Any drawback to future proofing a single Tesla wall connector with 100 amp circuit?

[Zaxxon]

To be clear, this is if you have other EVs besides a Tesla?

Yes.

 

[jerry33]

FWIW, on our 200 amp panel, we have one S and one Leaf. The S charges on a 14-50 at 33 amps (50 amp circuit) and the Leaf charges from a Clipper Creek at 32 amps. Both cars charge at the same time and both are fully charged in the morning.

 

[Antares Nebula]

Yep. And FWIW, in my case I've got 200A service to the house, solar PV on the roof, and will have one 60A circuit to the garage sharing between 2 HPWC (being installed later this week). That's the max that the load calc will allow in my scenario. I'm on TOU where I'll only ever really charge between 9p-9a. And I'm sure it'll be fine with my 100D X and LR 3. 11.5 kW charge power = 10.3 kW net of charging losses (conservatively) still gives me ~125 kWh charging capacity each evening. The cars combined only have ~175 kWh capacity, so unless they both roll in at 10% charge and want 90% on the same evening, I'll never see them fail to both fill up overnight.

Interesting. How do you determine your max available load capacity for the HPWC(s). Does the electrician do this? Or do you have to calculate it based on your panel capacity, and then estimating the electrical draw on all the appliances in your house (which can be very onerous I imagine)?

I mean if you tell the electrician to run a 100A line, will he just do it? And then you end up blowing all the breakers in your house?

(This is getting more and more complex! )

 

[Zaxxon]

Interesting. How do you determine your max available load capacity for the HPWC(s). Does the electrician do this? Or do you have to calculate it based on your panel capacity, and then estimating the electrical draw on all the appliances in your house (which can be very onerous I imagine)?

Whenever you make a change in your home's panel, the electrician (or you, if you're doing it yourself) is supposed to do a load calculation. The load calc is a (semi) standard calculation of your panel's capacity and expected load for your home's particular usage that ensures that your home as a whole will never try to pull more than its rated load.

I mean if you tell the electrician to run a 100A line, will he just do it? And then you end up blowing all the breakers in your house?

No, he won't if he's competent. This is why the load calc is done--to ensure that it's highly unlikely that the change you're requesting will blow your main breaker. In my case, the load calc shows that with a 60A breaker to the garage (being upgraded from its current 50A supporting a 14-50, which is getting replaced with 2 HPWC), my home's calculated max is now 191A. Which is why I can't go higher than 60A in this upgrade, as it'd put me over the 'safe' level.

The calc is likely being conservative, as I only really charge at night. It's unlikely, for example, that I'll ever have the PV producing at max while I'm charging at max, while the AC is on high, while the washer, dryer, dishwasher, and oven/range are all on high. But since I don't actually need more than this 60A circuit and the current wiring from panel in my backyard to my garage is only of a gauge to support 60A anyway, I'm not pushing for more.

 

[Antares Nebula]

Okay. Whew! Thanks! Very helpful.

 

[Daniellane]

Hey folks, @Daniellane, @Runt8, and everyone else, I want to go back to an earlier question, which is still not clear to me.

On Tesla's support page, Wall Connector
it says:

"Higher amperage installations are recommended (but not required) when power sharing to maximize the amount of power split between each car when charging."

So why can't the circuit breaker be set at say 120A on a 150A circuit (if you have the capacity), with two wall connectors? (And set the rotary switch on each wall connector to 48A.) So that each can draw the max 48A, when charging two model 3s at the same time. Would this work?

From what I understand, the intelligent sharing via the master/slave/slave setup is only if you don't have the circuit capacity (say max of 50, 80 or 100A), which most people probably don't (as @eprosenx and @Zaxxon pointed out). That way, you can get max charging with single car, but lower speeds if you need to charge more than one car. Also you can take advantage of older Model S,X charge speeds (on say a 100A line).

But (at least as a theoretical exercise) if you only have model 3s or the newer 48A max charging S or Xs, AND also have the capacity for a 150A line (120A breaker), then you can run one shared line or two separate 75A lines (w/ 60A breakers) for two wall connectors (the shared line being cheaper parts and labor wise I would guess). In either scenario, you get the max charge speed. No?

Sorry for all the questions, just trying to understand what the theoretical limits are here.

Thanks!

So, first, going back to you’re original question on “future” proofing. If only we knew what the “future’ was going to be?
So, for me, my “future” proofing was narrowed down to my hopes in becoming an all-Tesla family. For you, it might be different.
I’d consider a sub-panel as high amp as possible centrally located to potential Charger/outlet installations, and then you can expand fro there.
That said, when planning our setup, which was up and running prior to taking delivery of each car respectively, I had a number of phone conversations & email exchanges with one of the experts in Tesla’s Charging Group. Immensely helpful. If you’re planning to do something out of the ordinary, I recommend you contact Tesla directly, at least for additional assurance your plan is optimal.
I’ll look for the phone # get it to you.

 

[Daniellane]

So, first, going back to you’re original question on “future” proofing. If only we knew what the “future’ was going to be?
So, for me, my “future” proofing was narrowed down to my hopes in becoming an all-Tesla family. For you, it might be different.
I’d consider a sub-panel as high amp as possible centrally located to potential Charger/outlet installations, and then you can expand fro there.
That said, when planning our setup, which was up and running prior to taking delivery of each car respectively, I had a number of phone conversations & email exchanges with one of the experts in Tesla’s Charging Group. Immensely helpful. If you’re planning to do something out of the ordinary, I recommend you contact Tesla directly, at least for additional assurance your plan is optimal.
I’ll look for the phone # get it to you.

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[Antares Nebula]

@Daniellane Thank you! Very helpful.