Circuit for Tesla Wall Charger

[jeff48356]

I've never installed one of these before, but I have a customer who may need a Tesla wall charger installed in his garage. It calls for a 60-amp circuit, and the unit is direct-wired. Can I use 6-2 romex, or would 6-3 be required? I can't imagine this would call for 120/240V, so I would like to use 6-2 if possible. Anyone ever install these units before?

 

[wwhitney]

Commercially available residential EVSEs are 240V only, so you only need two circuit conductors. But unless the Tesla EVSE supports a setting of 44A continuous maximum, you can't use 6/2 NM, as it is only rated for 55A. This came up just recently in part of this thread.

Also, it looks like 4/2 NM is not generally available (at least, Southwire doesn't make it). So you could use SEU cable, and depending on which code cycle you are on and whether the circuit would pass through thermal insulation, you can either use #6 SEU cable at its 75C ampacity of 65A, or you need to stick with the 60C ampacity and use #4 SEU cable.

Cheers, Wayne

 

[wrobotronic]

 

[Dennis Alwon]

All the resi units I have wired by Tesla were 50 amps. You sure it is 60 amps? Pipe it and use #6

 

[jeff48356]

Commercially available residential EVSEs are 240V only, so you only need two circuit conductors. But unless the Tesla EVSE supports a setting of 44A continuous maximum, you can't use 6/2 NM, as it is only rated for 55A. This came up just recently in part of this thread.

Also, it looks like 4/2 NM is not generally available (at least, Southwire doesn't make it). So you could use SEU cable, and depending on which code cycle you are on and whether the circuit would pass through thermal insulation, you can either use #6 SEU cable at its 75C ampacity of 65A, or you need to stick with the 60C ampacity and use #4 SEU cable.

Cheers, Wayne

Yes, the unit has several settings, according to the size of the breaker being used. If it's set to 60A, it will draw 48 amps. That is, the 80% continuous allowance is already programmed into the unit. So #6 should be the correct size, since it's rated for 55A.

 

[wwhitney]

This page has info on configuring a Tesla Wall Connector and on the maximum charge rate that different Tesla vehicles can use. If a 60A circuit was requested, it sounds like the owner has or will be getting a Model 3 Long Range or a 75 kWh Model S or Model X and wants to be able to charge as fast as the vehicle can handle.

Cheers, Wayne

 

[Coppersmith]

I've installed several Tesla chargers in garages all of which plugged into a 4-wire 50 amp range receptacle. I mounted the receptacle directly under the panel and piped it in. I used #6 THHN. I have also installed a dedicated EV charging station outside of an office which was a Seimens brand but used on a Tesla. Also piped, 50 amps. That one was three conductor if I remember correctly.

ETA: After reading the info wwhitney provided I now know I was hooking up the mobile connector while you are doing the wall connector.

 

[wwhitney]

The Tesla Mobile Connector is an EVSE that plugs in and maxes out at 40 amps (continuous, so 50 amp circuit). The Tesla Wall Connector is a different model.

Cheers, Wayne

 

[jeff48356]

This page has info on configuring a Tesla Wall Connector and on the maximum charge rate that different Tesla vehicles can use. If a 60A circuit was requested, it sounds like the owner has or will be getting a Model 3 Long Range or a 75 kWh Model S or Model X and wants to be able to charge as fast as the vehicle can handle.

Cheers, Wayne

Exactly! He plans to buy a Tesla Model 3 Long Range vehicle, and the specs call for a 60A breaker. I assume there are only two power conductors and a ground, so I wanted to verify that 6/2 Romex was the type of cable to use.

 

[wwhitney]

Exactly! He plans to buy a Tesla Model 3 Long Range vehicle, and the specs call for a 60A breaker. I assume there are only two power conductors and a ground, so I wanted to verify that 6/2 Romex was the type of cable to use.

The type, but not the size, as mentioned above. With 6/2 Romex, you'd have to set the EVSE to 40 amps, not 48 amps, and use a 50A breaker.

Cheers, Wayne

 

[jeff48356]

The type, but not the size, as mentioned above. With 6/2 Romex, you'd have to set the EVSE to 40 amps, not 48 amps, and use a 50A breaker.

Cheers, Wayne

If I use 3/4" PVC Sch. 40 with #6 black/red THHN conductors and a #10 green, could I use the 60A breaker?

 

[wwhitney]

If I use 3/4" PVC Sch. 40 with #6 black/red THHN conductors and a #10 green, could I use the 60A breaker?

Sure, as Dennis suggested. The 75C ampacity of #6 copper is 65A, so no problem. And the Wall Connector has 75C rated lugs for terminating the branch circuit, per the installation manual.

Cheers, Wayne

 

[LarryFine]

You could also use #2 al SE cable.

 

[wwhitney]

You could also use #2 al SE cable.

Annoyingly, the Tesla Wall Connector manual says "Use only copper conductors."

Cheers, Wayne

 

[jeff48356]

Annoyingly, the Tesla Wall Connector manual says "Use only copper conductors."

Cheers, Wayne

That's good. I don't like aluminum conductors for anything other than service conductors.

 

[readydave8]

Annoyingly, the Tesla Wall Connector manual says "Use only copper conductors."

Cheers, Wayne

So you would run AL to disconnect or junction box, and from there copper to unit?

 

[LarryFine]

So you would run AL to disconnect or junction box, and from there copper to unit?

That would be acceptable, or even a proper al-cu splice in the unit if space permits.

 

[LarryFine]

I just so happens that a customer has requested a Tesla charging installation from me, and I have a few questions. Even though he has no electric car yet, he's asking to have two outlets installed now to save a little bit on labor, despite my advice to go with one for now.

Originally, he asked about two simple 50a circuits and receptacles, but then decided on the Wall Connector instead. I'm getting the impression that, if two circuits are desired, the Wall Connector is a waste of money.

1. Is there any advantage to using a Wall connector over a 50a receptacle? It appears that the Wall Connector allows use of a 60a circuit instead of a 50a circuit. Hardly seems worth the $500 extra.

2. It appears that a single 100a circuit can supply up to four Wall Connectors (with a signal cable interconnection). Must it be a full 100a circuit that is used to supply two (or more) Wall Connectors?

3. Is there any advantage to using a 100a circuit to supply two Wall Connectors as opposed to using two separate 60a circuits? Is cost of one 100a circuit vs. two 60a circuits the only consideration?

4. Both circuits would be run in one conduit in the garage. Which would be more cost-effective, one 100a circuit or two 60a circuits? Would two 50a vs. two 60a circuits equal the caopacity of one 100a?

 

[wwhitney]

The main question is which/how many Teslas your customer is going to get, and what size charger they have in them. Per https://shop.tesla.com/us/en/product/vehicle-accessories/model-s_x_3-wall-connector.html different models can take advantage of a maximum 90A, 60A, or 40A circuit. Although in the last case I don't think those cars are in production yet.

1. Is there any advantage to using a Wall connector over a 50a receptacle?

The main advantage is that you could keep the Tesla Mobile Connector in your car for portable use, or use it to charge a different car from a 2nd circuit. Or if your car can use a 90A circuit, and you run a 90A circuit, the car can charge a lot faster.

2. It appears that a single 100a circuit can supply up to four Wall Connectors (with a signal cable interconnection). Must it be a full 100a circuit that is used to supply two (or more) Wall Connectors?

No, it can be any size, per the manual.

3. Is there any advantage to using a 100a circuit to supply two Wall Connectors as opposed to using two separate 60a circuits? Is cost of one 100a circuit vs. two 60a circuits the only consideration?

The other consideration is that some Teslas can take advantage of up to a 90A circuit, which would only be possible with the larger circuit size.

Cheers, Wayne

 

[GoldDigger]

Finally, note that if you have a 100A circuit available, you can have two wall connectors and either car can draw up to 90A when it is the sole user, while they will automatically coordinate to use a total of 100A when both are charging.
With two 60A receptacles attached to the same 100A circuit no car can take more than 60A at any time and if two cars are charging simultaneously it could overload your 100A circuit.
The question remains whether it is worth the extra $500 per connector.