Gen 3 wall connectors: 2 on same circuit?

[CdnElec]

Hi everyone,

There seems to be some inconsistent messaging regarding gen 3 wall connectors needing their own single circuit. Typically, any EVSE needs to have its own circuit, but if they have automatic load balancing, the NEC allows for a shared circuit.

In my case: I have 6/3 AWG to the garage powered by a single 60 amp circuit currently to 1 wall connector. I am awaiting delivery on my second one. The easiest scenario is to splice the line once it enters the garage using polaris connectors in order to separate into 2 different runs from that box and have both wall connectors sharing that same circuit. The second scenario would be to install a subpanel with 2 60 amp breakers instead. But with the power sharing (and redundant protection of only utilizing half the charging speed if the connection is offline), I do not see the need for the separate circuits.

If anyone has thoughts or experience with installing 2 3rd gen wall connectors, please let me know what you have done!

 

[Ostrichsak]

You cannot put two Gen 3 HPWC on the same circuit. The Gen 2 was capable of that but not the newest Gen 3. Gen 3 must be on its own circuit for each HPWC.

 

[CdnElec]

You cannot put two Gen 3 HPWC on the same circuit. The Gen 2 was capable of that but not the newest Gen 3. Gen 3 must be on its own circuit for each HPWC.

Can you help me to understand why? This seems like functionality that would be useful, so why take it away? Aside from Tesla's own documentation recommending separate circuits, the NEC seems to allow for it. And if it 'must' be. What is the consequence if not? I will do it the right way, just curious.

 

[CdnElec]

 

[CdnElec]

This also complicates the message, straight from Tesla: Gen 3 Wall Connector Power Sharing

 

[brkaus]

I was told code dies not allow it anymore. Or at least our local AHJ.

I can have a 60a breaker going to a 60a sub panel with two 60a breakers, each going to a WC setup for load sharing.

However I cannot use Polaris connectors and split the circuit.

Just what I was told by two electricians. One of which was willing to go the Polaris route had I don’t two WC at initial install in 2017.

Btw - a small sub panel isn’t much more than the cost of the Polaris connectors. But then there is the question of a neutral or not required in the sub panel. And there I get conflicting answers from the electricians I’ve talked to.

 

[CdnElec]

I was told code dies not allow it anymore. Or at least our local AHJ.

I can have a 60a breaker going to a 60a sub panel with two 60a breakers, each going to a WC setup for load sharing.

However I cannot use Polaris connectors and split the circuit.

Just what I was told by two electricians. One of which was willing to go the Polaris route had I don’t two WC at initial install in 2017.

Btw - a small sub panel isn’t much more than the cost of the Polaris connectors. But then there is the question of a neutral or not required in the sub panel. And there I get conflicting answers from the electricians I’ve talked to.

I have all wires available for the sub panel as I ran 6/3 to the garage. If necessary, I can do it the proper way

 

[rwojo]

It's not that the Gen 3 isn't capable of it (in that electrically, physically, etc), it's that they wrote the docs matching the NEC 2020 code. Sadly NEC §110.3(B) makes that a part of being in code.

NEC 2023 allows for this in §625.40 and I'm trying to get Tesla to match their documentation. I talked to some of their installer support team today and they said more guidance on this may be coming out this year as they revamp some things on their end. No promises, but friendly in ack'ing that the code changed.

The web page is confusing as it says things like "Note: In the event that your leader and followers have different circuit breakers" implying that they can have the same circuit breaker, although maybe they are thinking the upstream that feeds the subpanel. *shrug*

Check out these threads as well and watch them for updates.

Gen3 Wall Connector Question - load sharing?

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...

teslamotorsclub.com

Gen 3 Charger Power Sharing - who has this working?

If I use the Lectron Tesla to J1772 adapter to allow for non-Tesla vehicles to charge is is going to work? Adapter link I think the question is really more something like : Is the Wall Connector itself discovering the required power of each vehicles Is the vehicle supposed to request an amount...

teslamotorsclub.com

 

[bjhinkle]

Your first scenario is my exact setup. It works great.

“I have 6/3 AWG to the garage powered by a single 60 amp circuit currently to 1 wall connector. I am awaiting delivery on my second one. The easiest scenario is to splice the line once it enters the garage using polaris connectors in order to separate into 2 different runs from that box and have both wall connectors sharing that same circuit.”

There is no issue here as long as you set up power sharing. Glad to answer any questions about it.

 

[bjhinkle]

To be clear, both my chargers are Gen3. You cannot mix Gens while power sharing.

 

[rwojo]

To be clear, both my chargers are Gen3. You cannot mix Gens while power sharing.

Ah, so you decided to use a Polaris instead of subpanel for a Gen 3? Technically not allowed per the install manual, but obviously works completely fine and within NEC 2023 code.

 

[bjhinkle]

yeah, I used Polaris. To me it’s logically the same as any shared circuit like lights and switches connected with waygo or twists. Just with higher current and larger gauge. And Polaris is pretty robust compared to those. .

A panel with 2 more breakers doesn’t make sense since there is already a 60a breaker. And the WCs are smart enough to keep max load at 48a working together. Maybe there is a good reason otherwise, but my electrician seemed to think it was fine.

 

[rwojo]

Maybe there is a good reason otherwise, but my electrician seemed to think it was fine.

Agreed, alongside my interpretation of the spirit and letter of the code as well.

 

[brkaus]

yeah, I used Polaris. To me it’s logically the same as any shared circuit like lights and switches connected with waygo or twists. Just with higher current and larger gauge. And Polaris is pretty robust compared to those. .

A panel with 2 more breakers doesn’t make sense since there is already a 60a breaker. And the WCs are smart enough to keep max load at 48a working together. Maybe there is a good reason otherwise, but my electrician seemed to think it was fine.

What did the inspector say?

 

[miimura]

What did the inspector say?

What inspector?

 

[CdnElec]

Thanks for the input all. I ended up doing a subpanel with 2 circuits for each wall connector. Very impressed with the dynamic changing

 

[Rocky_H]

Thanks for the input all. I ended up doing a subpanel with 2 circuits for each wall connector. Very impressed with the dynamic changing

There is a reason why the circuit sharing method changed between the Gen2 and the Gen3 wall connectors. On the old Gen2, you had to pick one amp level, and that was it. It had to be the same for all of the wall connectors on that network. So since the current level was always going to be the same, you also had to wire to support that to all of them, so they allowed direct wiring together of the power connections with Polaris connectors.

But with Gen3, you are allowed to pick various current levels for the different units in the sharing network, like 2 15A ones and 2 60A ones, so Tesla requires you not just bond all of the wires together, but to use a breaker per each one to make sure it all meets spec with the wire thickness to each one too. But it is still effectively sharing one "parent" supply line that goes into the subpanel.

There seems to be some inconsistent messaging regarding gen 3 wall connectors needing their own single circuit.

Yeah, that's because people are disagreeing over what they mean by the word "circuit". Technically, in NEC terminology, if you run a line to a subpanel, and then split that with individual beakers, those are each "branch circuits". But here in the Tesla forum, when people are asking, "Can I share a circuit?" they are referring to the main parent feeder line that goes to the garage before it gets split.

 

[rwojo]

But with Gen3, you are allowed to pick various current levels for the different units in the sharing network, like 2 15A ones and 2 60A ones, so Tesla requires you not just bond all of the wires together, but to use a breaker per each one to make sure it all meets spec with the wire thickness to each one too. But it is still effectively sharing one "parent" supply line that goes into the subpanel.

Prior to NEC 2023 perhaps, but I don't understand why that would matter with the latest code.

The Energy Management System (EMS) can control the loads and allows the service, feeder and branch circuits to be oversubscribed. Tesla Power Sharing fits the definition of an EMS, including 750.30(C)(5) of password protecting the setting, etc.

In the case you mentioned with 2x 15A and 2x 60A, you can just run 6 AWG THHN to all four, and set the current limits on the two 15A per the Tesla docs directly on each unit, then the network limit to 60A for example. You can always oversize a wire, and the branch circuit breaker keeps things in check along with the EMS.

An aside, I spoke to a few Tesla certified installers and they are already installing Gen3s (mostly in commercial settings for car parks, dealers, etc) with taps/bonding, not separate breakers. Now just waiting for official guidance for all of us...

 

[Rocky_H]

Prior to NEC 2023 perhaps, but I don't understand why that would matter with the latest code.

It sounds like you're disagreeing with something, but I can't make out what. A managed load sharing function is spelled out specifically as an allowed exception to the dedicated circuit thing in the last several NEC versions. This is allowed.

The Energy Management System (EMS) can control the loads and allows the service, feeder and branch circuits to be oversubscribed. Tesla Power Sharing fits the definition of an EMS, including 750.30(C)(5) of password protecting the setting, etc.

Yes, I know. It sounds like you think I was saying the opposite.

In the case you mentioned with 2x 15A and 2x 60A, you can just run 6 AWG THHN to all four, and set the current limits on the two 15A

But you DON'T HAVE TO. That is the purpose of this. You can use thinner wire to save cost on some of these if something like a hotel is going to put in a bank of a bunch of wall units and don't need them all to be 60A wire capable for overnight usage.

An aside, I spoke to a few Tesla certified installers and they are already installing Gen3s (mostly in commercial settings for car parks, dealers, etc) with taps/bonding, not separate breakers. Now just waiting for official guidance for all of us...

Then they are violating code by not following the manufacturer's installation instructions. The Gen3 wall connector manual shows how it has to be done, and it should use a breaker for each unit.

 

[rwojo]

Yes, I know. It sounds like you think I was saying the opposite.

Sorry, I'm just saying that the Tesla PDF manual (not website) seems to just be written without the option that would pass code if written today.

But you DON'T HAVE TO. That is the purpose of this. You can use thinner wire to save cost on some of these if something like a hotel is going to put in a bank of a bunch of wall units and don't need them all to be 60A wire capable for overnight usage.

Right, it is an option. Having the option should allow for installations with the larger same sized wiring without breakers objectively when looking at the latest code. But it isn't as we know...

Then they are violating code by not following the manufacturer's installation instructions. The Gen3 wall connector manual shows how it has to be done, and it should use a breaker for each unit.

To just play with this a bit, the website page which is newer than the manual is being interpreted by both Tesla employees part of their installer network support and installers as being the latest guidance and that separate breakers are not necessary. Does that pass 110.3(B)? Dunno. It's not as explicit as I would like, so right now it is the interpretation (without clear diagrams, etc) that is debatable I suppose.

What we really need here is a written addendum from Tesla. That's where the energy should be focused for sure.

Until then, Tesla tells installers it is OK and they are doing it LOL