Gen3 Wall Connector Question - load sharing?

[k.alexander]

If you have a 120A feeder circuit to a sub-panel with two 60A breakers, one for each Wall Connector, then you don't need load sharing at all.
Now, if you can only put a 100A breaker in your main panel because of the other loads, then load sharing will help you get the full 48A to any one car and 40A to two simultaneously.

Ok, I guess that makes sense. I didn't think of it, but I guess one doesn't have to enable power sharing between 2 Gen 3 HPWC.

That said, my question remains, with a 120A feeder (this is theoretical) to a sub-panel with two 60A breakers, AND power sharing turned on, the two HPWC will still be able to provide full 48A of electricity simultaneously? I really just want to understand why someone elsewhere said that they 2 HPWC can only share up to 64A--seems like that's wrong.

And last question, practically speaking (as there seems to be some wacky reports of slow ramp up to 48A, etc., on here) what can one expect out of 2 HPWC charging two vehicles at the same time, if they're on say an 80A or 90A feeder line to a sub-panel with 60A breaker for each HPWC? Will one, in real world, get 48A out of one and how much out of the other?

And a last, last question. Regarding the 125% rule applying to continuous power supplies, which of these is correct, is it (48+48)x1.25 or is it (60+60)x1.25?

 

[Rocky_H]

Heh, that is kind of funny where you asked about getting an answer about sharing, but then accidentally proposed a hypothetical where they wouldn't need to share at all with a 120A line. Credit to @miimura for preemptively answering this. I don't think I could add anything. I hadn't heard of any artificially lower total limit of amps. But I don't use any Gen3 wall connectors, so I can't give any firsthand info about it. I would say maybe check what the manual says, but since the manual was a lying piece of garbage that said, "You can share!!" for over a year before sharing became available, I wouldn't trust that as far as I could throw it.

I do think the current version of the sharing firmware is only enabling sharing up to 4 units together. So as far as I know, you could run things like 100A or 200A main lines to split.

 

[k.alexander]

Heh, that is kind of funny where you asked about getting an answer about sharing, but then accidentally proposed a hypothetical where they wouldn't need to share at all with a 120A line. Credit to @miimura for preemptively answering this. I don't think I could add anything. I hadn't heard of any artificially lower total limit of amps. But I don't use any Gen3 wall connectors, so I can't give any firsthand info about it. I would say maybe check what the manual says, but since the manual was a lying piece of garbage that said, "You can share!!" for over a year before sharing became available, I wouldn't trust that as far as I could throw it.

I do think the current version of the sharing firmware is only enabling sharing up to 4 units together. So as far as I know, you could run things like 100A or 200A main lines to split.

Thanks @Rocky_H

How about my late-addition question:
Regarding the 125% rule applying to continuous power supplies, which of these is correct, is it (48+48)x1.25 or is it (60+60)x1.25?

 

[Maybe22]

Is anyone loadsharing with 2 Gen 3 wall connectors and getting expected results, namely, each vehicle will charge at 48 amps if either it is the only one plugged in or of the other is plugged in but already fully charged, and otherwise the software will share the available current in some way between the 2 vehicles? Ty

 

[Rocky_H]

How about my late-addition question:
Regarding the 125% rule applying to continuous power supplies, which of these is correct, is it (48+48)x1.25 or is it (60+60)x1.25?

I think you're overcomplicating it. The first one is correct, but you can do the math either way. It's a 48A draw on a 60A circuit. Double the 60A and it's 120A to do a full double circuit. Or you could double the 48A draw and then multiply by 1.25 and it still comes out to 120A total.

 

[k.alexander]

I think you're overcomplicating it. The first one is correct, but you can do the math either way. It's a 48A draw on a 60A circuit. Double the 60A and it's 120A to do a full double circuit. Or you could double the 48A draw and then multiply by 1.25 and it still comes out to 120A total.

Oh, I'm known for overcomplicating things...just ask my wife j/k.
Anyways, I think I got I understand. You helped me with some of this a few weeks back, but I think the new plan is to run #2Al wire, which I believe is rated for 90A, which I guess gives me 72A of continuous draw. Will likely just have the electrician set up a sub-panel in the garage now, put one 60A breaker for my 6-50 outlet for now, but ultimately be able to swap that out and install two HPWC if the need for the second ever arises. Seems like with #2Al I can get considerably more amps to the garage than with #6Cu, and likely for same money or cheaper, and add a little more future-proofing.

 

[Rocky_H]

but I think the new plan is to run #2Al wire, which I believe is rated for 90A, which I guess gives me 72A of continuous draw. Will likely just have the electrician set up a sub-panel in the garage now,

Yep, that looks like a good plan. Aluminum apparently is quite a bit cheaper than copper for long runs and can save some money on this part of the installation, and I do see 90A capability there. The subpanel is important there, as the Tesla wall connector lugs aren't made to allow aluminum connections. Most subpanels can take either copper or aluminum, and the aluminum wire has to be done a certain way with the anti-oxidation goop and all that. Then you can do the shorter final run with copper to the wall connector or outlet or whatever.

put one 60A breaker for my 6-50 outlet for now,

No--I thought we've been over that multiple times. The breaker is NEVER allowed to be higher than the outlet rating. You can't do a 60A breaker yet if you're doing a 6-50 outlet.

Seems like with #2Al I can get considerably more amps to the garage than with #6Cu, and likely for same money or cheaper, and add a little more future-proofing.

Yes, sounds like a good main run to the garage.

 

[k.alexander]

@Rocky_H - Yep, that's the plan, i.e. to run #2Al to the garage. Broke the news to my electrician, he didn't seem "too upset" by it, whereas he was arguing with me about something else related to #6Cu. But we didn't talk at length. Anyways, going to make him do this. And at this point thinking of having him run a 4 gauge wire, because I don't think the price difference is going to be significant on the aluminum; and have him put in a sub-panel in the garage right away (as I am aware that I'll need one to accommodate the Aluminum connections at one point or another/eventually).

Main concern now is that there is enough "capacity" (is that the right word) in the house for that 90A run. It won't be an issue now with one 6-50, but if and when I ever go to 2 HPWC and try to draw that whole 90A, it may present an issue. Trying to get someone to do a load calculation for me.

And yes, I knew when I was typing it that a 60A breaker on a 6-50 outlet is incorrect. Thanks for correcting me, again

 

[RudeDude]

Plenty of good and useful information in this thread here. Thanks all! I did decide to look at the most recent codes because the Gen 3 installation manual still shows one breaker (branch circuit) PER wall connector.

I am NOT a lawyer and I am NOT a certified electrician. So, as I read it, the code does allow multiple WC per branch circuit because of the load sharing.

NFPA section 70 (National Electrical Code) - Year 2023

NFPA LiNK®

The leading information and knowledge resource on fire, electrical and related hazards.

link.nfpa.org

Chapter 6: 625 Electrical Vehicle Power Transfer System
Part III: Installation
625.40 Electric Vehicle Branch Circuit
- Each circuit supplying EVSE greater than 16 amp or 130 volt must have its own branch circuit
- Except: 625.42.(A) or (B)

Where those sections define the shall / shall not for energy management systems which can coordinate/limit the total draw.

I also posted on this other thread Gen 3 Charger Power Sharing - who has this working?

 

[rwojo]

Plenty of good and useful information in this thread here. Thanks all! I did decide to look at the most recent codes because the Gen 3 installation manual still shows one breaker (branch circuit) PER wall connector.

I am NOT a lawyer and I am NOT a certified electrician. So, as I read it, the code does allow multiple WC per branch circuit because of the load sharing.

Your research on this and the other thread citing the parts of the NEC code was great.

I've been wondering the same thing on my side though, and the darn NEC catch all of 110.3(B) saying "Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling."

I contacted Tesla to see if the NEC 2023 changes the manual instructions to allow for same branch load sharing, I suggest everyone do the same that is interested in this!