Welcome to Tesla Motors Club
Discuss Tesla's Model S, Model 3, Model X, Model Y, Cybertruck, Roadster and More.
Register

Gen 3 - Wall connector install (wires, amperage, etc)

alset2020

Member
Aug 23, 2020
10
5
Ottawa
Hi all,
My electrician is coming to install the Gen 3 Wall connector and just wanted to inquire whether his setup makes sense. Kinda new to this so just wanted to confirm with the community. I have a 125amp panel (older home).

The electrician is planning on installing a 60A breaker, using 6/2 Lumex wiring but he mentions that he cannot "program the charger over 40A." I have a Model 3 SR+ so I am aware the max it can pull is 32A however we are planning on maybe upgrading in the future and would hope to be able to utilize the full 48A. So is he correct in saying he can program it to a 40A limit? How is he able to limit it to 40A? Am I able to eventually increase it to 48A in the future if needed? And is the 6/2 Lumex wiring sufficient?

Thanks so much!!
 

iluvmacs

Member
Jan 27, 2014
489
829
Madison, WI
I see you're in Canada, so I'm not sure of what your electric code says about this. In the US, we use a cable called Romex that I believe to be similar to or the same as your Lumex. In the US, 6/2 Romex is not allowable for 60A circuits. If this is also the case there, then you are limited to a 50A circuit for your HPWC (including that circuit breaker), and thus 40A charging. BUT... maybe it's allowable for 60A there, and I just don't know.

If none of this is an issue there, it's very possible that 40A is the most you can take out of your 125A service. That comes down to your other power draw, especially other high-power appliances. Your electrician should easily be able to tell you this fact if it's the case. Though... it's also unclear from your post if the reported 40A limit is the circuit rating (and thus 32A charging) or the charging limit (and thus 50A circuit). Might want to find that out too :).
 
  • Like
Reactions: alset2020

fiehlsport

Member
Jul 30, 2020
54
23
Binghamton, NY
Sounds correct. 6ga wiring is only allowed for 60A breakers (48A continuous charging) if it is THHN (individual conductors) pulled through conduit in the US. If it is Romex/Lumex, it has a 50A limit, so the 40A continuous charger limit would be correct. (80% rule)

There is no reason for them to be installing a 60A breaker if they are using 6/2 Lumex. You should ask if they can upgrade the wiring to support the 60A/48A situation - that's what you want for the future.
 

TheRFMan

Member
Dec 15, 2019
554
428
Ottawa, Canada
Sounds correct. 6ga wiring is only allowed for 60A breakers (48A continuous charging) if it is THHN (individual conductors) pulled through conduit in the US. If it is Romex/Lumex, it has a 50A limit, so the 40A continuous charger limit would be correct. (80% rule)

6 gauge Loomex/Romex (part of the NMD90 class of wiring here in Canada) is rated for up to 55A. However, there are no 55A breakers, so a 50A breaker would normally be fitted. That type of wire is the go-to fot residential 50-amp circuits, such as kitchen range circuits.

If you want a full 60A circuit, you need to go with single conductors inside a conduit. Depending on the length and location of your electrical run, that may or may not be feasible. The difference between charging at 40A and 48A is not a deal-breaker at all for me, and not worth the hassle of running conduit from the panel to the garage.
 
  • Like
Reactions: alset2020

Rocky_H

Well-Known Member
Feb 19, 2015
7,070
8,684
Boise, ID
(I got pulled away to lunch when I had this post mostly composed, and I see that other people put in answers before I got back to finish, so I'm mostly just agreeing.)

The electrician is planning on installing a 60A breaker, using 6/2 Lumex wiring [...] And is the 6/2 Lumex wiring sufficient?
This was really confusing me, so I did some Googling, and I found this on a site that sells it:
" It is commonly known as “Lumex” (or Romex for our American friends)."
Gotcha. Yeah, I hear of Romex all the time here in the U.S.

So now to answer this question, no, that is a problem. There is nothing wrong with Romex at all, but using 6 gauge thickness, that is only rated up to 55A circuits. You cannot have that with a 60A breaker. 6/2 Romex would limit that where it would need to be only a 50A circuit. If you want to eventually be able to move this up to a 60A circuit, providing 48A, you would need to go to the next size up wire, 4/2 Romex (or Lumex). Here's a table of amp ratings for different types of wire:
Ampacity Charts - Cerrowire
That first column, where it says NM-B is Romex/Lumex.

but he mentions that he cannot "program the charger over 40A." I have a Model 3 SR+ so I am aware the max it can pull is 32A however we are planning on maybe upgrading in the future and would hope to be able to utilize the full 48A. So is he correct in saying he can program it to a 40A limit? How is he able to limit it to 40A? Am I able to eventually increase it to 48A in the future if needed?
The wall connector has a wi-fi interface, where you can set up what level of circuit it's on, so it can be set for many levels. I'm just generally confused at what the electrician was saying though. With a 50A rated circuit, it can only have a 40A continuous draw, so maybe that's what he's talking about, and that would be appropriate for this wire size. But then why would he ever consider putting a 60A breaker on it?
 

alset2020

Member
Aug 23, 2020
10
5
Ottawa
(I got pulled away to lunch when I had this post mostly composed, and I see that other people put in answers before I got back to finish, so I'm mostly just agreeing.)


This was really confusing me, so I did some Googling, and I found this on a site that sells it:
" It is commonly known as “Lumex” (or Romex for our American friends)."
Gotcha. Yeah, I hear of Romex all the time here in the U.S.

So now to answer this question, no, that is a problem. There is nothing wrong with Romex at all, but using 6 gauge thickness, that is only rated up to 55A circuits. You cannot have that with a 60A breaker. 6/2 Romex would limit that where it would need to be only a 50A circuit. If you want to eventually be able to move this up to a 60A circuit, providing 48A, you would need to go to the next size up wire, 4/2 Romex (or Lumex). Here's a table of amp ratings for different types of wire:
Ampacity Charts - Cerrowire
That first column, where it says NM-B is Romex/Lumex.


The wall connector has a wi-fi interface, where you can set up what level of circuit it's on, so it can be set for many levels. I'm just generally confused at what the electrician was saying though. With a 50A rated circuit, it can only have a 40A continuous draw, so maybe that's what he's talking about, and that would be appropriate for this wire size. But then why would he ever consider putting a 60A breaker on it?

Yes that is what I'm confused with as well. So from what I'm understanding is that the limitation of 40A is basically a result of the wire itself which as mentioned can only provide up to 50A. And the only way to get 48A is to use a 4/2 Romex (or Lumex).

Thanks everyone for all the replies!!
 

TheRFMan

Member
Dec 15, 2019
554
428
Ottawa, Canada
Yes that is what I'm confused with as well. So from what I'm understanding is that the limitation of 40A is basically a result of the wire itself which as mentioned can only provide up to 50A. And the only way to get 48A is to use a 4/2 Romex (or Lumex).

Hi there... fellow Ottawan here.

Technically, that 6/2 Romex/Loomex is OK up to 55A, but it's a moot point since they don't make 55A breakers, and there is no 44A charging setting on any chargers. So your conclusion that the charging limit is 40A because of the wire is correct.

However, you do not need to go to 4/2 Romex/Loomex for 60A. In fact,I've never actually seen 4/3 or 4/3 Romex, and it would be horribly difficult to bend and hard to work with. For a 60A circuit, electricians will generally run electrical conduit and run the individual conductors in the conduit. The individual conductors dissipate heat better than the Romex bundle, so separate 6 gauge conductors in a conduit can go to 60A (perhaps even a bit more). The logistics of running conduit can be unwieldy however. I'd just run the 6/2 Loomex/romex and charge at 40A and be done with it.

I'm not a licensed electrician, so take this as you wish. I am a licensed professional electrical engineer in Ontario and I know this stuff pretty well however.
 

Products we're discussing on TMC...

About Us

Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.

Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


SUPPORT TMC
Top