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HPWC Amp and Wire Specifications

Discussion in 'Model S: Battery & Charging' started by chriSharek, Apr 3, 2015.

  1. chriSharek

    chriSharek Member

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    I'm preparing for my baby 9 months out (fitting, right?). I hope to take delivery prior to our annual Thanksgiving trip to Grandma & Grandpa's. I'm getting a single charger S85. Is the spec for the HPWC a 2-pole 40 amp breaker or 50? Also, based on the breaker size, what size wires will I need? #6? Thanks for the help.


    And just FYI, I did try to search and find answers on this on Tesla's site as well as this forum with little success.
     
  2. wycolo

    wycolo Active Member

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    Its all in here ad infinitum- just keep searching. doug never throws anything out!
    --
     
  3. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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  4. dirkhh

    dirkhh Middle-aged Member

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    By default the HPWC requires a 2 pole 100A breaker and #3 wire

    Or to quote FlasherZ's home charging FAQ

    WHAT WIRE SIZES SHOULD BE USED FOR INSTALLING MY HPWC?

    Note: All wire sizes assume copper conductors!

    For wire-in-conduit, 3 AWG THHN (dry locations) or THWN (wet locations) is sufficient to carry 100 amps, but many electricians will use 2 AWG to ensure there is enough headroom, and it’s carried more widely by supply houses. The ground wire must be a minimum of size 6 AWG.

    I am told that Canadian consumers have the option of type NM cable (3/3+ground) for this installation, but NEC does not permit this (because 3 AWG must be used at the 60 degC rating, only 85 amps).

    If these conductors will ride in the same conduit as another circuit, they must be “de-rated” and 2 AWG is required.

    If the HPWC is set to 40A charging with the little dip switches then technically 8AWG on a 50A breaker should be enough.
    The breaker always needs to be 25% higher than the continuous charging current.
     
  5. SabrToothSqrl

    SabrToothSqrl Active Member

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    you can adjust the dip switches for your install, but with only one onboard charger, there is no advantage to the HPWC... wire in a NEMA 14-50 with 6 gauge wire and a 50 amp breaker.

    the HPWC, to run the full 80 amps needs 3 gauge wire and a 100 amp breaker.

    I'm still on the fence about the HPWC, that way I can leave my UMC in the car for simplicity. (I've never driven w/the UMC in the trunk).
     
  6. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    This is true in the vast majority of installations, but is not true "always"; the code does allow for breakers that are rated for 100% continuous load. For example, the breakers used in Tesla's Superchargers are rated at 100% continuous load and are sized that way.

    That being said, I don't know of any breakers available for home sized panels that are 100% continuous rated. For all installs that we are likely to see in our houses, the breaker must be sized at 125% of the continuous load, or stated another way, the continuous load must be no more than 80% of the breaker size.
     
  7. jthompson

    jthompson JThompson

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    Tesla has an HPWC install handbook they can give you (or I can send you). But I am curious - if you have a single charger, you will not be able to use the 80 amp charging capability the HPWC can provide (you are limited to 40 amps with a single charger). Why not go with a less expensive NEMA 14-50 outlet and buy an extra UMC? Or are you planning on buying the second on-board charger after delivery?
     
  8. SW2Fiddler

    SW2Fiddler Bannd Member

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    #8 SW2Fiddler, Apr 3, 2015
    Last edited: Apr 3, 2015
    ANY way we could convince you on a second charger?
    I might be waiting to charge after you some day at a public charger greater than 40A.
     
  9. chriSharek

    chriSharek Member

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    #9 chriSharek, Apr 3, 2015
    Last edited: Apr 3, 2015
    @FlasherZ: Thanks! I am horrible at searching these sites. Most appreciated.

    @JThompson: The additional UMC is $650, right? At $750, I can get the permanently installed HPWC wired in with a holster and all. Plus, I understood that the NEMA plugs are not meant for outside (I have a carport; the wife gets the garage for her open top jeep)

    Will the UMC automatically pop the charge door open like the HPWC will?

    - - - Updated - - -

    SW2Fiddler, what public charging station do you know of that's > 40A? You know the Superchargers bypass the onboard chargers anyway. I'd rather have the SAS than the dual chargers! :)
     
  10. jthompson

    jthompson JThompson

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    @chriSharek: Sorry about that! I have not kept up with Tesla accessory pricing and did not notice the HPWC prices fell so far from what it was originally. And you are correct about the exterior install - the HPWC is fine for that. Although numerous members (severla of them good friends of mine) have also setup to use a spare UMC outside, and it works fine as well. And yes, the button on the UMC and HPWC do both pop open the charger port.
     
  11. FlasherZ

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

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    Yes, the silver button on top does the same.

    Even if I could only configure it for 40A charging load (50A circuit size), I would still consider a wall connector. They're now much more reasonable ($750) and they allow you to keep your mobile cord in the car without having to wrap it up for trips; they are built for heavier duty, and the cord is 7' longer. You can put it on a variety of circuit sizes, depending upon various factors (whether your service can support it, etc.).

    - - - Updated - - -

    I know where you can get them, but as you say they're special-purpose and on a per-amp basis they're far, far more than the overall cost of sizing to 125%. So I don't even talk about them, so as not to confuse anyone here. :)

    - - - Updated - - -

    The difference between UMC and HPWC now is $100. I think the marginal benefits of HPWC over second UMC are far greater than the $100 cost. That was not true when the HPWC was $1200, though.
     
  12. chriSharek

    chriSharek Member

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    @FlasherZ, you are bang on. That is exactly why I was going to get the HPWC: holster, outside install, permanent, and allows me to keep my mobile connectors in the car, MOBILE! I currently have a "HPWC" for my Volt that I'm planning to move for my son. It's worked great for 4 years and that allows me to keep the 120V charger in the trunk for mobile opportunities.

    @Lloyd - thanks. This install guide is more comprehensive and detailed than the older one. The one page showing the dip switches (had to stop giggling like a girl) clearly shows that a 40 amp or 50 amp breaker could be used. And for a single charger on the car, I'll opt for the 50 amp to get my maximum 29 miles/hour of charge. But, looking at your ampacity chart, if I'm pulling 40 amps, I only need to use a #8 wire? That doesn't sound sufficient for some reason.
     
  13. Lloyd

    Lloyd Active Member

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    Remember to add 20% for continuous use. For a 50 amp breaker I would use #6.
     
  14. FlasherZ

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

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    See my FAQ in my signature.

    If you're using wire-in-conduit, #8 is sufficient for 40A charging load (50A circuit rating), assuming typical THHN.
    If you're using NM-B (Romex), you must use #6. Article 334 specifies that Romex cable ampacity must always be considered from the 60 degC column, except inspecific derating situations, but must never be more than the 60 degC column.

    - - - Updated - - -

    You add 25%, not 20%. Charging current * 1.25 = wire/breaker size requirement. So 40A charging load requires conductors & breaker at 50A.
     
  15. SW2Fiddler

    SW2Fiddler Bannd Member

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    #16 SW2Fiddler, Apr 3, 2015
    Last edited: Apr 3, 2015
    Charging Time. Arguably, the single possible compromise/limitation/downside of an amazing car ownership experience. Why anyone would not want to minimize this as much as possible, why even Tesla Product Specialists have been heard to advise against a second charger, maximizing - future-proofing - the car's charging capability, I just cannot fathom. At least the dual-charger option is no longer a Get-It-At-Factory-Or-Regret-It decision; you have lots of time before and after baby's delivery :)

    I'll answer your question with where my Duals should help out (me, and Anyone Waiting For Me To Finish) on a hypothetical trip towards your area. Does not even list non-Tesla >30A spots like Sun Country Highway, which are still increasing. Many Tesla owners find they do want to travel MUCH more than they did in their previous cars.
    I would be shocked if this list ain't about doubled by your Model S's first birthday, too:
    FLORIDA

    Boca Beach Club, Boca Raton
    Charger

    Boca Raton-Town Center at Boca Raton
    Store

    Waldorf Astoria Boca Raton Resort & Club
    Charger

    Bonita Beach Vacation Rental Home, Bonita Springs
    Charger

    South Seas Island Resort, Captiva
    Charger

    Dimmitt Automotive Group Collision Center, Clearwater
    Charger

    Dania Beach
    Store, Service Center

    Bahama Bay Resort, Davenport
    Charger

    Banyan Air Service, Fort Lauderdale
    Charger

    Hilton Fort Lauderdale Beach Resort
    Charger

    Victoria Park Hotel, Ft. Lauderdale
    Charger

    Cheeca Lodge & Spa, Islamorada
    Charger

    Jacksonville
    Service Center
    COMING SOON

    Four Points by Sheraton Jacksonville Beachfront
    Charger

    Ocean Key Resort and Spa, Key West
    Charger

    Orlando-Longwood
    Store, Service Center

    Port d'Hiver Bed & Breakfast - Select Registry, Melbourne Beach
    Charger

    InterContinental Miami
    Charger

    Mandarin Oriental, Miami
    Charger

    Miami-Dadeland
    Store

    Eden Roc Miami Beach
    Charger

    Miami-Lincoln Road, Miami Beach
    Store

    The Ritz-Carlton, South Beach, Miami Beach
    Charger

    GEM Remotes, Naples
    Charger

    Ritz Carlton - Golf Resort, Naples
    Charger

    The Ritz-Carlton, Naples Beach Resort
    Charger

    The Breakers, Palm Beach
    Charger

    West Palm Beach Riviera Beach
    Store, Service Center

    Sarasota-University Town Center
    Store

    Four Points by Sheraton Tallahassee Downtown
    Charger

    Eddie V's Prime Seafood, Tampa
    Charger

    Epicurean Hotel, Tampa
    Charger

    Tampa
    Store, Service Center

    One quote and I am off the soapbox...
    Frequently stated at the Houston Galleria HPWC and HPC: "But I only got Single Charger, or I'd be done sooner. Sorry!"
     
  16. chriSharek

    chriSharek Member

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    Just a follow up on the install. I went to Home Depot to get the #6 wire and the #4 was a penny more per foot! Since I was going 90 feet, I thought it would be better to get the #4. It was a challenge cramming two of them through my 1" conduit with the #8 ground, but I managed!
     
  17. FlasherZ

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

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    Great to hear... 2 #4's and a #8 should have gone fairly easily through a 1" conduit, even at 90 ft - what was the biggest challenge?
     
  18. mitch672

    mitch672 Active Member

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    now that you have 95A rated THHN, you might consider buying a 70A breaker, if your panel can support the load, in case you have a visitor with a dual charger...
     
  19. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    The new HPWC's can be set to 100, 80, 50, 40, 30, 20, or 15 Amp breakers for 80, 64, 40, 32, 24, 16, or 12 Amp charging. See page 16 of http://www.teslamotors.com/sites/default/files/pdfs/tesla-wall-connector-installation-80A-12A.pdf

    With #4 wire, you may want to consider putting in an 80 Amp breaker and setting the HPWC to 80/64 for 64 Amp charging.
     

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