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HPWC Professional Installation - anyone get it?

Discussion in 'Model S: Battery & Charging' started by RonnieKorbas, Apr 18, 2015.

  1. RonnieKorbas

    RonnieKorbas Member

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    Has anyone installed the HPWC professionally?
    I'm buying one, and I'm pretty sure I can install it myself, saving hundreds of dollars.
    I installed, successfully, the Nema 14-50 box in my garage, with no issues at all.

    But the HPWC doesn't seem as simple as the 14-50.

    I just don't want to pay $1500 for an installation that won't cost me more than $100.

    Anyone get it, and how much did they charge you???

    -Ronnie
     
  2. efusco

    efusco Moderator - Model S & X forums

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    I think it really depends upon your knowledge, the set up of where your fuse box is and what voltage you have available, and how far you need to run wires and such.
    I don't think, for most people, it should cost more than a couple hundred dollars to have it professionally installed. My install was a bit over $2000, but required a separate subpanel and over 80 feet of new wire to be run, plus the charge for the HPWC hookup.
     
  3. invisik

    invisik Member

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    We had only 100amp service to our house, so we needed a new breaker panel for 200amp service. We had them do that and the HPWC (had to cut through some drywall, etc, to run the cabling for it) all at once.

    Get a couple of estimates and/or ask your local Service Center (or Tesla group) for recommendations...

    -m
     
  4. sorka

    sorka Active Member

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    Have you done the NEC 220 load calcs to determine if your existing service panel and service conductor sizing can handle the new load? If not, then the answer is no, this is not something you can do yourself. If yes, the answer is maybe but it depends on a hundred other factor.

    Working with a 2 gauge pull in a 2/3 NMB, assuming you're pulling through wood is a pain in the you know what. If you're doing conduit installation only from the service panel, you can get away with 3 gauge wire.

    There are literally hundreds of things you need to know about NEC code and probably dozens of additional local code.
     
  5. RonnieKorbas

    RonnieKorbas Member

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    Well, it's pretty safe to say, since I'm asking about it here, that I won't be installing according to code. Which is why I'm asking here.
    I know most of code here, in Texas, and I Was able to install the nema 14-50 about 90% to code.

    However, my house IS pretty old, so, I might need to upgrade my box. I have a 150 box right now.

    Other than that, I trust myself in my savvy and knowledge to do this on my own.

    But if a professional installation is not that much ($500, give or take a couple of hundred), then it might be worth it to go ahead and do that, than take the chance myself.

    -R.
     
  6. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Get a few bids; that isn't too hard and avoids too much speculation.
     
  7. pan

    pan Member

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    I had a HPWC professionally installed just outside of Boulder, CO. In addition I had a Nima 14-50 plug installed at the same time. Both the HPWC and the 14-50 plug where installed within 3' of the panel in my garage. Although the direct line is 3' for the HPWC it still took about 8' of cable to manage the exit from the box to the HPWC through a flexible conduit. The cost was just above $500.

    The installation between the 14-50 and the HPWC is not to different but there are differences. The first is you need a #3 wire assuming you are going for the max current. That is not any fun to work with that heavy of a wire in the confined space of HPWC. The connection from the conduit requires an extra long nipple but not to long to make it through the thickness of the HPWC side. That alone would most likely have been one or two trips to the hardware store. To me my time was more valuable and my lack of experience made it more costly to fight the installation than it was to hire it out.
     
  8. sorka

    sorka Active Member

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    You can only use 3 gauge wire if you're running it in a conduit and only for short distances. For pulls from attics and walls, there is no NM-B in pvc flex housing that has 3 gauge so you have to go one larger.

    It's a pretty good bet that a 150 amp panel cannot handle adding an additional 80 amps.

    Is 40 amps not fast enough? I know in my situation there will be times we need to charge as quickly as possible which is why I went dual charger and HWPC, but most people won't fall into my 260 mile round trip commute scenario.
     
  9. FlasherZ

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

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    2/3 NM-B will not work for a 80A charging (100A breaker) HPWC, because 2/3 NM-B must be used at the 60 degC column, and that's 95A rating. You'd have to use the 80 degree column.

    2/3 NM-B is overkill anyway, because you only need 2 conductors and at $6/foot, 2/3 is rather expensive and they don't have 2/2 easily available.

    For anything larger than #6, conduit is much easier because you start to run into some pretty serious bend radius rule problems with #4 and #2 cables. And we can't use the 3/3 NMD-90 that Canada does.

    - - - Updated - - -

    The Tesla charging will be the largest load in terms of kWh consumed that your service will ever see. Do it to code, please... it's just not worth it to cut corners.

    - - - Updated - - -

    See above... you can't even use 2/3 NM-B for 80A charging (100A breaker).

    #3 is just fine for long distances in conduit, provided it's copper. At that gauge, you don't have to worry about voltage drop all that much, and there's no difference for ampacity for circuit length unless voltage drop is an issue.
     
  10. davewill

    davewill Member

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    That's no reason. All you have to do is pull a permit and have it inspected. I wouldn't skip it for something like this.
     
  11. sorka

    sorka Active Member

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    If you're doing a pull through wood members and inside walls, you really don't have a choice unless you want to rip out your drywall and install conduit. So using NM-B is you're only choice.

    You may use us a conductor rated for 95 amps with a 100 amp breaker in this application. In cases where the conductor rating is between breaker sizes, you may round up to the next size breaker as long as certain conditions are met. See NEC 240.4(B) or just ask any licensed electrician. I did.

    Both estimates I have from contractors I didn't use both specified in their big using 2/3 NM-B with a 100 amp breaker.
     
  12. FlasherZ

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

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    #12 FlasherZ, Apr 19, 2015
    Last edited: Apr 19, 2015
    No, you may not. Article 240 applies to the OCPD (breaker) only. NEC 240.4(B) states "the next higher standard overcurrent device" (a/k/a breaker). However, 210.19(A)(1)(a) says, very specifically, that "the minimum branch-circuit conductor size shall have an allowable ampacity not less than the noncontinuous load plus 125 percent of the continuous load". There is no "next size up" exception for the conductors - only the breaker. For an 80A charging load, you require a conductor rated at 100A. A 95A rated conductor (NM-B 2/3) is an illegal installation. See this article for more information: Mike Holt Conductor Sizing and Protection

    Let's say you have an appliance - non-continuous - that has a minimum circuit size requirement of 95A. In this case you could use 2/3 NM-B to feed it, because the wire meets the 95A the appliance demands, but you would indeed protect it with a 100A breaker. In the case of the HPWC, you are required to have conductors rated at 100A (125% of 80A) because that's what the nameplate says.

    This scenario is tested in every single code/license test that I've ever seen, because it's a fundamental building block for electricians. If your licensed electrician told you that 2/3 NM-B could be used for an application requiring 100A, you need to find a new electrician.

    With #2 NM-B, you also run into some pretty serious bend radius issues. Southwire's 2/3 NM-B is 952 mils in diameter, so you need 4.76" bend radius just to accommodate it. It won't fit inside a 2x4 wall at all legally (because you can't legally make the bend for it to come out of the wall), and it won't fit inside a 2x6 wall without it being too dangerously close to the other side of the wall. Bend radius on NM-B cables are based upon the entire cable's diameter, while the bend radius on THHN-in-conduit is based on the individual conductor.

    If you have one, let alone two, contractors who have provided estimates using #2 cable via NM-B, then either it's because you suggested/asked them to, or it's time to find a new contractor. It's a pain in the ass to deal with, my supply house doesn't even carry it without special order, and working it in closed walls is nearly impossible if you're paying attention to bend radius.

    PS: When working in pre-existing walls with circuits this large, it's much easier to use liquidtight flexible non-metallic conduit. You can fish it without a problem, you can manage transitions out of the wall easily (because the conduit can be exposed on the surface - it means physical damage protection requirements), then once it's in place the wires flow pretty easily. I use rigid PVC in accessible, then transition using appropriate fittings to LFNC to deal with closed walls and other inaccessible areas (or just use LFNC everywhere, depending on run length). 356.30 allows for LFNC to be unsecured where fished, as long as it's supported properly at the top or bottom of the wall where you're installing.
     
  13. sorka

    sorka Active Member

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    Actually, it was 4 electricians in all. But two of them put it in writing.

    Plus, I'd better make sure that the county inspector who approved this and looked at each and every material used for the job needs to be get fired too. As far as running 2/3 through 2x6 walls, there are about a dozen different ways to get around the issues you bring up all still within code.

    You're doing a lot of reading and jumping to incorrect conclusions.

    This is why the OP, if you're going to attempt this, should hire an electrician to tell you what to and what not to do and don't do it without getting it permitted and inspected. If you do and your house burns down, your home owners insurance won't cover it if.
     
  14. bonaire

    bonaire Active Member

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    Does saving on an electrician also mean skipping a county or local permit for the installation? I think a call to your homeowners insurance company should be made to ask if they fully insure against loss for higher amperage self installed electrical work.
     
  15. sorka

    sorka Active Member

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    They are not mutually exclusive. However, if you do a self install that is permitted and inspected, no home owners insurance can deny you coverage simply because you did the install yourself.
     
  16. FlasherZ

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

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    #16 FlasherZ, Apr 19, 2015
    Last edited: Apr 19, 2015
    Now it's 4 electricians. I'd love to see it. As I mentioned, this is a situation that is asked every single time in every code test I've taken and seen - there are a lot of amateur handymen who have heard that you can "round up to the next breaker" -- plainly put, it's WRONG. There is no argument, 310.19 says conductors must be of sufficient ampacity, and #2 Romex is good to only 95A.

    And yes, the county inspector is indeed not following NEC if he passed inspection for a 95A conductor. My guess is that the electrician and/or inspector assumed it was an 80A intermittent load (which would be legal on a #2 NM conductor) vs. an 80A continuous load. If so, they weren't aware that 625.40 states that all EVSE charging loads are continuous duty, and circuits must be rated at 125% of the offered charging load.

    I see you posted the question to the DIYforum. I'll respond there too.

    Tell me what conclusion I'm jumping to that is incorrect. You're saying that a 95A rated conductor is sufficient for a load requiring a 100A circuit rating. 310.19(A)(1)(a) tells me that the conductor must be rated at 100A. 334.80 tells me that any cable rated as NM, NMC, NMS must be considered as a 60 degC conductor. 310.15(B)(16) shows us that the 60 degC rating for a #2 conductor is 95A. Ergo, it is a violation of the NEC to use NM-B 2/3 cable for an HPWC installed at the 100A circuit configuration.

    Please cite the code provision that gives you permission to use a conductor rated at 95A for an 80A continuous offered load (and therefore a 100A circuit rating).

    - - - Updated - - -

    No. If permits and inspections are required, you are required to get them.

    In most states, if you're not a licensed electrician, you are permitted to do your own electrical work on your home, provided you follow permit and inspection requirements. However, many states have restrictions if the home is a multi-family dwelling or is commercial property.

    I said it above, I'll say it again - the Tesla is the highest-load (in terms of kWh consumed) appliance that 95%+ of Tesla's customers will ever come across. Unless you understand how to install it properly - and know the details of the code - you should give someone qualified a call.
     
  17. FlasherZ

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

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    I noticed at DIYforum you said you were configuring the HPWC at the 80A breaker setting, in which case you'd be legal with 2/3 on an 80A breaker. You'll be ok and compliant with a 100A breaker here with the HPWC set to 64A charge / 80A breaker.
     
  18. jcaspar

    jcaspar Member

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    I would do it yourself if you have experience with electrical work. I did a similar install in my garage. Ran 2/3 NM about 35 feet to a 100 amp sub panel with two 25' 6/3 branches for 14-50 outlets. Total cost was about 450$ and it looks much better than my friend's done by an electrician as there is no conduit, all in the walls or under house. Had to have it inspected by an electrician before he would install the dedicated EV meter. He liked it so much he offered me a job!
    IMG_3153.JPG
     
  19. sorka

    sorka Active Member

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    I said I had two written estimates that quote using 2/3 NM-B. I didn't say I hadn't consulted with more electricians which I did in fact do. If you include those in the DIY forum, then it's in fact more than 4.

    Also, as I stated over there, the 64 amp setting is only temporary until I upgrade the 4 gauge to 3 gauge wire from the safety switch to the HPWC.

    That said, one factor not in favor of one of the electricians who gave me a written estimate said that a safety switch was not required because it wasn't a motor load but they were wrong and it's required for an 80 amp appliance even if it doesn't have a motor load, so I used one.
     
  20. FlasherZ

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

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    It appears you're not deterred by letter of the code, but just as a reminder to anyone else, 2/3 NM-B (Romex) is illegal for an 80A charging (100A circuit) configuration because it's only rated for 95A. If your inspector passes you, you got a bonus-you'll escape liability.

    Most electricians prefer using conduit and wire for high current installations. Follow your licensed electrician's recommendation and you should be fine.

    Good luck.
     

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