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Wall Connector install - Planning ahead

Discussion in 'Model 3: Battery & Charging' started by NathanielHrnblwr, Aug 11, 2018.

  1. NathanielHrnblwr

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    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.
     
  2. P85_DA

    P85_DA Supporting Member

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    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
     
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  3. jelly

    jelly Member

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    Yes I did this. Fortunately SCE offers a dedicated EV line, so I did not have to upgrade my old panel to accommodate my car. My old panel is only 100a service.

    Instead, I installed a new line (metered at the Ev rate) to its own 100a panel and ran a 100a circuit. Same as you, I can now add a second HPWC in the future.
     
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  4. Rockster

    Rockster Active Member

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    You’re thinking correctly. If you’re eventually going to have two wall chargers then 100 amp is the way to go. I did this, and then, when I got my second Tesla, I split the 100 amp line using multi tap connectors, added a second wall charger,* and let the load sharing protocol handle charging two cars at once.

    BTW, when you are running just the first charger on the 100 amp line there’s no reason to dial down the amperage within the charger itself because you control the amperage drawn with a setting in the car. The wall charger setting controls the max amperage that the charger is allowed to take, not what you expect to send to the car.


    *I actually replaced the first wall charger when I bought the second one because my original was a gen 1 without the load sharing ability.
     
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  5. NathanielHrnblwr

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    Great, thanks everyone for the confirmation. Glad that I'm approaching this the best way.
     
  6. eprosenx

    eprosenx Member

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    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.

    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:

    Screen Shot 2018-08-11 at 10.35.35 PM.png

    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.
"

    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.
     
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  7. rdlink

    rdlink Member

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    Curious. Did SCE charge you and setup fee for the dedicated run? If not, that's a great service.
     
  8. Skione65

    Skione65 Member

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    ^^^This is exactly what I’m doing to future proof to some degree. I’m just going round and round on what is the best way to do it. I know I’m putting in a dual pole 100A breaker on #3 or #2 AWG wire off my Main Panel (200A Service) which is in the basement. The run will go about 50’ from the basement through the wall into my 2 car garage and across both bays to my 3.
    I’ve been going around about this “disconnect switch in line of sight readily accessible” business. My Main is in the basement and the garage upstairs. Now I have 2 GE 100A Disconnect Boxes (Switches) standing by for the install, one fused and the other non-fused because I wasn’t sure which was better, to deal with this “readily accessible line of sight” NEC code. Just can’t figure out if it’s better to wire a sub panel in the garage off the main with a 100A breaker in it then to the Wall Charger through cinduit in the garage and use that (breaker in the Main) as the so called “disconnect”. Or skip the sub and just wire off the main thru conduit in the garage to a 100A disconnect then to the Wall Charger (least desirable because those disconnect switches are an eyesore) next to the WC.
    Or as you say @eprosenx, disconnect switch may not be required in the garage just put a lockable plate on the basement breaker though not “line of sight”. Electricians coming tomorrow to finish up a basement remod and I’ll ask him what our jurisdictions code is on that. Going to get him to do the install as an add on to the basement remod/finish.
    I’d LOVE to just have him run the #3 or #2 off a 100A breaker in the Main through conduit in the garage directly to the WC with just a lockout plate on the breaker in the main if doable per code.
    My other question is reliability of the Wall Charger. Great from what I understand but also battling whether to run a separate #6AWG on a 60A breaker in the Main to a Nema 14-50 in the garage as a backup if the WC ever goes down or needs maintenance, then I’d have a way to still charge. It’s my understanding that the Nema if I go that route as an addition needs a neutral in addition to the ground however the WC just needs the ground, no neutral correct (due to it being 240) correct? Also if I do the Nema can the wiring be run in the same conduit as the WC or separate? I know you HAVE to run the #2 Gauge for the WC of you do this as opposed to the #3 in my research.

    Any recommendations or advice would be greatly appreciated from anyone that has gone this route.

    Ski
     
  9. alpinebum1

    alpinebum1 Member

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    I had an existing 50amp NEMA 14-50 in my garage. I had an electrician put in a small breaker panel to terminate the circuit (and provide a switch). I’m finishing the garage and did not want to have to ever run more wire or tear up the drywall. The electrician was concerned that leaving unused wire in the wall, setup per the multi-HPWC diagram, would cause issues with the inspector. I ended up just buying a second HPWC and completing the setup even though I only need 1 at the moment. Also, the shielded twisted (18awg) data link cable was not easy to find. I had to order it online. Good luck!
     
  10. SSedan

    SSedan Member

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    At my local Home Depot #3 Copper is $1.02 a foot #8 for ground is I think $0.56 100amp breaker was $30 more than a 50amp.

    The common worry about material cost difference is IMO misguided, what cost more is going back and redoing it because you "saved" $100-150 on the front end and I really think $150 difference will easily cover disconnect, and other material upgrades.
     
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  11. Skione65

    Skione65 Member

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    @SSedan,

    Yes...same exact pricing here at my HD. The non-fused disconnect was $112 and the fused was $86 I believe. All the wiring I priced is exactly as you quite above. Agree with everything you state.

    Ski
     
  12. jelly

    jelly Member

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    They do not charge for the meter and run. Per the site they say it's built into the time of use rate (13c/kwh 9p to noon, which in socal is decent). Have to pay for the panel install (after it is inspected then SCE installs the meter on it and the run).

    This also qualifies you for $1500 rebate for a level 2 install with a dedicated EV time of use meter.

    Labor and panel/conduit for me was $2,000 plus the HPWC $500. Minus the $1,500 rebate. Net $1,000.
     
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  13. NathanielHrnblwr

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    Great info in here!

    @eprosenx I have 200 amp service to the house. Attached is a pic of the panel. The off breakers aren't used (They had to rearrange my entire panel when solar was installed due to some new code about shared neutrals. previous to solar install, I had something like 6 open breaker slots, now 0).

    My HPWC install is going to be on the interior wall almost directly behind the panel. The AHJ will likely require a disconnect near the HPWC on the same wall so I'm just planning to put it in instead of dealing with the hassle of inquiring.
     

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  14. eprosenx

    eprosenx Member

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    Please post a pic of the door of the panel also. Should have a sticker on it with panel info which among other things tells us where tandems are allowed to be installed.

    If you can do it safely, a pic with the cover off would be great as well.
     
  15. eprosenx

    eprosenx Member

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    If you are going to go with a disconnect switch, I would do the non-fused one since I don't see a value in having two overcurrent protective devices in the same branch circuit. More places for things to fail and to have to troubleshoot...

    The subpanel vs. disconnect in the garage is an interesting discussion. Again, I am really not convinced of the value of having a disconnect for EVSE's in "line of sight" (I do not believe this is what the NEC was intending to require). But if you must have it due to your local AHJ, that does bring up a good question of if using a subpanel to achieve that makes sense. I mean, it is weird to have a 100a circuit from the main panel feeding a panel with a 100a branch circuit, but whatever...

    One interesting option might be to install a subpanel in the garage using Aluminum wire as the feeder (which should be much less expensive). You could potentially install like a 125a breaker (typically the largest allowed in a regular breaker position for most manufacturers). Use SER wire of 2/0 (or maybe even 1/0, though it is only rated to 120 amps - though the next size up rule might apply there?). That might kill a few birds with one stone: It would allow the long run to be in aluminum wire and then the short run to the HPWC to be copper (which is required for the HPWC), and it provides the disconnect, and it gives you flexibility to later add say a non-Tesla charger. Oh, and the SER wire does not to be run in conduit if it is in the walls or maybe even exposed in some limited access situations? One thing I have thought of is actually wiring the second HPWC to its own 100a breaker off the subpanel later (so I did not have to muck with trying to use split bolts and a junction box to split the wire) but STILL wire the HPWC's together as a team so they never in aggregate drew more than 80 amps (or whatever you set them to). You are paying for another 100a breaker, but not having to pay for the junction box and split bolts and whatever tape wrapping needed to be done... Then you have this subpanel in the garage that you can later do whatever with...

    To your point about backup charging, you could wire something off that subpanel and use the "non coincident loads" clause to argue it should not factor into the power calculation. A 14-50 would be stupid cheap to install right below the subpanel (also, as an emergency backup even a 20a 240v receptacle might be sufficient).

    To your comment about wires in conduit: You can run multiple sets of wires in one conduit, but once you have more than three "current carrying conductors" (excludes grounds and normally neutrals also) then you may have to derate those wires. The subpanel may become a better option. Often times I don't think this results in any actual deration of the wire as I think you do this deration off the 90c rating of the wire (assuming it is so rated) but the wire was already limited by the 75c rating of the terminals on either end so having say four current carrying wires in one conduit often does not result in any net loss in capacity (or at least does not require upsizing the wire).

    So does this mean you have a 50a breaker in your main panel which runs to a subpanel (with no main breaker, just lugs) and then out of that panel is one or two 50a circuits feeding to two HPWC units that are electronically linked and told to never draw more than 50a (well, really 40a?). So does that mean your feed to that 50a panel in the garage is like #6 AWG NM (romex)? If so- This is a totally workable situation. ;-)

    To my comment above, I am not sure I would want to use a fused disconnect, just more to deal with. Funny that it costs more for the non-fused one. Probably because every AC unit in the US needs the fused version, so that is very commodity.

    That is VERY odd that installing solar would result in having six less breaker spots? Usually solar only needs a single two position slot. Are you saying that they were correcting dangerous deficiencies of the previous panel install? Normally just adding something like solar I don't think means you have to bring everything up to current day code (if so, you would have to install all AFCI breakers, etc...) The only changes made to "multiwire branch circuits" lately that I know of might be requirements to have combined shutoff handles so both are turned off at the same time (not necessarily combined trip, but combined shutoff). But I would not have thought they would make you add this due to just adding solar. Or maybe a previous installer had installed multiwire branch circuits on the same phase legs for both common neutral circuits which is hazardous? Though this can normally be rectified by just moving some stuff around (without taking more breaker positions up).

    I will look at your picture in a bit and provide feedback. I need more details on that panel to really understand what is going on there.
     
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  16. P85_DA

    P85_DA Supporting Member

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    I have similar setup as OP back to back ..no disconnect I passed inspection fine ...as the breaker was close enough (other side of wall )
     
  17. NathanielHrnblwr

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    The solar installer stated they had to update the panel to current code when doing the install. My memory may not be entirely correct, but I believe it had to do with circuits sharing a neutral. This was ok when my house was built in 05, but in 2017 it isn't. Most municipalities apparently aren't sticklers about it, but my city specifically apparently is. They weren't happy about doing it but did it nonetheless to pass inspection. Doing the update used up more space in the panel due to Square D only making breakers that have the bar in the inner two switches.. or something.

    Now that I look at it, there were 4 unused breakers post solar install. You can see three of them remaining unused and turned off in the pic. Those used to be at the bottom, along with the space the solar sub panel eventually used.
     
  18. eprosenx

    eprosenx Member

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    Some first thoughts (need those added pictures to say more):

    I am not sure how you are getting away with a 60a solar feed in breaker. I need to go read those code sections, but typically you are not allowed to load the bus to more than 120% of its rating (this is a special allowance for solar feed-in). So that means no more than a 40a solar breaker on a 200a rated panel. (maybe your bus is rated to 225a or something even though the main is only 200a? - need to see the specs)

    I am curious which breaker positions in this panel are allowed to have tandems installed. Typically you can't have more than 42 breaker poles in a panel, so two are for the "main" I think, that leaves 40 possible. You have a 30 spot panel, so typically, 20 of them will only allow regular breakers, and 10 of them will allow tandems. This all makes sense until I see a tandem in position 20. Curious how that is allowed.

    42 Circuit Rule in Electrical Panels (PanelBoards/Load Centers), Wenatchee Home Inspections | NCW Home Inspections, LLC

    FWIW, I installed my solar on a tandem, not sure if that was allowed or not, but the inspector passed me (maybe he just wanted to get off early on a Friday before a three day weekend). Though I think the max size tandems I have seen are 50a.

    I am curious why you have two 240v breakers labeled for lights? Do you have 240v lights in a residence??? Oh wait, or are those the multi-wire branch circuits that they somehow made you bring up to modern requirements of having a single shut off switch?

    Also, GDO- Is that Garage Door Opener? Is that 240v? If so, is that some massive door or what? ;-) Or just more multi-wire branch circuits?

    And what is the "fan"? Is that an air handler for HVAC? Or a whole house fan? Or two fans for the two HVAC units but again on a multiwire branch circuit? (for the record, I hate multiwire branch circuits - when I build my next house I won't let any be installed - they just have some annoying limitations)
     
  19. NathanielHrnblwr

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    Yes, it's a 225 bus. That was something they needed to validate prior to the solar install.

    I'm not comfortable opening up the panel but I did take a pic of the inside of the door. Please ignore some of the black marker labels - those were there prior to the reorganization of the panel. Some aren't correct anymore. I've been labeling things as I go with the labeler. Yes, that's a garage door opener circuit but it is only the top switch. Those two circuits have a shared neutral and had to be tied together like that due to updated code. Fan is FAU. Red one is correct. 2x FAU's.

    Fortunately, the electrician will sort out the details. I expect a sub panel to be installed and move some of the accessory circuits to it. Will be a good way to isolate circuits for the eventual Powerwall. :)
     

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  20. eprosenx

    eprosenx Member

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    Gotcha, yeah, so looks like that solar breaker is ok. How big is your array? My breaker is only 15a for my solar! Yours must be huge! ;-) (I am wondering if yours could fit on a 50a breaker which might allow the use of a quad tandem in that spot since that is two of the ten spots that are allowed for tandems - it looks like they only make up to 50a ones - I do need to check if solar backfeed is allowed on quad tandems)

    It does appear that there should not be a tandem in spot 20. I am curious how someone managed to get that in there without defeating the rejection tab.

    For installing a HPWC or a subpanel in the garage you could probably do it with that existing panel, you just may need to move some more circuits around. You could move the ones in position 20 to the two empty 15's, and then one of the 20's off position 21 (swap position 21 for a 20/15 split breaker) into the empty spot on 25, then put the 15 in slot 18 into the new 15a position on 21. That gives you position 20 and 18 to put a large capacity 240v breaker for the HPWC/subpanel. ;-)

    But of course you need to run some load calculations to see what you have available per the math.
     

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