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

Wire size for wall charger

Rocky_H

Well-Known Member
Feb 19, 2015
7,297
8,987
Boise, ID
I suspect Rocky_H will weigh in soon. He mentioned some fairly obscure part of the NEC that allowed a 60A breaker when a 55 isn't available.
Heh, yeah, I don't usually get on the forum on the weekends, so I'm just now seeing this. Yes, that's the "round up" provision, but @iluvmacs covered that. You would still have to treat it as a 55A (or less) circuit.

Not what you paid for
I have 60A and the invoice from the electrician says 6-3.
This is the next thing I would use to address it. I'm a little bit unclear from your wording. Does the invoice state that it is to be a 60A circuit? If so, you did not get what you paid for. What you got is a code violation, and with that wire, you can only use it as a 50A circuit. So I would call the electrician back and offer him two choices to fix it or be reported to the inspector:
1. Redo the wire (for free) to actually make it the 60A circuit that you paid for
2. Give a partial refund since he only installed a 50A circuit and swap the breaker from 60 to 50.

I think a 50A circuit is totally sufficient and usable, but you shouldn't get ripped off by paying for more than that and not getting it.
 
  • Like
Reactions: MY-Y

DonaldBecker

Member
Aug 24, 2020
155
180
95033
I've always seen Al in grey, and never as small as 6 gauge (1970s excluded).

Aluminum wire is not generally available in sizes thinner than 8 AWG. In most areas it is common to use it only on 4 AWG and thicker, primarily because the extra cost for AL devices negates the extra cost of CU wire. Here, where it appears that corners might have been cut and the sheath is not the standard black color, it is worth checking that it's not actually 6/3 aluminum.
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,297
8,987
Boise, ID
Aluminum wire is not generally available in sizes thinner than 8 AWG. In most areas it is common to use it only on 4 AWG and thicker, primarily because the extra cost for AL devices negates the extra cost of CU wire. Here, where it appears that corners might have been cut and the sheath is not the standard black color, it is worth checking that it's not actually 6/3 aluminum.
The white sheath is a little bit odd. NM-B is usually black colored for these thicker wires, but maybe white is somewhat normal too. I just don't think this could be aluminum. If you look at ampacity tables, the column for NM-B cable type is under the group of copper wiring types, like so:
Ampacity Charts - Cerrowire
This picture shows it marked specifically as NM-B, which I think always means copper.
 

mcorf

Member
Apr 21, 2019
278
139
Campbell,Ohio
So I spoke with the electrician. He looked into it and said it is 6-3 and rated for 55 amps. But he said he checked with a building inspector before he installed mine since it was the 1st time he put in a Wall Charger and was told he could use the 6/3 with the 60 breaker. He was going to call a few others he knew and check with them and get back to me. His concern is that going with a 4g wire wouldn’t work with the current set up the way it was tunneled into the garage.
 

Rocky_H

Well-Known Member
Feb 19, 2015
7,297
8,987
Boise, ID
Holy frickin wow. This is disturbing and pathetic. Not your fault, though.
So I spoke with the electrician. He looked into it and said it is 6-3 and rated for 55 amps.
Yes, this is true.
But he said he checked with a building inspector before he installed mine since it was the 1st time he put in a Wall Charger and was told he could use the 6/3 with the 60 breaker.
Um, yeesh. Technically true, but it doesn't mean what he thinks it does. This is the thing that @iluvmacs covered. This guy is supposedly an inspector, damn it! He should know how this works! Using the "next size up" provision would say that since there isn't a 55A breaker size, you could use a 60A. But that DOES NOT auto-magically, hand-wavingly transform it into a genuine 60A rated circuit!! It's not. It's still limited by the wire size as a 55A maximum circuit. In all respects, in all calculations, it must not ever be treated as anything higher than a 55A circuit, even though it has an oversized breaker. Since the wall connector only has settings for 50 or 60, you're NOT ALLOWED to use the setting for 60!

Since you can't go over the limit, you have to stay under it. So you have to treat the whole thing as a 50A circuit in order to use the wall connector in code compliance with that 6/3 wire.

That "next size up" thing is rare and iffy to use, and it seems most of the time people misunderstand it, causing these problems. It's like asking, "Can I put a human's shirt on my dog?" Well, OK. "Hey, that thing has a human shirt on! That makes it a human!" Um, no. It's still just a dog that happens to have human clothes on.
 
Last edited:

mcorf

Member
Apr 21, 2019
278
139
Campbell,Ohio
Is he correct that the 4g wiring wouldn’t work with my current set up ?
 

Attachments

  • upload_2021-2-1_20-4-24.jpeg
    upload_2021-2-1_20-4-24.jpeg
    299.9 KB · Views: 61

MY-Y

Active Member
Mar 4, 2020
1,237
1,411
MD
If he can put conduit end to end, 6 gauge THHN works for a 60 amp circuit. I cut holes in my drywall and helped my electrician friend muscle 4-3 through holes he drilled my studs. Of course the right wire can be used, it just depends on how much work it is.

In hindsight, I would have used 4-2 on the HPWC, but still used the 4-3 for my spare 14-50 (in case I put an HPWC there later). 6 gauge MC would have been a good option as well.
 
  • Like
Reactions: craigery

TBrownTX

Member
Dec 25, 2020
966
1,134
Dallas, TX
In hindsight, I would have used 4-2 on the HPWC, but still used the 4-3 for my spare 14-50 (in case I put an HPWC there later). 6 gauge MC would have been a good option as well.

That's exactly what I did, 4/3 for potential 14-50 use in the future (sell house, change charger, etc.) In the meantime, I have an extra white wire capped off, no biggie.

Tim
 
Also I was curious about the white sheathing. Google tells me,
Before about 2001, most NM cable had a white outer jacket, but since 2001, most NM-B cable has been jacketed with a vinyl outer insulation that is colored to identify it for both consumers and inspectors. This color coding of the wire sheath is strictly voluntary, but most manufacturers have now followed suit in adhering to the color scheme.
 
  • Informative
Reactions: MY-Y and Rocky_H

Rocky_H

Well-Known Member
Feb 19, 2015
7,297
8,987
Boise, ID
Is he correct that the 4g wiring wouldn’t work with my current set up ?
I couldn't really tell from a picture like that. I think the concern about that is with conduit size. Was there some existing conduit that was already in place for part of this distance that they were pulling wires through? There are certain "fill" restrictions, where given a certain diameter of conduit it's only allowed to have X number of wires of X gauge thickness in it. And that may have been what he was talking about, where they wouldn't be allowed to fit the 4 gauge wires in the conduit that was there because of it being too small.
 

iluvmacs

Member
Jan 27, 2014
519
899
Madison, WI
If you can fit 6/3 NM then you can fit two #6 THHN and one #10 THHN. Unless there is a reason you wanted the neutral for future changes. I think you'd need a minimum 3/4 inch conduit.
Just because NM cable was fished through finished walls doesn't mean that conduit could be. That's typically much more invasive, especially when it comes to bends. At minimum, it's way more labor-intensive.

Yes. 3/4" conduit would be typical. No reason for neutral wire -- even if you decide you want it later, just add it then for minimal effort. You don't necessarily need a ground wire for the whole length if you bond it to the conduit near the HPWC.
 

bmil03

Member
Mar 14, 2020
24
21
ILannoy
I couldn't really tell from a picture like that. I think the concern about that is with conduit size. Was there some existing conduit that was already in place for part of this distance that they were pulling wires through? There are certain "fill" restrictions, where given a certain diameter of conduit it's only allowed to have X number of wires of X gauge thickness in it. And that may have been what he was talking about, where they wouldn't be allowed to fit the 4 gauge wires in the conduit that was there because of it being too small.

@Rocky_H do you think the wire size/breaker issue @mcorf has posted within this thread has any correlation to thread below he started recently?

Wall charger question
 

TBrownTX

Member
Dec 25, 2020
966
1,134
Dallas, TX
View attachment 633419 The wire was run from my breaker box in the basement on top of the drop ceiling behind the drywall in my garage. The only place there is a 3/4 inch conduit is when it comes outside the drywall,.

Personally, I'd just set them both a 50AMP and leave it be, unless you really go a long distance everyday and need the extra speed to charge overnight. Breaker replacement would be optional with the provisioning adjustment.

Tim
 

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