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6/2 romex, Gen 3 WC help

NJM313

New Member
Mar 13, 2022
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2
NJ
Hello, I am hoping to get some advice on wiring setup for a gen 3 WC. I am getting a lot of conflicting info including speaking with licensed electricians. I am planning to install a 3rd gen WC. Originally I was planning on using 6/2 romex, on a 60amp breaker to get the max 48 amps. Now I am reading that this is no good because of continuous load.

So assuming thats correct, my options are:

-Use #6 THHN wire in conduit
-Install the 6/2 on a 50amp breaker and charge at 40 amps
-Use 4/2 romex which doesnt seem to be available

This sound right? For my application I have to go through a wall or two, so would I need to install conduit through the wall if I went with THHN? If I go with the 6/2 on a 50amp route, do I need to use conduit in the portion of my garage where the wire is exposed?
 

qdeathstar

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May 17, 2019
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Hello, I am hoping to get some advice on wiring setup for a gen 3 WC. I am getting a lot of conflicting info including speaking with licensed electricians. I am planning to install a 3rd gen WC. Originally I was planning on using 6/2 romex, on a 60amp breaker to get the max 48 amps. Now I am reading that this is no good because of continuous load.

So assuming thats correct, my options are:

-Use #6 THHN wire in conduit
-Install the 6/2 on a 50amp breaker and charge at 40 amps
-Use 4/2 romex which doesnt seem to be available

This sound right? For my application I have to go through a wall or two, so would I need to install conduit through the wall if I went with THHN? If I go with the 6/2 on a 50amp route, do I need to use conduit in the portion of my garage where the wire is exposed?

Take some pictures of your panel and route to the location. But in general you will want to run #6 thhn in conduit (can be flexible conduit if it makes running it easier) if you want to run it at 48 amps. Or you could just run NM cable and charge at 40 amps. Personally unless the conduit run is super simple I don’t see the advantage of charging at a faster rate…. Your car will be parked most of the time while you are there anyway, plenty of time to charge.

The romex will have to be protected from physical damage the entire length of the run. So conduit would work in the garage to protect it from damage. You can only run NM in a conduit if the location where the conduit is installed is considered a dry location per NEC.
 
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NJM313

New Member
Mar 13, 2022
3
2
NJ
Take some pictures of your panel and route to the location. But in general you will want to run #6 thhn in conduit (can be flexible conduit if it makes running it easier) if you want to run it at 48 amps. Or you could just run NM cable and charge at 40 amps. Personally unless the conduit run is super simple I don’t see the advantage of charging at a faster rate…. Your car will be parked most of the time while you are there anyway, plenty of time to charge.

The romex will have to be protected from physical damage the entire length of the run. So conduit would work in the garage to protect it from damage. You can only run NM in a conduit if the location where the conduit is installed is considered a dry location per NEC.
Thanks for the reply. It’s not a difficult run for conduit but it is a little long at 60’. I will have to run the conduit in the garage for the romex either way. I think I’ll just go the romex route on the 50amp breaker I guess.
 
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-Use #6 THHN wire in conduit
Correct with a 10 gauge THHN ground wire. This is the best option.
-Install the 6/2 on a 50amp breaker and charge at 40 amps
This is a possibility but may not be allowed per local code in a lot of places and isn't worth the hassle IMO. The user configurable software is a hazard as you (or someone else) can easily change the software later to 60 amps and now your breaker and wiring isn't up to code. ROMEX is generally not recommended for a wall connector install; it is used more on 240v outlet installs.
-Use 4/2 romex which doesnt seem to be available
Yes, but it is overkill and not cost effective.
This sound right? For my application I have to go through a wall or two, so would I need to install conduit through the wall if I went with THHN? If I go with the 6/2 on a 50amp route, do I need to use conduit in the portion of my garage where the wire is exposed?
I'm not certain about how it works through walls, but @Rocky_H may have some thoughts.
 
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Rocky_H

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Feb 19, 2015
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ROMEX is generally not recommended for a wall connector install; it is used more on 240v outlet installs.
Huh? That doesn't make sense. You can use whatever it is that meets the amp rating requirement of the circuit, regardless of whether the device to be attached on the end is an outlet or a wall mounted device. Romex or not doesn't matter. If it's a wall connector on a 20 or 30 or 40A circuit, there are certainly gauges or Romex that are fine for that. The choice of whether to use wires in conduit or Romex is about where the wire needs to run. Some places can use Romex, but some need conduit.

I'm not certain about how it works through walls, but @Rocky_H may have some thoughts.
If it's just "in" a wall, that's generally what Romex is for, but I'm not sure what that description of "through" a wall means. If it's external on one side and then needs to go all the way through a wall to be external on the other side, I'm not sure what that should use, so I won't necessarily weigh in on that. If Romex is in a wall and then needs to come out and go along the surface, it is allowed to do that in conduit for a little distance.
 
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Huh? That doesn't make sense. You can use whatever it is that meets the amp rating requirement of the circuit, regardless of whether the device to be attached on the end is an outlet or a wall mounted device. Romex or not doesn't matter. If it's a wall connector on a 20 or 30 or 40A circuit, there are certainly gauges or Romex that are fine for that. The choice of whether to use wires in conduit or Romex is about where the wire needs to run. Some places can use Romex, but some need conduit.
Lots of local and state codes don't allow the software configured wall connector to be dialed down, it must be configured for max power aka 60 amps. The only ROMEX suitable for that is 4/2 ROMEX, which was not widely available even pre-pandemic/inflation. Tesla also recommends using individual THHN wires. So yeah I'm with you in theory that you can use "whatever it is that meets the amp rating requirement of the circuit" but in the case of the wall connector ROMEX is "generally not recommended" for all the reasons I previously listed (notice I did not say it couldn't be used).
 
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Rocky_H

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Feb 19, 2015
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Lots of local and state codes don't allow the software configured wall connector to be dialed down, it must be configured for max power aka 60 amps.
That is simply wrong. Code would not state that at all. Some inspectors might say something like that, which is simply incompetence. I would fight that tooth and nail to get them to give a correct answer, or appeal that to another inspector until they get a clue.
Tesla also recommends using individual THHN wires.
No.
So yeah I'm with you in theory that you can use "whatever it is that meets the amp rating requirement of the circuit" but in the case of the wall connector ROMEX is "generally not recommended" for all the reasons I previously listed (notice I did not say it couldn't be used).
It's the national electric code for installing an appliance---not a "theory".
 
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That is simply wrong. Code would not state that at all. Some inspectors might say something like that, which is simply incompetence. I would fight that tooth and nail to get them to give a correct answer, or appeal that to another inspector until they get a clue.
Local and state codes would absolutely state something like this. The NEC may not but local and state codes vary from the NEC; most states and localities do not simply adopt the NEC "as is" without modifications. It is also very unsafe to install a circuit that could be later configured by another user in a way that violates the current wiring and breaker size. It is also literally states to check local codes if installing for less than maximum power in the Tesla wall connector manual:

1647286602498.png

You are mistaken. Tesla's wall connector installation video clearly shows THHN wire being used. That is why I said very clearly ROMEX is "generally not recommended" but I did not state it couldn't be used. For your reference here it is: Click Here
It's the national electric code for installing an appliance---not a "theory".
Now you are just arguing semantics of my wording. It is very clear what I was saying.
 
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Rocky_H

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Feb 19, 2015
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Local and state codes would absolutely state something like this. The NEC may not but local and state codes vary from the NEC; most states and localities do not simply adopt the NEC "as is" without modifications.
Ah, I forgot that there are a very few places that have ridiculous requirements. Chicago is notorious for that. They require conduit for absolutely everything. You're right there.
It is also very unsafe to install a circuit that could be later configured by another user in a way that violates the current wiring and breaker size.
But it is definitely NOT doing that. You put in the correct wire size that goes with the correct breaker size. Done. That is not unsafe.

It is also literally states to check local codes if installing for less than maximum power in the Tesla wall connector manual:
All right, yes, the Chicago thing to get people to buy more conduit.
You are mistaken. Tesla's wall connector installation video clearly shows THHN wire being used.
Now that is ridiculous. Several things are allowed by code to done multiple ways. If Tesla picks one to use as an example in their video, that does not mean that they are specifically recommending against all other ones. It's allowed to use orange or blue or purple or some other colors of hot wire instead of red. If Tesla used orange wire in their example video, you are saying right here that it means they are recommending "against" using red because it wasn't what they used in their example. That just does not follow logically at all.
Now you are just arguing semantics of my wording. It is very clear what I was saying.
No, it's very important to distinguish that something is specific in following code, not just someone's opinion or theory.
 
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qdeathstar

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Local and state codes would absolutely state something like this.

Which local code?

It is also very unsafe to install a circuit that could be later configured by another user in a way that violates the current wiring and breaker size

It is perfectly acceptable to install an outlet that has a higher rating that it’s over current protection device. Eg a 20 amp receptacle can be installed on a 15 amp circuit. The over current protection insures that more than the acceptable amount of current won’t be used, not the device. If someone set the charge to 48 amps but it was installed on a 20 amp breaker the breaker would trip.

You are mistaken. Tesla's wall connector installation video clearly shows THHN wire being used. That is why I said very clearly ROMEX is "generally not recommended" but I did not state it couldn't be used. For your reference here it is: Click Here

So, if the video showed Romex you would be arguing that Romex was prefered?
 
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Now that is ridiculous. Several things are allowed by code to done multiple ways. If Tesla picks one to use as an example in their video, that does not mean that they are specifically recommending against all other ones. It's allowed to use orange or blue or purple or some other colors of hot wire instead of red. If Tesla used orange wire in their example video, you are saying right here that it means they are recommending "against" using red because it wasn't what they used in their example. That just does not follow logically at all.
Maybe I was being ridiculously dense 😄
 
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Which local code?
Plenty of data points on this forum of users reporting being denied by local codes across the United States and Canada. This isn’t a new point I’m bringing up; it has been discussed at length on this forum. It is also noted in the Tesla wall connector manual, which I showed previously above. If you can configure a circuit via software to something different than what the circuit was previously installed for, that is inherently unwise and unsafe. Safety regulations are made for idiots, not for smart people.
It is perfectly acceptable to install an outlet that has a higher rating that it’s over current protection device. Eg a 20 amp receptacle can be installed on a 15 amp circuit. The over current protection insures that more than the acceptable amount of current won’t be used, not the device. If someone set the charge to 48 amps but it was installed on a 20 amp breaker the breaker would trip.
That’s not what was being discussed at all, but putting a 20 amp outlet on a 15 amp circuit is not allowed in the NEC either. Anyone can do whatever they want but we aren’t talking about free will here, we are talking about codes and what is objectively safe and wise. Like I said earlier safety regulations are made for idiots, not for smart people. Here is a snippet from the NEC for evidence:

1647304182217.png

So, if the video showed Romex you would be arguing that Romex was prefered?
No, but maybe I was being a little dense lol
 
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qdeathstar

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Your code snippet is incomplete.

210.21(b)(1) says not less that the rating of the circuit. Your code snippet only applies if there is more than one device installed on the branch circuit.


Here is what 210.21(b)(3) says:

Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or, where rated higher than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.
 
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Your code snippet is incomplete.

210.21(b)(1) says not less that the rating of the circuit. Your code snippet only applies if there is more than one device installed on the branch circuit.


Here is what 210.21(b)(3) says:

Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform to the values listed in Table 210.21(B)(3), or, where rated higher than 50 amperes, the receptacle rating shall not be less than the branch-circuit rating.
Sure. So dedicated circuit = ok and not dedicated circuit = not ok. But again like I said earlier, this wasn’t what was being discussed.
 
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qdeathstar

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Sure. So dedicated circuit = ok and not dedicated circuit = not ok. But again like I said earlier, this wasn’t what was being discussed.


Of course it is what is being discussed. How is there any more danger in software limiting charging current compared to installing a 50 amp outlet on a 30 amp circuit?

They both “accomplish” the same thing, the potential for a device to be used that draws more current than the circuit is designed for. The point you are missing is the device doesn’t limit the current to the circuit, the over-current protection device (breaker) does.
 
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qdeathstar

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I used 4/3 romex with a 60AMP breaker. Got both from my local Lowes. Just left the extra wire capped, there for future use (if needed).

Tim

Where do you live at? I have never seen 4/3 anywhere. I think maybe you got ser cable, hopefully not aluminum.
079657A4-9D51-4E96-BB33-C6AF9248F187.png


To me at that point it just makes more since to get 6-2mc…
 
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