I am waiting for delivery of my MY and have a quick question about home charging. My house was built 4 years ago and it has a NEMA 14-50 receptacle in the garage. I cannot find information about the maximum current for this outlet. Is it safe to charge a MY with this outlet and a NEMA 14-50 adapter?
Welllll...I would have said yes, it's that basic and simple except for your follow-up question. The Model Y will not come with the 14-50 adapter plug included, so you would want to order that from Tesla. It's $35. So if it were a standard normally installed 14-50 on a 50A circuit, that's what you would do. But...
Is it a code violation if you put a NEMA 14-50 receptacle and it is wired to support only 20A draw?
Oh, uh, what? Are you saying you've looked, and it is actually hooked up to 20A two pole breaker? Technically that is not a code violation, but it's usually sloppy bad practice. Code specifies that the breaker must not be higher than the rating of the outlet. So for a 14-50, you are not allowed to use for example a 60A breaker. But someone could put a 20 or 30A breaker on there. There are very few reasons for doing that though.
How are you interpreting this? I've seen several people confused about how the breaker ratings work, where they think you multiply or divide by 2 because of voltage levels between 120V or 240V or one and two pole. What does it look like and what is the actual number printed on it? I'm wondering if it says 40, but you're thinking it like divided in half for some reason, which is not correct.
So here is what would happen if that's what you have. You would plug in the Tesla charging cable with the 14-50 plug, and it will try to pull the max amps that it is built for, which is 32A. And the 20A breaker should trip within a minute or two. So that's just not a good setup. So what can you do about it? Well, that depends on what size of wire you have.
1. If there is thick enough wire in the wall that would support a 40 or 50A circuit, then you could keep the 14-50 outlet and put the right size breaker on it.
2. If the wire is small, like really sized for a 20A circuit, then it shouldn't have that 14-50 outlet on there. Put an appropriate 20A outlet type on there, like a 6-20, and buy the 6-20 adapter plug from Tesla.