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Tesla Wall Connector amp limit
- Thread starter Gulfbear
- Start date
Yes--6 gauge of any wire or cable type is always sufficient for a 50A circuit.
Yes, as long as it is not Aluminum Romex. As another user kindly pointed out to me, the HPWC does not allow AL conductors (which #6 AL would be undersized as well).
If the electrician set the Wall Charger to 40A, then he did nothing wrong with the 40A breaker... as long as he used the correct wire gauge, minimum 8AWG.
And you pretty much nailed it about "upgrading" to a 50A or 60A breaker. You need to know two things before you consider that:
1) How thick the wire is coming out of the breaker, it needs to be at least 6AWG
2) If your main service panel can handle the extra current of 50A or 60A. To determine that, you or your electrician will need to do a load calculation of your home. Assuming he already did one before adding the 40A, my best guess is that another 10-20A will not be a problem for you.
Actually no, technically per the NEC. That romex(NM-B) is rated to 55 amps because its not 6 gauge in conduit(usually THHN). a 48 amp load from a model 3 would need wiring rated to 60 amps, and a 60 amp breaker, because its considered a continuous load. You should limit that 6AWG romex to a 40 amp breaker. You could probably >try< a 50 amp breaker, but expect nuisance trips as the wires and breaker heat up.
That said, it might work fine with a 50 amp breaker.
Consider using ferrules for the ends of 6AWG. They make much better connections, less likely to overheat.
Yes, definitely, I'd pop the cover off the electrical panel and see which wire is the one that now has a 40 amp breaker on it, or just(literally!) put the car on the charger at 35-40 amps for 10-15 minutes and feel for which wire is getting warm. There would only be like three wires of larger-than-10 gauge coming out of most electrical panels(usually black or gray in color, but not always on older construction), so it should be really easy to find.
And to answer another question along the way, you really don't need 40 amp charging, 32 should be fine virtually all the time.
I would not rush to upgrade. I bet what you have will be plenty fast enough.
Pay attention to what was being asked and don't start off with "Actually no". @Vines is correct. You're disagreeing because you're talking about a 60A circuit and running a 48A load, but that's not what @MaryAnning3 was asking about. She was asking about a 50A circuit, running at a constant 40A load. So yeah, of course a 55A wire rating is sufficient for that. And for Pete's sake, Tesla even specifically recommends 6 gauge wire in their official install documents for the 50A circuits.
One thing I have noticed is that there are quite a few people here with pretty intimate knowledge of electrical. The detail in some of the posts leads me to believe that some responders in this thread are either electricians, General contractors, or otherwise have to work with electrical systems in their "day jobs".
Just saying its nice to see the knowledge etc being shared by you all.
Just saying its nice to see the knowledge etc being shared by you all.
Glad to help, and its fun to learn new* things. (*Like RTFM lol)
I am a designer of PV systems for an electrical contractor, so sizing wires is part of my core skill set. I also want to see EV succeed, and getting black eyes of fire damaged houses when EV charging goes wrong makes the general population hesitant. Charging cars at home on 50A+ breakers is unlike probably any other plug in load at the average residence, and confusion in the trades due to inexperience adds to the problems.
Electrical is very advanced DIY. Its risky like plumbing in the relative danger to your home if things go wrong. You could easily cause tens of thousands of damage to your home if either fails, so be really really really sure before you leap into the DIY of EV charging at home.
Yes, thanks for pointing that out, I was actually coming back to fix it... I was incorrect, the 50 amp breaker is fine for the 6AWG NM-B. That's actually what I have in place right now, with my HPWC set to 40A. At the same time, it is NOT technically okay to use it with the HPWC set to 48A. It is not clear from the poster of the 6AWG question whether they understood the 1.25 adjustment for continuous loading.
eprosenx
Active Member
To clarify (as I am not sure exactly how to read your comment) - we are assuming the electrician used 8 awg romex (NM cable) for that 40a circuit - that is totally fine (6awg would be fine too). The mistake was setting the Wall Connector to allow charging at a 40a rate. It needed to be set to allow charging only at a 32a rate (80% of 40a).
As to the size of the wire if you wanted to upgrade to a 40a or 60a breaker. It is fine to do 8 awg on a 50a breaker if the wire is THHN in conduit (probably it is not in conduit in this situation). 6 awg is good for a 60a breaker if THHN in conduit. If using Romex (NM cable) then you need 6 awg for 50a and 4awg will take you all the way to 70a.
I totally agree on your port #2.
All this discussion on electrical is one reason why I decided to hire one of the "tesla recommended" electricians in my area. I called 2 other electricians (one recommended by my successful real estate agent, one that had dome some work for me around the house before), in addition to the "tesla recommended" one.
The first 2 had never installed a tesla wall connector, but said they could install the NEMA port, and could I please send them over the manual from the wall connector to review before my appointment. After I described my install desires (which are pretty simple), they both quoted me somewhere between 300-500 labor for install.
The tesla recommended one quoted me 400-600, but also told me they would pull permits as required, asked me questions about house size and how many air conditioning units i had, brand of panel, house amp service, etc. The owner of the company happened to answer the phone and said "I think our company has installed about 7000 to 8000 wall connectors in the past few years. The installer I am sending to you has installed over 3000 of them for me".
Its worth the extra money to me to get this done right, by someone who "knows" it. I only know electrical well enough to install a ceiling fan in an existing box, or change an regular outlet, or install a gfci. Anything else, I want a pro. Electricity is no... joke.. and I absolutely want to ensure that its safe first and for most, and then that I can get the charging speed I want.. safely.,
The first 2 had never installed a tesla wall connector, but said they could install the NEMA port, and could I please send them over the manual from the wall connector to review before my appointment. After I described my install desires (which are pretty simple), they both quoted me somewhere between 300-500 labor for install.
The tesla recommended one quoted me 400-600, but also told me they would pull permits as required, asked me questions about house size and how many air conditioning units i had, brand of panel, house amp service, etc. The owner of the company happened to answer the phone and said "I think our company has installed about 7000 to 8000 wall connectors in the past few years. The installer I am sending to you has installed over 3000 of them for me".
Its worth the extra money to me to get this done right, by someone who "knows" it. I only know electrical well enough to install a ceiling fan in an existing box, or change an regular outlet, or install a gfci. Anything else, I want a pro. Electricity is no... joke.. and I absolutely want to ensure that its safe first and for most, and then that I can get the charging speed I want.. safely.,
For the wall charger settings, the manual states the breaker rating as well as the max current (based on 80% of the breaker rating) in a table. I assumed the electrician used the breaker rating when setting it to 40A. Thanks for promoting a clarification.
