Gen 3 Power Sharing Question (50Amp) Guidance

[ZRG1234]

We recently purchased a 2nd Model 3 and interested in purchasing a 2nd Gen3 Tesla Charger for PowerSharing. I do not want to run a new wire from the basement to garage. My neighbors electrician and will help with install just trying to gather as much info.

• Could I add sub panel to garage with the 6/2 Romex?
• If so, is it a 50Amp Sub Panel then (2) 25Amp double breakers to (2) Gen3 Chargers?
  • or 100Amp Sub panel then (2) 50Amp double breakers to (2) Gen3 Chargers?

Current Environment

• Breaker Panel located in Basement
• 50 Amp Double Pole Breaker (Charging limited to 40Amp)
• 6/2 Romex - Panel to Switch Disconnect located in Garage
• 6/2 Romex - Switch Disconnect to GEN3 Charger located in Garage

 

[Braumin]

You can keep the 50A breaker. You don't need a sub panel for this. If you wanted to run a 100A sub panel and then 2 50 A breakers with one to each unit that would not be using the power share feature. Each would be standalone. 6/2 Romex cannot handle 100 Amp though you would need 1 gauge wire.

If you want to do power share you can keep your 50A breaker and set the leader unit to say there is 50A available. It will then not allow the combination of both chargers to exceed 50A which means actually 40A draw (80% load max).

Tesla has a video on it your electrician can refer to

Load Sharing – Second Generation Wall Connector | Tesla Support

View how to create a load sharing network of second generation Wall Connector.

www.tesla.com

 

[ZRG1234]

This is very helpful. Let me digest the info and may have a followup question. Thank you!

 

[Rocky_H]

You don't need a sub panel for this.

Well, yes you do. The installation parameters for the Gen3 wall connector are that they need a subpanel with each one having its own breaker, so you can't just physically split and fasten the power connection wires directly.

@ZRG1234 But yes, as to the sharing configuration, @Braumin is generally right about how to set that up. You have an existing 50A line to the garage. Put a subpanel on it, and then it can split to two two-pole 50A breakers that go out to your two wall connectors. The configuration in the connectors with sharing should allow either to run at up to 40A if it's the only one active, but keep the total within 40A if they are both running.

 

[davewill]

One thing to note is that since you only have 6/2 Romex, there is no neutral available, as would be expected in a standard subpanel. I'd go with a small "load center" that just has room for 2 or 3 breakers and label it as EV or 240v only, rather than a large subpanel that might be mistaken for a "real" subpanel that general circuits could be run from. You can put it in place of the switch disconnect as the breakers will provide the switch function.

 

[Braumin]

Well, yes you do. The installation parameters for the Gen3 wall connector are that they need a subpanel with each one having its own breaker, so you can't just physically split and fasten the power connection wires directly.

@ZRG1234 But yes, as to the sharing configuration, @Braumin is generally right about how to set that up. You have an existing 50A line to the garage. Put a subpanel on it, and then it can split to two two-pole 50A breakers that go out to your two wall connectors. The configuration in the connectors with sharing should allow either to run at up to 40A if it's the only one active, but keep the total within 40A if they are both running.

The installation guide shows a distribution box, not a sub panel with breakers. Regardless, this will need a permit and such so a licensed electrician would be needed. Code everywhere is likely very specific so always take everything online with that in mind.

 

[Rocky_H]

The installation guide shows a distribution box, not a sub panel with breakers.

The installation guide for the Gen2 shows that you can use a distribution box (junction box). For the Gen3 (installation guide page 32), it shows you have to use individual breakers per unit, so that's a subpanel. They show only two choices: breakers straight from the main panel, or breakers from a subpanel. You can't just use a junction box with the wires split with Polaris connectors. That was allowed on the Gen2, because they all had to be set for the same amp level. With the Gen3 allowing configuration of them at different amp levels, they need to use a breaker for each one to make sure they are matched properly to how they are installed.

https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf

 

[Braumin]

The installation guide for the Gen2 shows that you can use a distribution box (junction box). For the Gen3 (installation guide page 32), it shows you have to use individual breakers per unit, so that's a subpanel. They show only two choices: breakers straight from the main panel, or breakers from a subpanel. You can't just use a junction box with the wires split with Polaris connectors. That was allowed on the Gen2, because they all had to be set for the same amp level. With the Gen3 allowing configuration of them at different amp levels, they need to use a breaker for each one to make sure they are matched properly to how they are installed.

https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf

D'oh! Sorry I was looking at the Gen 2. My bad!

 

[jjrandorin]

You can keep the 50A breaker. You don't need a sub panel for this. If you wanted to run a 100A sub panel and then 2 50 A breakers with one to each unit that would not be using the power share feature. Each would be standalone. 6/2 Romex cannot handle 100 Amp though you would need 1 gauge wire.

If you want to do power share you can keep your 50A breaker and set the leader unit to say there is 50A available. It will then not allow the combination of both chargers to exceed 50A which means actually 40A draw (80% load max).

Tesla has a video on it your electrician can refer to

Load Sharing – Second Generation Wall Connector | Tesla Support

View how to create a load sharing network of second generation Wall Connector.

www.tesla.com

I am pretty sure that the video linked is the Gen 2 wall connector one, and its not really applicable to gen 3s. Gen 3s want a separate breaker for each unit, and do not have communication wires. You will want to look at information specific to Gen 3s.

EDIT: I should have read to the end, this was already covered by @Rocky_H

 

[jjrandorin]

Wall Connector Power Sharing | Tesla Support

With Power Sharing, you can allow up to six 3 Wall Connectors to share power and charge multiple vehicles at once. Learn how to set up and troubleshoot Power Sharing.

www.tesla.com

https://www.tesla.com/sites/default/files/support/charging/Gen3_WallConnector_Installation_Manual.pdf

(page 33 and on, for power sharing)

Gen 3 wall connectors want 1 breaker per wall connector, unlike Gen 2s. Its called out specifically in the above Tesla provided Gen 3 installation manual.

EDIT: I should have read to the end, this was already covered by @Rocky_H

 

[ZRG1234]

Would a panel like this work with (2) 50 Amp Double Pole Breakers?
Main panel has 50Amp circuit

Square D Homeline 100 Amp 6-Space 12-Circuit Outdoor Main Lug Load Center(HOM612L100RBCP) HOM612L100RBCP - The Home Depot

 

[davewill]

Would a panel like this work with (2) 50 Amp Double Pole Breakers?
Main panel has 50Amp circuit

Square D Homeline 100 Amp 6-Space 12-Circuit Outdoor Main Lug Load Center(HOM612L100RBCP) HOM612L100RBCP - The Home Depot

Yes, but I would choose the 70amp 4 circuit version as that's plenty of room for your application.

 

[ZRG1234]

Yes, but I would choose the 70amp 4 circuit version as that's plenty of room for your application.

Perfect, Thank you!

 

[Gauss Guzzler]

I concur with @Rocky_H and @davewill

You can run your 50A breakered 6/2 to a load center full of 50A breakers and supply as many Gen3 chargers as you want with any type of 6 gauge copper. The chargers can all be configured for 40A charge/50A circuit so long as power sharing features are active.

You do need at least 4 spaces (not 4 "circuits") in that subpanel though, so the 100A 6-space model would be good. There are indoor versions as well, either surface or flush mount. And better prices/selections/politics at Lowes:

https://www.lowes.com/search?searchTerm=load+center&refinement=4294556102,4294556095

You have a great plan to split the existing 6/2 circuit like this, assuming the run from your main breaker panel is expensive. Otherwise, consider a whole new 6/2 run directly from the main panel for a less finicky arrangement.