited to 30A for some reason, max charge rate you can get (without HPWC) is 32A, so really not much difference. Still kind of odd. Maybe the 6-50 has to be derated 40% instead 20%. EV charging probably is considered continuous high power draw and maybe 6-50 isn't rated for that type of duty cycle. I'm not an electrician so just guessing.
 

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
Oh, somehow I took it that you actually had a 6-50 plug, but rereading guess I just jumped to that conclusion on my own. :p

I don't think 6-50 is very common so probably not many people out there with real world experience. Even if it is limited to 30A for some reason, max charge rate you can get (without HPWC) is 32A, so really not much difference. Still kind of odd. Maybe the 6-50 has to be derated 40% instead 20%. EV charging probably is considered continuous high power draw and maybe 6-50 isn't rated for that type of duty cycle. I'm not an electrician so just guessing.

Yeah, super weird. But Tesla quotes the 14-50 and 6-50 as adding the exact same miles of range per hour, so I would think if there was a two amp difference those numbers might be slightly different? So friggin weird. I wish someone technical from Tesla would respond on these topics...
 

CricTic

Member
Mar 21, 2014
102
97
United States
I have a 6-50 plug attached to a 40A circuit, and currently use a Gen 1 UMC to charge my car at 32A. I have a 6-50 for the Gen 2 UMC on order and it just shipped - so if this question is still unanswered in a week or so, I can test with my car and let you know if it charges at 30A or 32A.
 
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eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
As a side note, I wonder if making the image size smaller would work.

Yeah, that was my first thought. It did not work. Tried progressively smaller images. I also took a screen shot of the original image since it had come from an iPhone and I had converted it from HEIC to JPG and I thought maybe something had broken in the file in the process. No joy, but then it started showing up the next day in one of my posts <shrug>
 

eprosenx

Active Member
May 30, 2018
2,074
2,517
Beaverton, OR
I have a 6-50 plug attached to a 40A circuit, and currently use a Gen 1 UMC to charge my car at 32A. I have a 6-50 for the Gen 2 UMC on order and it just shipped - so if this question is still unanswered in a week or so, I can test with my car and let you know if it charges at 30A or 32A.

Awesome! Thanks! That would be great!

At this rate who knows when my M3 will come and I have no 6-50 plug to test it with. (I am one of the poor souls who ordered on 4/18 and got the "july pushback" email)
 

markb1

Active Member
Feb 17, 2012
3,054
662
San Diego, CA
Yeah, that was my first thought. It did not work. Tried progressively smaller images. I also took a screen shot of the original image since it had come from an iPhone and I had converted it from HEIC to JPG and I thought maybe something had broken in the file in the process. No joy, but then it started showing up the next day in one of my posts <shrug>

The forum seems to be having problems with images, recently. I’ve noticed lots of people having problems.
 

davewill

Active Member
Feb 5, 2014
1,828
1,981
San Diego, CA, US
I suppose the design might have failed testing at 32a and they decided to derate to 30a, but it doesn't seem likely since it is so similar to the 14-50.

It was that kind of thing that caused most J1772 EVSEs to be limited to 30a. The original J1772 midrange plugs made by Yazaki couldn't get certified at 32a, so everyone made 30a EVSEs even though the required 40a circuits could support 32a. It wasn't important at the time (and really isn't now) as the only cars available were the LEAF and Volt, both limited to 16a, anyway.
 
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DR61

Member
Apr 14, 2016
561
619
Gold River, CA
I have a J1772 Levition 40-amp EVSE that is plugged into a 6-50 on a 50-amp breaker, installed by an electrician 4 years ago. I will get the Tesla 6-50 adapter when the Model 3 comes (this summer?) and test the UMC with it. Otherwise I will normally use the Leviton to charge the car.
 
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