mrau
Authorized Driver
This is an easy fix. Adjust your HPWC to 50 amp and swap out your breaker to 50 amp.
This will increase your Home/EV safety and get a huge Thumbs-Up from all your friends here at TMC.
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Anyone use this Romex 6/3 cable during install?
- Thread starter Dugdale
- Start date
This is an easy fix. Adjust your HPWC to 50 amp and swap out your breaker to 50 amp.
This will increase your Home/EV safety and get a huge Thumbs-Up from all your friends here at TMC.
mstatkus
Member
I ran about 6ft of Romex 6/3 w/ ground. I had only wished I used 1" conduit vs 3/4". It was a tight fit but got it done.
Jeremy3292
Active Member
It is cheaper to run 6 gauge THHN/THWN wires for the 2 hot connections and a 10 gauge THHN/THWN for the neutral/ground wire. It is also safer depending on who you ask but the cost alone should make people do it. Lots of discussion whether or not the 55 max amp of 6/3 ROMEX can be used on a 60 amp breaker or not also per NEMA standards. Easier to just use the THHN wire
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TBrownTX
Active Member
I did 4/3 ROMEX w/ a 60A breaker just to be on the safe side, as it’s an in wall installation.
Tim
Jeremy3292
Active Member
4/3 ROMEX is absolutely acceptable. 6/3 is debatable due to it’s 55 amp limit.
There shouldn't be discussion/debate. It's not acceptable.
Jeremy3292
Active Member
You quoted only pieces of my post which doesn’t show what I actually said. I very clearly stated I would use 6 gauge THHN wires or 4/3 or 4/2 ROMEX. I’m not a certified electrician nor do I know the nuances of electrical law so I will not make absolute statements regarding things that I am not educated on. I merely stated it’s better and also cheaper to buy the single THHN wires so there is no doubt. I’m not going to tell people who are asking for electrical advice on the internet what to do since the only reason to ask is to save money…everyone knows get a licensed electrician or accept the associated risks of a potentially improper install.
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I know, and you didn't make any declarations on it, and I'm not accusing you of something. There's no problem there at all. I was just highlighting two people who have mentioned that this gets debated and discussed much more than it should, because the answer is clear. And over the years, I have taken the time to educate myself on this particular topic so I can make that absolute statement.
Yes, and that gets brought up over and over, because people keep misunderstanding what that means over and over, and I keep explaining it in this forum for years.
They see that description, and it goes like this:
1. "You're allowed to round up the breaker to 60A." (TRUE)
[massive jump to conclusion]
2. "Oh! That must mean a magic wand has been waved that makes it actually BECOME a full 60A rated circuit!" (NO--UTTERLY FALSE)
That's where people mess this up CONSTANTLY! The circuit rating has to fall to the lowest common denominator rating of all pieces of equipment all throughout the chain of that circuit. And no matter how much people want it to be different, the 6/3 Romex is only rated to 55A, and wishing can't make it higher than that, so it can never actually BE a 60A circuit.
So you could for kicks and giggles put a 60A breaker on one end and then....do what? You can't put a 60A rated device or appliance on the other end. So it just sits there with a breaker on one end and open bare wires with nothing connected on the other end. That's useless. So you can only use a device that would be up to 55A, because of the wire limitation. So you effectively have to just use it as a 50A circuit, because that's the highest level where you can get a car charging EVSE and a breaker that both comply.
TLDR: People quote the "round up" thing, but THAT DOESN'T MAKE IT AN ACTUAL 60A CIRCUIT.
mstatkus
Member
Per Manual -
I've seen similar since there is no 55A breaker. i.e. 240.4(B) Rounding up
Looks like this has been re-lived a few times too 60A Breaker -> 4 gage or 6 gage wire?
- If installing for maximum power, use minimum 6 AWG, 90° C-rated copper wire for conductors.
I've seen similar since there is no 55A breaker. i.e. 240.4(B) Rounding up
Looks like this has been re-lived a few times too 60A Breaker -> 4 gage or 6 gage wire?
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Jeremy3292
Active Member
Thanks for the good points. As a follow up thought, I think the 6/3 ROMEX is rated at 55 amps at 60*C and I think the Tesla Wall Connector manual requires it to be rated at 90*C. So that would be another no vote for 6/3 ROMEX.
Edit: just saw @mstatkus post above. Definitely requires 90*C.
Yes, and there is more tricky detail to that too. Both THHN wire in conduit and the wires inside Romex NM-B cable are conductors that are 90' C rated. But again, various other factors. Because of being close together and inside the rubber sheath in Romex, the whole apparatus has to use a 60' C rating, even though the actual wires inside are 90' C type if they were separate. But even more than that, the lugs inside the wall connector and any kind of residential circuit breakers aren't 90' C rated. They are generally 75' C at most. So again, with the lowest common denominator. That's why people have to use the 75 ' C column when using THHN wire in conduit.
The manual has that statement about "minimum", and either of these would comply with that wording about the "conductors" specifically, but everyone also needs to comply with NEC for the overall installation.
mstatkus
Member
Ideas I played around with:
- How many miles do I really need overnight?
- Am I going to keep the Model Y when the Cybertruck comes? i.e. will I do a 2nd charger or just manually share?
- Is battery density/larger battery pack on Cybertruck going to mean I'll want that max 48A charge?
I agree with 99% of everything you post on these forums, and unless manufacturing of NM cables has changed in the last 5 years, the actual letter of the law (NEC) treats the individual conductors inside NM cable with no rating. They are unrated and have no status in the NEC. If you strip back the outer sheath of the NM cable, you see blank insulated wires. Nothing stamped or written on the insulation. They are not considered THHN or any other rated insulation type. You are not permitted to apply any rating to these conductors as individual cables---the Code requires you to consider these as NM cable ends at 60 degree C ampacity, and you cannot strip back more than just enough to terminate them at a wiring device or perform a splice.
Having said that, If you took a sample of the insulation of the inside conductors comprising the NM to a lab to have them analyzed, you would most likely find that they are exactly the same composition as THHN insulation. Probably. Or it could be a lesser, cheaper derivative.
EDIT: Rather than delete my post, I looked up the most recent NEC and found 334.112 which requires NM cable to be constructed with individual conductors rated at 90degree C, so I am wrong above about the conductors having no rating and you are absolutely correct. NM still needs to be rated at 60 degree C, however, and you and I are both in solid agreement on that one.
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That looks like a great site for cable, if the shipping doesn't kill me. Since I want to pull it above the garage drywall ceiling, and I might be the one cutting into the ceiling again in the future, MC seems like the way to go. However, I haven't been able to find a similar site for the connectors on the ends. I'm hoping to feed into the back of the Wall Connector. To minimize wire bend, I'm also wondering if a 45 degree connector would be wiser than a 90 degree connector. Does anyone have suggestions on what connector to use, and where to get it if using that 6/2 Copper MC Cable w/ Ground?
Pluturi
Member
I got all of my materials from these guys, including the cable and connectors, which given your location may make sense. If shipping is high you can consider a higher price/ft from these guys vs. the online lower price...depends on the distance you need to run.
Tightly bending the 6/2 MC is difficult, so you might want to consider any tight bends in the last mile into the wall connector by stripping the MC and running the conductors in conduit with the 90 degree bends. That's what I did.
One example of a connector...
Tightly bending the 6/2 MC is difficult, so you might want to consider any tight bends in the last mile into the wall connector by stripping the MC and running the conductors in conduit with the 90 degree bends. That's what I did.
One example of a connector...
Crouse-Hinds 736DC 1/2 in Flexible Metallic Conduit 90 Degree Connector Zinc Die Cast
Yes, #6 MC is rated for 65A which exceeds the required rating 6pA for a 48A draw EVSE on a 60A breaker.
TomServo
Active Member
Regarding the 6 vs 4 gauge wire along with the 48 amp vs something lower issue on the INPUT side of a WC, however looking at and handling the cord from the WC to the plug on the OUTPUT side of a WC, it seems so thin and pliable even when cold. Does anyone know the size of the wires inside the cord's rubber sheath?
Midnightsun
Active Member
TBrownTX
Active Member
EVer Hopeful
Active Member
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