Any electricians here?

[brkaus]

properly configured load sharing set to 60a breaker (48a charging) should be OK on a single breaker that is split by splices. Wiring for each needs to support 60a.

That used to be the standard process per my electrician.

However, my electrician as of now, the only way he can do it now is with two circuits at 60a each.

- They can be 60a each to the main panel.
- They can be 60a to a sub panel, and then two 60a circuits from there.

In both of above cases, 60a would still be used for the load calc due to load sharing.

- it is not required that the sub panel be on a 100a circuit. 60a is fine.
- this example can be scaled to any number, based on the capacity of your house.

he said splices are still ok in his mind, but no longer allowed. He did not tell me why the change.


source of info - I had a quote several years ago to have a second WC2 installed. I just had the quote “refreshed” last week. Of course, wc2 requires comm cable between the two and WC3 uses wifi (latest firmware), but he said that was effectively no different.

 

[MN-MS100D]

Tesla has now implemented load sharing on the Wall Connector 3. Wall connectors can now intelligently share a single circuit, up to 4 wall connectors. Gen 3 Wall Connector Power Sharing

Page 24 of the manual is clear to me that each HPWC needs a dedicated branch circuit.

 

[ZilWin]

I think your electrician did not install things correctly. Two 60 amp branch circuits are needed: One routed to each HPWC. That is what the diagrams indicate is required. The sub panel shown would need to have a 100A breaker upstream.

That's correct....in a perfect world. We have no idea what the OPs load center looks like or whether he has additional space for a second 60A breaker. Could be the Electrician did it the way that would work for the customer within the limitations of the system. in reality each of the WCs looks back at a 60A breaker. As long as load sharing is set up correctly they should share the charge duties the same as if they were separately breakered. Is it to Code? maybe not. should it work safely? yes.
I find the whole discussion very interesting and the feature of load sharing very forward looking by Tesla. Planning for multiple EVs per household is something not many people are thinking about....Yet.

 

[a1machinista1]

That's correct....in a perfect world. We have no idea what the OPs load center looks like or whether he has additional space for a second 60A breaker. Could be the Electrician did it the way that would work for the customer within the limitations of the system. in reality each of the WCs looks back at a 60A breaker. As long as load sharing is set up correctly they should share the charge duties the same as if they were separately breakered. Is it to Code? maybe not. should it work safely? yes.
I find the whole discussion very interesting and the feature of load sharing very forward looking by Tesla. Planning for multiple EVs per household is something not many people are thinking about....Yet.

This is the only reason I am questioning it in the first place. This whole concept of load sharing. I would imagine that the electrician is as new to it as I am.

 

[brkaus]

If you want to remove all doubt, the splice box could be replaced with a small sub-panel.

100-Amp 6-Spaces 12-Circuit Main Lug Load Center https://www.lowes.com/pd/Square-D-100-Amp-6-Spaces-12-Circuit-Main-Lug-Load-Center/3127883

There are also 2/4 space ones available, my search-foo is failing at the moment.

 

[a1machinista1]

If you want to remove all doubt, the splice box could be replaced with a small sub-panel.

100-Amp 6-Spaces 12-Circuit Main Lug Load Center https://www.lowes.com/pd/Square-D-100-Amp-6-Spaces-12-Circuit-Main-Lug-Load-Center/3127883

There are also 2/4 space ones available, my search-foo is failing at the moment.

I'm going to call the electrician this morning and talk with him about it. From what I have gathered the current install is good as long as power sharing is enabled AND does its job. I THINK this set up might leave me in a non optimal position if for some reason the "leader" connector can not communicate with the "follower" connector?? Yes a small sub panel with two 60a breakers I THINK would be better if I keep the output at 60a on each connector. OR I could set each connector to a max of 30a but then Will only get 30a when a single car is plugged in. Which kind of defeats the purpose of power sharing...

 

[brkaus]

@a1machinista1 the 60a breaker in the main panel should protect the wiring in case power sharing fails.

I believe the follower will cease charging if it cannot talk to the leader. They may also drop back to total divided by number if WCs.

the biggest risk is mis-configuration.

 

[a1machinista1]

@a1machinista1 the 60a breaker in the main panel should protect the wiring in case power sharing fails.

I believe the follower will cease charging if it cannot talk to the leader. They may also drop back to total divided by number if WCs.

the biggest risk is mis-configuration.

Configuration as in allocation of amps per connector? I set each one to 60a. That is the max allowable in the UI and the size of the breaker. I was going to set at 30a each but then I don't get full charge when only one car is plugged in. I was thinking, I'm sure it works both ways? If I plug the "follower" into a single car then at some point plug in another car to the "leader" it must still know (once I push the button) that I'm going to plug another car in and will drop the amps? You think?

 

[ZilWin]

If you want to remove all doubt, the splice box could be replaced with a small sub-panel.

100-Amp 6-Spaces 12-Circuit Main Lug Load Center https://www.lowes.com/pd/Square-D-100-Amp-6-Spaces-12-Circuit-Main-Lug-Load-Center/3127883

There are also 2/4 space ones available, my search-foo is failing at the moment.

Nice! I did the same thing with my backyard Spa and outdoor lighting circuits. Small subpanel with seperate breakers for each appliance.

 

[ucmndd]

he said splices are still ok in his mind, but no longer allowed. He did not tell me why the change.

The “why” is the snippet of the 2017 NEC that @DerbyDave posted upthread stipulating that EVSEs must be installed as singular devices on dedicated branch circuits.

Not every locality has adopted the 2017 NEC yet, although Oregon has, which is what OP’s profile says.

Edit: I looked at Dave’s comment again and note it’s actually in reference to receptacles for EV charging, not hard wired EVSEs. However I believe there were other significant updates to the 2017 NEC regarding EVSEs as well. Additionally, Tesla’s pretty clear about the way they want things installed in the manual, with each unit on its own breaker.

 

[a1machinista1]

That's good to know on my end.

 

[ucmndd]

Be sure you see my edits above RE receptacles vs. hard wired EVSEs.

 

[DerbyDave]

Be sure you see my edits above RE receptacles vs. hard wired EVSEs.

Can someone post the new Tesla Wall Connector installation instructions that include multiple connector sharing? Thanks.

 

[brkaus]

@ucmndd that's the part that confused me. Anyway, my initial quote was from 2017 which would have been before 2017 code was adopted here.

I know it's off topic, but is the ability to charge for power available yet? I didn't know the sharing was even available yet for the WC3. Just a pointer to a thread if it exists would be appreciated.

 

[Rocky_H]

Several points about this:

1. Yeah, the thing about dedicated was about receptacles, not hard-wired devices.

2. This installation is wrong. The installation instructions say you must use a breaker for each one--no splices or Polaris connectors.

3. The thing about dedicated branch circuits... Well, I'm not sure exactly how that is defined. You can run one 60A line most of the way to a subpanel, and then put up to four 60A breakers there to split it out. That can work because of the circuit sharing. So that's shared, not fully individual and dedicated all the way back to the main, but as far as how "branch circuit" is defined, this does have an individual breaker at the end at the subpanel, so that may make each one a "branch circuit".

 

[a1machinista1]

Several points about this:

1. Yeah, the thing about dedicated was about receptacles, not hard-wired devices.

2. This installation is wrong. The installation instructions say you must use a breaker for each one--no splices or Polaris connectors.

3. The thing about dedicated branch circuits... Well, I'm not sure exactly how that is defined. You can run one 60A line most of the way to a subpanel, and then put up to four 60A breakers there to split it out. That can work because of the circuit sharing. So that's shared, not fully individual and dedicated all the way back to the main, but as far as how "branch circuit" is defined, this does have an individual breaker at the end at the subpanel, so that may make each one a "branch circuit".

Correct, it does say breakers on individual circuits. But it also shows a schematic for no sub panel and running up to four connectors off of one supply. Hence, my questions. I have not received a call from the electrician yet.

 

[a1machinista1]

No, Load sharing will charge 1 car at 48A regardless of which Wall Connector it is plugged into, or both cars at 24A.

If each connector was set to 48a (60a)? Since they both have to be able to pull 48a amps individually if only charging one car then it makes sense that both need to be set at 48a (60a) and the power sharing software will decide who gets what?

 

[a1machinista1]

That's correct....in a perfect world. We have no idea what the OPs load center looks like or whether he has additional space for a second 60A breaker. Could be the Electrician did it the way that would work for the customer within the limitations of the system. in reality each of the WCs looks back at a 60A breaker. As long as load sharing is set up correctly they should share the charge duties the same as if they were separately breakered. Is it to Code? maybe not. should it work safely? yes.
I find the whole discussion very interesting and the feature of load sharing very forward looking by Tesla. Planning for multiple EVs per household is something not many people are thinking about....Yet.

If I had room for a second 60a breaker in my panel I would not have the need for load sharing a single 60a supply. Correct? Remember I am NOT an electrician. I totally understand and feel confident (kind of) that both of these connectors will work the way they are wired, AS LONG AS THE SOFTWARE DOES ITS JOB!! in the case that the software does not allocate the total 60a supply correctly then I see an issue with not having individual circuits with their own breakers. Again, I am NOT an electrician.

 

[beatle]

This page isn't Tesla-specific, but it does reference oversubscribing a breaker with multiple EV chargers, assuming there is an automatic load management system, such as this company's software. I think Tesla's HPWC communication would fall under that umbrella.

Clearing up Confusion over electric vehicles and smart charging

Did you know that for charging stations to operate above 80% of their capacity, it is necessary to have an intelligent load management system to maintain control of the load.

www.ampcontrol.io

Ampcontrol quotes the NEC here:

Section 625.42 also states:

“Where an automatic load management system is used, the maximum equipment load on a service and feeder shall be the maximum load permitted by the automatic load management system.”

The silly thing is that it seems like you can "legally" oversubscribe the main panel breaker that feeds a subpanel of EV circuits. i.e. install a subpanel fed from a a 60A circuit from the main panel, and install two 60A circuits on the subpanel, each feeding a HPWC. Now the two HPWCs are on "dedicated branch circuits" and the "site" assigned in the HPWC config is the subpanel. I think this is the "right" way to do it.

 

[ucmndd]

Correct, it does say breakers on individual circuits. But it also shows a schematic for no sub panel and running up to four connectors off of one supply. Hence, my questions. I have not received a call from the electrician yet.

I don't interpret that drawing in the install manual the same way you do. That "one supply" is the main service panel, and each line coming off of it is interpreted by me as its own branch circuit with its own 60A breaker (consistent with the language).