Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Tesla wall connector vs NEMA 14-50

Tobin

Member
Jun 6, 2020
44
3
Texas
Why a M3 can draw different amounts of current using Tesla wall connector (48 amp) vs. NEMA 14-50 (32 amp)? Is it some component(s) on the car that decides this current value?
 

Sophias_dad

Supporting Member
Supporting Member
Jul 29, 2018
1,491
1,511
Massachusetts
Its the UMC itself that is the limiter. I presume someone decided that 18 feet of 48 amp capable wiring would be too bulky or unbending and went a size or two down. Either that, or the big ass relays in the UMC got too big or too hot when they needed to handle 48 amps.

Gen1 UMC's could do 40 amps btw, and there's a new version of the UMC that is also 40 amp capable that does NOT have swappable pigtails(Its only 14-50)... Corded Mobile Connector
 

MLXXXp

Member
Apr 27, 2021
49
54
Toronto, Canada
It's because a NEMA 14-50 plug can be on either a 50 amp or 40 amp circuit breaker. (The 14-50 for my electric stove has a 40 amp.) Since there's no way the UMC can determine whether you have a 40 or 50 amp breaker, it limits the current by assuming a 40 amp.

For the wall connector, you program it to match the current capability of the circuit you run it on.

(You can further limit the current with a setting in the car itself.)
 

jdcollins5

Member
Aug 14, 2018
778
510
Wilmington, NC
The standard UMC Gen 2 (shipped with the car) is limited to 32A, 80% continuous on 40A circuit. The plug in adapter connection is part of the limitation.

They sell a High Power UMC Gen 2 that is rated at 40A, 80% of 50A circuit. The 14-50 adapter is hard-wired to the UMC, removing the plug-in connection limitation.
 
  • Like
Reactions: Gasaraki

Rocky_H

Well-Known Member
Feb 19, 2015
6,661
7,957
Boise, ID
Gen1 UMC's could do 40 amps btw, and there's a new version of the UMC that is also 40 amp capable that does NOT have swappable pigtails(Its only 14-50)... Corded Mobile Connector
And that's not new, by the way. The Corded Mobile Connector with that fixed attached plug was sold for quite a while alongside the Gen1 UMC long before they made the Model 3 and made the Gen2 UMC.

But yes, as far as where limits are, it's a lowest common denominator thing, where each piece of equipment can have a limit. The Gen2 mobile charging cord that comes with the car will only allow up to 32A max. The wall connectors can handle 48A max. And as @mrau mentioned, depending on the model of car, it may have a 32A onboard charger for the smaller battery cars, or the 48A charger included in the bigger battery cars.
 
  • Like
Reactions: hcdavis3 and mrau

hcdavis3

HCD3
Supporting Member
Mar 3, 2019
2,272
1,412
02571
And that's not new, by the way. The Corded Mobile Connector with that fixed attached plug was sold for quite a while alongside the Gen1 UMC long before they made the Model 3 and made the Gen2 UMC.

But yes, as far as where limits are, it's a lowest common denominator thing, where each piece of equipment can have a limit. The Gen2 mobile charging cord that comes with the car will only allow up to 32A max. The wall connectors can handle 48A max. And as @mrau mentioned, depending on the model of car, it may have a 32A onboard charger for the smaller battery cars, or the 48A charger included in the bigger battery cars.
Rocky, are you considering getting a new Tesla At some point? Just curious.
 

Jeremy3292

Gas Is Slow
Jul 7, 2021
418
346
South Carolina

I found this article interesting. Thinking of going with the wall connector myself now
 

vikejriw

OD 07/16|MYLR|White/Black/Gemini|No tow|Seattle, W
Jul 18, 2021
17
7
redmond,wa
So maybe someone can tell me if this makes sense, between a wall charger vs a 14-50 plug:
Wall charger - $500 + $40 parts
Nema plug - $35 adaptor+ 220 parts (GFCI breaker, nema 14-50 plug of industrial strength, wires, box) + $35 wall holder (optional I know)

With 30% tax credit the wall charger is : ~$380
The nema plug is ~290

Doesn't it make sense to go for the wall charger then.
 
  • Like
Reactions: hcdavis3

holeydonut

Supporting Member
Supporting Member
Jun 27, 2020
2,125
1,508
East Bay NorCal
So maybe someone can tell me if this makes sense, between a wall charger vs a 14-50 plug:
Wall charger - $500 + $40 parts
Nema plug - $35 adaptor+ 220 parts (GFCI breaker, nema 14-50 plug of industrial strength, wires, box) + $35 wall holder (optional I know)

With 30% tax credit the wall charger is : ~$380
The nema plug is ~290

Doesn't it make sense to go for the wall charger then.



But it looks so badass and can help manage load-shedding with Powerwalls. That's like worth infniity-bucks.
 

hcdavis3

HCD3
Supporting Member
Mar 3, 2019
2,272
1,412
02571
So maybe someone can tell me if this makes sense, between a wall charger vs a 14-50 plug:
Wall charger - $500 + $40 parts
Nema plug - $35 adaptor+ 220 parts (GFCI breaker, nema 14-50 plug of industrial strength, wires, box) + $35 wall holder (optional I know)

With 30% tax credit the wall charger is : ~$380
The nema plug is ~290

Doesn't it make sense to go for the wall charger then.
Plus you get faster charging speed with the wall charger.
 

mrau

Authorized Driver
Supporting Member
Nov 12, 2018
442
840
Mid-Michigan
The 14-50 adapter for UMC has been $45 instead of $35. I think that certainly tips it in favor of the Wall Connector.

Also, you can keep your UMC kit neatly stored in your car at all times. One less thing to pack when traveling.
 

snikt

Member
May 14, 2021
252
362
Denver, CO
I opted for the NEMA 14-50 since it was cheaper and more universal. I just use the UMC that came with the car and didn't have to purchase the $500 wall connector.

Charging speed is more than enough, I actually dial the amperage down a bit too to reduce load
 

Zacster

Member
Sep 11, 2017
212
105
NYC
My understanding, mostly from reading here, is that when using a 14-50 outlet you should not be plugging in and out from it. They are meant for semi-permanent connections, like a dryer that never gets unplugged until getting a new one. In practical Tesla usage then it limits you with using your UMC for on the road as it should just stay plugged in, and getting a second UMC will cost you $300. Personally I wouldn't want to be messing with a high power plug on a regular basis in any case.
 
  • Like
Reactions: mrau and Jeremy3292

Jeremy3292

Gas Is Slow
Jul 7, 2021
418
346
South Carolina
If you already have a spare 14-50 or 14-30 outlet in your garage then just using that is a no brainer. My argument has always been if you are starting from scratch, it makes more sense to just get the wall connector. Plus see article below about 14-50 vs wall connector:

 
  • Like
Reactions: Rocky_H and Zacster

vikejriw

OD 07/16|MYLR|White/Black/Gemini|No tow|Seattle, W
Jul 18, 2021
17
7
redmond,wa
If you already have a spare 14-50 or 14-30 outlet in your garage then just using that is a no brainer. My argument has always been if you are starting from scratch, it makes more sense to just get the wall connector. Plus see article below about 14-50 vs wall connector:

This sounds pretty good advice to me. I am also considering reading the IRS code for if 14-50 can be considered tax rebateable expense for EV Charging Infra (Alternative Fuels Data Center: Alternative Fuel Infrastructure Tax Credit) :)
That might change my math above to make the plug install slightly cheaper (30% off to 300*.7 = $210)
 

Jeremy3292

Gas Is Slow
Jul 7, 2021
418
346
South Carolina
This sounds pretty good advice to me. I am also considering reading the IRS code for if 14-50 can be considered tax rebateable expense for EV Charging Infra (Alternative Fuels Data Center: Alternative Fuel Infrastructure Tax Credit) :)
That might change my math above to make the plug install slightly cheaper (30% off to 300*.7 = $210)
This is directly from the IRS website:

Qualified alternative fuel vehicle refueling property is any property (other than a building or its structural components) used for either of the following:
  • To store or dispense an alternative fuel (defined below) other than electricity into the fuel tank of a motor vehicle propelled by the fuel, but only if the storage or dispensing is at the point where the fuel is delivered into that tank.
  • To recharge an electric vehicle, but only if the recharging property is located at the point where the vehicle is recharged.
In addition, the following requirements must be met to qualify for the credit.
  • You placed the refueling property in service during your tax year.
  • The original use of the property began with you.
  • The property isn’t used predominantly outside the United States.
  • If the property isn’t business/investment use property, the property must be installed on property used as your main home.
It sounds like to me a 14-50 outlet counts but I'm not a tax expert. I got a quote locally here in SC to install the Wall Connector for $1,175. Includes wall connector, 60 amp breaker, wiring, and conduit. So 30% of that I will probably be collecting as a refund on my tax return for 2021 (still looking for other quotes also).
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top