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New Wall Connector :)

Discussion in 'Supercharging & Charging Infrastructure' started by pluginx007, Apr 12, 2016.

  1. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    If you use one breaker, that's the max charging current both of them get together. If you can go with 2 breakers, do it -- but a lot of homes don't have the ability to do it in their service load calcs and/or budget for wiring runs back to the service panel.

    This gives you more options.
     
  2. Rocky_H

    Rocky_H Active Member

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    Well, it’s certainly not “very clear”. You are going by pictures in an installation manual for a unit no one has physically gotten yet. They talk about sharing on one circuit, but then they refer to picking a breaker, singular. It should be able to run on a pass-through system, but if that’s not how it is set up, then they need to specify that it needs to use an upstream junction box, with a main breaker in the panel and then additional breakers, one per wall connector, matched to the breaker size of the feeder line, etc. They just frustratingly do not address how to connect the power lines AT ALL in the “daisy chain” master/slave configuration. Since that is a new feature of this unit, you would think that would be something very important to describe.
     
  3. MP3Mike

    MP3Mike Well-Known Member

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    Assuming you have only have 100A of capacity available, would you save any money by using a 100A feeder and sub-panel, vs. running 4 100A feeds from the panel? (How much does the sub-panel parts/install cost compare?) Assuming of course that the inspector would sign-off on the non-concurrent use issue for the 4) 100A feeds.

    I think it makes perfect sense and fits with the announcement that Tesla made about quadrupling the destination chargers. I suspect now instead of supplying two HPWCs and basic installation they will supply 4 and then installation would either be on one or two 100A circuits depending on what the business had available and wanted to supply. (Or of they wanted to set them up in two different locations.)

    Of course then the destination chargers will be like Supercharging in that they are paired, and you have to figure out which slot to take to get the fastest charge.
     
  4. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    It tells you how to install a singular unit, which is to install it on a branch circuit. There is no mention of any pass-through whatsoever in the manual -- some are reading "pass-through" into it. It's just load-sharing across the units.

    I've got some posts out on various forums where I'm asking a technical question of some inspectors/AHJ's. NEC 210.17 might require each unit be on its own branch circuit anyway - with taps not allowed for daisy chaining -- but you can still save a lot of money by making only a single 100A run back to your service panel. This means that you would still need 4 individual 100A circuits from a subpanel located in the garage, but the feeder back to your service panel could be a 100A feeder with a 100A breaker instead of needing to size it for 400A.

    Assume for a minute that your service panel is roughly 70 feet from the center point of your 4-car garage where you'd install the WC's and then you'd need 5 feet down to each HPWC from there. #2 THHN runs about $1.25 a foot retail right now, and you need 2 conductors (plus let's just assume $0.50 a foot for conduit/fittings and $0.50/foot for your ground wire - it's rough for example purposes). So for a single 100A run, we're looking at $3.50/foot.

    4 individual runs back to your service panel (assuming that you have room for 4 100A breakers) will be 75 feet * 4 * $3.50 = $1,050 for wire alone. Assuming you live in an area where you need disconnects, you'd probably pay about $50 for an enclosure + $40 for a breaker for a disconnect and you're looking at $1,050+$360 = $1,410 parts.

    A single feeder @ 70 feet back to your service panel will be 70 feet * $3.50 = $245. A 100A square D HOM panel with 8 spaces will cost you about $60 with ground bar, plus you'd need 4 breakers (that double as your disconnects) @ $40 ea, so 60+(4*40) = $220. Then you'd need 4 runs of 5' feet avg down to each HPWC or $3.50 * 4 * 5. So $245+$220+70, or $535. That's about 40% of the cost of running 4 independent circuits.

    I didn't include the labor or swearing surcharges for having to drill multiple holes through joists and walls and stuff. :)

    Note that you won't really see these savings if your service panel is mounted in your garage wall and you can just come out the back side -- but that's not always the case. I can also pretty much guarantee that very few houses -- even those with 600A service -- would pass load calculations for an additional 400A.
     
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  5. MP3Mike

    MP3Mike Well-Known Member

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    Thank you very much for the detailed cost estimates.

    It looks like you left the breaker(s) in the service panel out of both estimates, so we could up the costs to $1,570 and $575 respectively.

    Could you not save some by running all 4 100A feeds through one larger conduit, or is that not allowed or would actually cost more?

    I'm not sure I understand what you are saying here. Can you explain some more about this?
     
  6. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Ah yes, that'll just be a difference of 1 breaker vs. 3 - savings of $120 for the subpanel with single-feeder approach.

    When you do that you have to de-rate the conductors. 4 circuits would be 8 current-carrying conductors. 310.15(B)(3)(a) says that when we have 8 current-carrying conductors in the same raceway that we need to derate conductors to 70%. That means we'd need conductors for a 100A load rating to be rated for 142.9A - which means jumping to #1/0 (one-aught) wire.

    Retail for that is about $2/foot per conductor, compared to $1.25. You'll need a MUCH bigger conduit to pull 8 1/0's (my calculator is telling me you'll need a 2 1/2" conduit vs. 4 1" conduits)... but consider that you'll need $6 more per foot for all 4 circuits (8 * $0.75) for a savings of $1.50 per foot in removing 3 of the conduits, and that's not even considering the higher cost of 2 1/2" conduit and fittings on the fourth. And the swear surcharge for connecting a 2 1/2" conduit into boxes, then manipulating 8 different 1/0 conductors? Gonna be high! :)

    I made an assumption that the center of your garage door bays is 70' from your service panel. But if your service panel is either in your garage wall, or on the other side of it, and one HPWC has no run to make at all, you're going to see less of a savings by doing the consolidation. The longer the average distance between your garage door bays and your service panel, the greater the savings.
     
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  7. Cyclone

    Cyclone Cyclonic Member ((.oO))

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    Personally, I feel Tesla will be using this in the destination program to install 2-4 HPWCs wired to 1-2 100 amp circuits and banking that "most" of the time, a 48 amp max car will be plugging in. Couple that with SOC differences, and the chances that either vehicle is artificially limited are lessened. At scale, this is much cheaper overall and helps either Tesla (if paying installation) or the business hosting the destination chargers (if they are paying for it). Either way, I think it will be quite popular.
     
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  8. Skotty

    Skotty 2014 S P85 | 2020 3 LR AWD

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    But I like winding my cord around the unit in a clockwise direction. The new units are not compatible with that. Will they be coming out with a clockwise winding model?

    No, I'm not being serious. But I do like to wind my cord clockwise. :p
     
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  9. MITE46

    MITE46 Member

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    daisy chaining is going to be a game changer...I'm assuming they already got this UL approved...if so that is a steal for $500!
     
  10. fderheide

    fderheide Member

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    I thought I read the instructions call for metal conduit. If I plan to run 3awg (red, black, green) on a 60amp breaker, will the 1" non metallic s40 nema TC-2 pvc rated at 90 degrees be appropriate? My run is about 100ft from basement to garage wall with 80" of the run along the garage ceiling. Plan to charge an X at 48amps.

    Or is there a reason for the metal conduit?

    Am I missing anything else?
     
  11. scaesare

    scaesare Well-Known Member

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  12. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    #112 FlasherZ, Apr 14, 2016
    Last edited: Apr 14, 2016
    I missed that when I was reading over the manual. I have a message into Tesla -- I don't think there's any reason why rigid non-metallic (sch 80 electrical PVC) or flex non-metallic wouldn't be safe. My two HPWC's (older models) are fed with sch 80 electrical PVC and operate just fine. This is the first time I'm seeing a demand for metal conduit.

    Technically, if you install one of these new ones with PVC, as written it would be a violation (because you are supposed to follow manufacturer's instructions). But I can't see a safety problem and I don't know why they demand it. (Solar PV has a requirement for metal conduit only when running inside the home, but that's because of the nature of solar PV systems where the conduit generally carries wires prior to first disconnection opportunity at the DC disconnect.)

    If you're using a 60A breaker, you don't need to use #3 unless you're just preparing for the future. #6 will provide you with enough for the 60A rating. Your ground (green) only needs to be #8 if you're preparing for 100A, or #10 if you're sticking with 60A rating.

    Also note that while 3x #3 conductors in a 1" raceway is legal from a fill perspective, it can be tight and/or difficult from a pulling perspective especially through turns. But if you size your ground appropriately, then you won't have to worry about it.
     
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  13. fderheide

    fderheide Member

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  14. fderheide

    fderheide Member

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    It's in page 11 under installation considerations. Says conduit must be metal and flame retardant.

    You say pvc 80. I got the 40. Should I return it?

    I got the 3awg because that's what the old one called for with a minimum of 4awg for ground. I realize it's too much. Wasn't considering how difficult it would be to pull.

    Trying to keep the formula simple. Thanks for any advice.
     
  15. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    No worries... no need to return the 40 - as long as it's electrical conduit (gray). White water pipe PVC isn't listed for electrical.

    #3 AWG is only needed for 100A installations - so it's a bit overkill, but at least it'll future proof you if you ever want to upgrade to the 100A setting.
     
  16. CmdrThor

    CmdrThor Active Member

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    Tesla has also stated that they are open to other manufacturers using the Tesla plug and getting access to the Supercharger network, as long as that manufacturer was willing to contribute towards the costs of the Supercharger network (and now destination charging network). Tesla has changed the game coming out with an 80A daisy chain EVSE for $550. That is unheard of. You can barely get a 30A EVSE for $550. Tesla is basically showing that their connector is superior and is attempting to make J1772 obsolete. I hope they succeed.
     
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  17. Ulmo

    Ulmo Active Member

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    #117 Ulmo, Apr 15, 2016
    Last edited: Apr 15, 2016
    Just brainstorming here ... specifics of each house and parking spot will blow my generalizations out of the water and will be pertinent in EVERY case, but sort of generally speaking:

    I sort of think the "sweet spot" for this new slavable wall connector is either <=100A or >=200A, with the range >100A and <200A being the less-than-sweet spot. (Fair warning: maybe I'm completely wrong because I haven't fully thought this through, and installers and owners will quickly make my brainstorming about the "sweet spot" ranges moot and useless.) While mulling that over just now, I thought one simplistic perhaps dumb perhaps sometimes sub-optimal way to approach that would be to round down or up to the nearest, and behave that way, such that if you have 120A, just slave them for a 100A and throw away the extra 20A capacity, or if you have 180A, just set them both up as 90A (or whatever is just under that) and forgo the slaving. If you are closer to the middle of >100A <200A, then you have to figure out your most stringent use patterns. Hopefully, this will be a house with a commute under 1 hour, and it will hardly matter, since that is almost never a problem, but you kind of have to take your worst days of the month as the design cases. Like, if I had 150A available, and my commute was 2 hours, then what would I do for two cars? For 3 Tesla home, that's easy: master+slave both share 100A, and dedicate 50A to one more. But for only 2 Tesla home? I'd lean toward independent 100A and 50A, and the person who gets home first always gets on the 50A so the late comer has ability to get ready for work faster.

    Ok, I think I answered my own questions. 120A -- just round down to 100A and let the slaving work its charms (usually easiest option). Anything above, and dedicate 100A to one (or multiple slavable units if >2 Teslas per home/place), and the rest (total minus 100A) to another wall connector. Whoever gets there first gets the slowest charger (unless they got home really early for shower and are going on errands right away, to free up that fast charger spot). Alternatively, if they get home first and people in the household get along and have each others' keys, the first one can fast charge and then the second one can unplug them (or move them to the slow charger) and take over in the fast charge spot. If 3 Teslas in a 150A home with one 100A circuit with two slavable wall connectors and one 50A circuit with one wall connector, first person home gets on the 50A, and the rest of the people get on the 100A. This can be adjusted for the first person who gets home super early getting on the 100A IF and only if they get off it quickly (to do errands), leaving the 100A for the late comers. Possibly, the 100A can be the go-to for everyone all the time, but every evening, anybody plugged into the 100A if not everyone is home yet has to go unplug. "Oh, he's coming home late again -- unplug!" You'd have to have a spare key dongle for the 100A charger for the early comers so the late comer can unplug their cars.

    ==========

    Future design wishes from Tesla: In a more ideal situation, a new upgraded Tesla wall connector could be designed and released that could be programmed with a different maximum total load draw for all connectors than the independent load draws. This would be a specialized master controller that would have an additional setting knob which set the "total maximum load" to above 100A (it could literally be anything up to the number of slaved units times 100A), and specialized slaves that can be set to their respective maximum breaker loads (even if 100A was the assumption, that wouldn't be the end of the world since we're already talking above 100A totals here, but it would be nice if some circuits could be lower than 100A for max flexibility). If they ever software-unlimited the slave bus up to, say, 16 units, and had a mother-honking transformer with breaker box rated at 1200 amps (!!!), then that max load would be 1200 amps, each wall connector connected via 100A circuits and breakers to that load panel. Or more realistically, a 600 amp service panel with max load of, say, 300 amps available for charging Teslas, and a 4 Tesla household (mom X, dad S, daughter and son each m3), then each wall connector would have a 100 amp breaker and the master would be set for 100 amps max power for itself and 300 amps max power for all 4 wall connectors.

    Come to think of it (I already back-edited this thought into the above paragraph), each slave would need to know its specific breaker amperage -- so there would have to be dual settings on the slaves, as well: one setting for the breaker for that slave (could be anything, not just 100 amp), and another for the setting that it must act as a slave. (As I already said, an artificial restriction that max-total-load-above-100A systems all have 100A independent circuits would be suboptimal but acceptable since the panel would supposedly have enough for 100A and you would just have more stringent requirements for conduit and wire. Preferably, each unit could specify its actual amperage as other than 100A still.) Since the master would require two knobs (one for max amps and one for amps on that particular unit), the slaves would also do the same thing, one knob for amps on that unit and one that says the max amps = I'm a slave and let the master figure it out. With only 4 total in a set today, that's up to 380 amps available to split (>=400amps you don't need to have any slaves), and quite a bit more data bandwidth that can fit in that "unused dip switch" I saw in the manual, but I suppose one could get really crafty and find a subset of good setups for that, such as "if dip is on, knob has settings for I'm a slave on a circuit of 20A, 30A, 40A, 50A, 60A, 70A, 80A, 90A, 100A, or I'm a master and total amps is 125A, 150A, 175A, 200A, 225A, 250A, 275A, 300A, 350A." That's two more slots than are in the bandwidth, so an electrician should pull out the least common, perhaps adjust for the most common use cases -- idk, like nix the 20A slave setting and the 275A total setting. At least that last bit gives that extra flexibility; if this is software controlled, I see absolutely no reason the current units couldn't be firmware upgraded for exactly this ability, and it would make these wall connectors wildly more flexible (although perhaps slightly more complicated to configure, but electricians are good with that, and I conjecture MUCH easier to provision for the use case of homes with above 100A available power where available power is less than 100A * number of wall connectors, I suspect an extremely large percentage of use cases).

    ==========

    Before anybody complains that having 2 or more Teslas is not a problem anybody ought to have consternation about (5 fully loaded Model X's would be almost the price of a house here in California), I should remind you that most electrical installations are fairly expensive, last many decades, and will have to consider a use time when Teslas are old and cheap and commonplace well within the lifetimes of the home electrical setup -- when you could go pick up a used Tesla for way less than $10K and have AT LEAST 4 in the parking lot, and you WILL have a HPWC for every one of them, probably installed more than 8 years earlier.

    By then, everyone will use Uber? We just don't know! (I've never been able to order Uber on my phone, since the app crashes or gives errors every time, and I've heard nothing but horror stories about Uber, such as slow drivers, drivers that want to talk, or drivers that get lost or want to listen to music, or have a crappy car, but driverless would fix all that.)
     
  18. brkaus

    brkaus Well-Known Member

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    If they go above route with lots more smarts, they should likely create a "master controller" with no power functionality at all... add wifi/ethernet/etc. It could drive all the HWPC wired together on the control bus.

    I'm thinking most don't have the kind of power capacity that the above 100A considerations (which are all valid thoughts). Given I have a reasonably new 4000+ sq ft house and the cheap builders only put in 200a main panel... I can only imagine with the general population has that would consider a Model 3.
     
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  19. Cyclone

    Cyclone Cyclonic Member ((.oO))

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    In a residential setting, I think you are overthinking it. If you can support 2x100 amp circuits (or more) in your panel and are ok with the installation costs ($ and affect on walls and joists for any drilling), 2x (or more) non-slaved HPWCs would be the way to go and each supports 80amp max charging independent of the other.

    If you do not want the cost of the wiring, drilling and feeding two conduits, or cannot support 2x100 amp circuits in your home's panel (and don't want to upgrade the panel), then go slave. In the discussions about which car first, if one needs to go out sooner, etc., in a residential setting, the answer is simple -- unplug the car that doesn't have an "urgent" energy need and would "steal" some of the available capacity to the other car.
     
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  20. AWDtsla

    AWDtsla Active Member

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    The new HPWC installation manual calls for #2, doesn't that automatically make #3 violate code because it's less than MFG instructions?

    edit - I see it's:
    For 80A operation, use 2AWG 194°F
    (90°C) rated copper wire or follow local
    regulations.

    Ok I guess the "or" makes it fine?
     

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