My wall connector has arrived in anticipation of my Model 3. I have a friend who is an electrician providing some advice when getting quotes for the install. He states the difference in material cost is minor for higher amperage circuits and planning ahead on the circuit size is a good idea. He isn't familiar with the details on how multiple WC's work, however.
The Model 3 LR will charge at a max of 48 amps which would require a 60a circuit. There's a good probability we'll end up with a second Tesla at some point and utilizing two wall connectors with the communication link would be ideal. With this in mind, would it be logical to install an 100a charging circuit now to the single WC? Clearly, a single wall connector would use roughly half of that, but adding a second connector in the future would avoid redoing the original install to handle the higher current.
Short of the higher gauge wire, different breaker, and an external power switch to the circuit, the cost of the labor would be similar.
Am I approaching this the right way? Those that have installed second Wall Connectors, did you have to redo the original install or did you run a totally different circuit to the 2nd WC?
I don't want to overdo a straightforward install, but I don't want to pay again to upgrade the first connector's install... assuming I'm understanding this all correctly.
Your friend is correct. The "trip charge" and labor will be relatively similar, though larger wire will be harder to work with and add a bit of time.
So the 100a vs 60a breaker will be more expensive, the wire will be larger (6awg in conduit is fine fo 60a, but your need #3 awg for 100a - both copper of course). If NM (Romex) you need #4 for 60a (will actually handle 70a). #2 NM will only do up to 95a (so really 90a setting on HPWC). I would recommend conduit for these higher amperage circuits. I think #2 is the absolute max size that can fit under the HPWC terminals. With larger wire you may require larger conduit. So yeah, 100a will be more expensive, but if you are planning for a second Tesla it is a great solution. The sharing ability of the HPWC's is awesome. Model S and X units can (when equipped) draw up to 72a each so most folks don't have 180 amps of extra "service" capacity laying around (to give each S or X a dedicated 72a), but the ability to share one circuit is fantastic since often only one car will need the capacity, but you don't necessarily know which. You can charge both at 40a to start, but then when one finishes the other can ramp up to 72....
I would probably run the wire from the panel to a junction box and then coil/fold some extra wire in there for the initial install. Then later when you go to add the second unit, cut the wire (or just strip off some insulation) and use like split lugs to connect in the new run and insulate it well with electrical tape (and there is another type of tape I think they use for this).
We need to talk about if your main electrical service can handle 100a though. What size electrical service do you have? You will need to do a load calculation (or have one done) to figure out what you have capacity for. If you post pictures of your meter base and all your panels we can help you figure it out (even with covers off the panels if you are able to do that safely).
What I love about the wall connector is that you can install it on any size circuit basically up to a 100a circuit, but then you can just crank down the max amount it will let the car(s) have using the rotary dial. Whatever you have it set to is what the NEC nameplate rating is that is used in the load calcs. So if you end up doing calc's and realize you can only do 70a of capacity (56a continuous) then you can just set the wall connector to that even though you over-provisioned it on a 100a breaker and wire. But then say later you replace the oven with a gas one, you can just go crank up the wall connector and get a full 100a perhaps.
Put the 100a breaker with #2,or #3 wire , dial down the amps in the WC to 48a ..in the future u can add second WC and set for load sharing
As others mentioned, there is zero reason to dial the amps down unless you need to fit into a certain amperage to avoid violating the load calculations.
#2 copper is the largest conductor you can put under the Wall Connector terminals per Tesla support.
Also, on the comment about needing a switch (disconnect), here is exactly what NEC 625.43 says about EVSE disconnects:
Here is a definition of Readily Accessible, though it references 2014 code:
Readily Accessible | Electrical Contractor Magazine
"The NEC’s definition of readily accessible states: “capable of being reached quickly for operation, renewal, or inspections without requiring those to whom ready access is requisite to actions such as to use tools, to climb over or remove obstacles, or to resort to portable ladders and so forth.” The underlined text is new for the 2014 NEC but not new for anyone working on or installing electrical equipment, because the requirement for “no tool access” for certain equipment installations has long been a rule that everyone understood, even if the “no tool rule” wasn’t previously in the definition.
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So my take on this is that if you install a circuit that is *over* 60a then you need a "readily accessible" disconnect that can be locked in the off position. I believe most AHJ's are fine with this just being a little piece of metal on the breaker panel cover that lets you lock the breaker off. In most cases, I do not believe it even has to be within line of sight or anything. An EVSE nearly never needs taking out of service... Not much to work on (unlike HVAC gear, dishwashers, etc...) The ability to lock it in the off position makes a lot of sense to me, but I don't see an issue with the breaker panel being in a different part of the house. Anyone coming to work on an EVSE probably has access to the whole house. HVAC tech's often (at least in commercial) only have access to the roof, etc, so a local disconnect is critical.
I have heard once that one AHJ wanted the disconnect very close to the EVSE (within sight), but only once.
Also note that 240v residential service does not have either leg more than 150v to ground so that portion of the clause does not drive the requirement. That would kick in on 277v feeds off 480v three phase service.
