Maybe this is why Tesla discontinued the 6-50 UMC adapter so quickly (I think it was early in 2013), because they were being plugged into outlets that weren't 50A but it would try to draw 50A.
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Another point I can make here is that the HPWC does not require a neutral. If faced with having to pay an electrician to pull a neutral (or a new cable completely), I would consider removing the box and attaching an extension ring with conduit up the wall to connect to an HPWC. In many cases, it'll be less expensive to purchase the HPWC equipment, compared with getting the neutral there.
Installing a HPWC is a great idea. With the new advanced design and lower price it is a great deal. You can keep your UMC in the car, and not have to unplug and stow it when you leave for longer trips.
If your wiring is up to it, you can also upgrade your breaker from 40 A to 50 A. (the two 40's do not mean you can draw 80 A)
You also have the option of upgrading your wiring to 60 A for a 48 A charger, or 90-100 A for a 72 A charger. (EVs are continuous loads, so they only can use 80% of the rating for the wires and circuit breaker)
GSP
If your wiring is up to it, you can also upgrade your breaker from 40 A to 50 A. (the two 40's do not mean you can draw 80 A)
You also have the option of upgrading your wiring to 60 A for a 48 A charger, or 90-100 A for a 72 A charger. (EVs are continuous loads, so they only can use 80% of the rating for the wires and circuit breaker)
GSP
To be fair, quite a few EVSEs come standard with 6-50 plugs. Others come standard with 14-50.
Conceptually, 6-50 makes more sense because EVSEs don't normally need a neutral wire but 14-50 is more generally common because it is used for electric ranges and ovens and at RV parks -- because it has a neutral wire it is usable with a broader array of devices.
A 6-50 inherently limits charging to 80% of 50A or 40A of charging. Most plugin cars are not Teslas and EVSE vendors commonly support 6-50 and/or 14-50 and it's a bit chaotic and confusing. I'm just saying it's completely understandable that a builder might install a 6-50 P outlet for an EVSE.
FlatSix911
Porsche 918 Hybrid
You have a NEMA 6-50 receptacle... just have it replaced with the correct outlet or HPWC as recommended previously on this thread.
Here is a handy guide for reference
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FlatSix911, I know how you like to post graphics, but have you read the above posts? You can't just replace a 6-50 outlet with another one of your choice.
Understandable, yes, but it's the wrong choice, and builders need to be educated that it's the wrong choice. Tesla sells more EVs in the US than the next two manufacturers combined. A 14-50 outlet would be the best choice as it's the recommended one for Teslas, and owners of any other EV could buy an EVSE that plugs into that outlet just as easily as they buy one that plugs into a 6-50. Also Tesla is the only EV that can plug directly into a 240V outlet with a mobile connector-- all other EVs require a J1772 EVSE. A 6-50 outlet requires a Tesla owner to buy a J1772 EVSE he doesn't otherwise need, or else go through one of these contortions with rewiring the outlet or using an adapter as discussed above.
FlatSix911
Porsche 918 Hybrid
Yes, as an engineer, I like the use of graphics to convey a lot of information in a simple format ...
I read the entire thread and would suggest the OP consider a HPWC or new outlet <40A with no Neutral.
If this house was really built with a 6-50 socket and a 40A breaker, the cheapest and easiest DIY solution is to buy a 30A or 32A EVSE that already has a 6-50 plug on it. There are units made by Siemens, Leviton, and Clipper Creek that would be plug and play and totally safe in this situation. The only disadvantage is that you would have to use the Tesla J1772 adapter for daily charging.
Example: Clipper Creek HCS-40P
Example: Clipper Creek HCS-40P
Nice graphic guide, I can get some use out of this.You have a NEMA 6-50 receptacle... just have it replaced with the correct outlet or HPWC as recommended previously on this thread.
Here is a handy guide for reference
View attachment 179600
Perfectly legal. It's legal to connect a 50A receptacle to a 15-amp breaker, provided the load intended to be connected to the 50A receptacle is nameplated at 15A. There is no Code that says a 50A-capable receptacles must be on a 50A breaker.
In fact, many many new homes have 14-50's on a 40A breaker for the range receptacle.
ElectricTundra
P85D AP1
As @FlasherZ said, what they did is fine. What you would not want is that outlet or wiring on an 80a breaker. Generally what is critical is that the breaker rating be less than the wiring or outlet rating (and wire rating should take in to consideration distance and size). Thus the breaker protect things before the current draw exceeds the wire or outlet rating.
FWIW, I'd second the recommendation for a HPWC. You can set it for the charge rate that your wiring and breaker can consistently provide and you can keep your UMC in your car should you need it at some point.
Perfectly legal like you said, but stupid and behind the times IMO especially with millions of EVs on the way. There are some 70,000 homes in one of my neighborhoods with range 14-50s on 8/3+1 Romex on 2-pole 40s just to save the home builders a couple of bucks.
Vr
If you have safely determined that you have 6/2+1 Romex and that it would be a complete hassle to deploy any of the great suggestions by others upthread, I would be (reluctantly) willing to sell one of my spare 6-50s, but you would need to cover the cost of the adapter + the additional $20 I paid in shipping (Tesla only shipped overnight express in '13) and we can make the exchange at Glen Alen.
dhrivnak
Active Member
FlasherZ are you sure? Many NEMA 14-50 circuits will use the neutral to split in not two 120v circuits. If you do not have a neutral the 120v will not work. It is not unsafe it just will not work.
Boatguy
Active Member
Two 40a breakers bridged is a 220v 40a circuit, good for 32a of sustained charging.
The real question is what is the wire connected to those breakers. Circuit breakers protect the wire (and your house from burning down).
Do you have a 40a, 48a, 72a or 80a charger in your car?
#6 copper wire will support a 50a circuit to drive a 40a charger on a 50' one way wire run from the panel. 48a would need #4 wire. It's all about the installed wire size, what's at the ends can be adjusted as needed.
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