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Gen 3 Wall Charger plugged into NEMA 14-50 outlet with 60 amp circuit

focher

Active Member
Oct 15, 2013
1,008
1,446
Bay Area
Personally, I use a 14-50 wall plug on a 40A circuit and then put a 14-50 connector cable on the HW2 I have. Of course I only get 32A but that has been more than enough to support both my Model 3 Performance and my wife's X100D. I think some people tend to over-engineer their charging needs.
 
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F14Scott

Member
Apr 7, 2019
201
328
Houston
Personally, I use a 14-50 wall plug on a 40A circuit and then put a 14-50 connector cable on the HW2 I have. Of course I only get 32A but that has been more than enough to support both my Model 3 Performance and my wife's X100D. I think some people tend to over-engineer their charging needs.
If you have a 14-50 outlet on a 40 Amp breaker, future users who aren't you might plug a 50 Amp thing into it without knowing it is on a 40 Amp breaker. Sure, the breaker would probably trip to save itself in that situation, but that's not a great gamble to be taking. You ought to clearly mark the outlet as being able to accept only 40 Amps of draw.
 

gfunkdave

Member
Aug 10, 2016
121
168
Portland, ME
If you have a 14-50 outlet on a 40 Amp breaker, future users who aren't you might plug a 50 Amp thing into it without knowing it is on a 40 Amp breaker. Sure, the breaker would probably trip to save itself in that situation, but that's not a great gamble to be taking. You ought to clearly mark the outlet as being able to accept only 40 Amps of draw.

I suppose if it's in the garage this might be a concern, but a 14-50 is totally legal on a 40A circuit since there's no such thing as a 14-40 outlet. But this is also probably why Tesla limits the UMC to 32A, and why other level 2 charging manufacturers make both 40A and 32A versions of their chargers.

40A breakers on a 14-50 outlet are very common for electric ranges. My kitchen has such a one, for example.
 

Black306

Member
Oct 14, 2019
519
745
Sacramento
I suppose if it's in the garage this might be a concern, but a 14-50 is totally legal on a 40A circuit since there's no such thing as a 14-40 outlet. But this is also probably why Tesla limits the UMC to 32A, and why other level 2 charging manufacturers make both 40A and 32A versions of their chargers.

40A breakers on a 14-50 outlet are very common for electric ranges. My kitchen has such a one, for example.
Are you sure your range doesn’t have a 14-30? They do look similar at a glance. I find it very unlikely a 14-50 outlet protected with a 40A breaker would be within code in any county/state.

31398E3D-2EFC-4B8D-B419-4966D79FE1A0.jpeg
 
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Rocky_H

Well-Known Member
Feb 19, 2015
6,094
7,056
Boise, ID
Are you sure your range doesn’t have a 14-30? They do look similar at a glance. I find it very unlikely a 14-50 outlet protected with a 40A breaker would be within code in any county/state.
Yes, absolutely certain. This is done a lot, and the NEC has it specifically written in that this is an allowed exception to put 50A types of outlets on 40A rated circuits because of there not being a 40A outlet type. This absolutely is done on ovens all the time, and it IS fully code compliant.

However, it would not hurt to label it in the garage because someone might not know that it's done that way and assume wrongly about it.
 
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miimura

Well-Known Member
Aug 21, 2013
6,155
5,748
Los Altos, CA
Also, if you look at the installation instructions for many plug-in EVSE that deliver 32A to a vehicle, they use a 6-50 or 14-50 plug and indicate a 40A breaker. It would be advisable to use #6 wire instead of #8 copper wire so that the breaker could be upgraded to 50A if necessary for a future application or appliance or 40A EVSE. 40A breaker on a 50A outlet is definitely within code.
 
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