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Service requirement for home chargers

Discussion in 'Model S: Battery & Charging' started by screebo, Dec 20, 2012.

  1. screebo

    screebo Member

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    I recently had a NEMA 14-50 outlet installed at my in-laws for top-offs during visits. I do have twin on-board chargers. I had them put it on a 50 amp breaker and the vehicles charges at 40 amps nicely. If I had installed a home charger would I expect a higher charging rate? My thinking is "no". What size breaker is usually used for a home charger?
     
  2. RandyS

    RandyS Fan of Elon

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    The Tesla wall mount charging station will deliver up to 80 amps, which would require a 100 amp breaker. Of course, other brands of charging stations are available at 20 amps, 30 amps, 40 amps, etc. To accomodate the full-power Tesla wall charger, your electrical service must be capable of adding that much load. That is usually ascertained by conducting load calcs when applying for a permit, not just eyeballing it and saying that that you have breaker space...Do you have a 400 amp panel there now?
     
  3. FlasherZ

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

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    Depends on the EVSE you want to use. There are options for almost any current you want, up to Tesla's HPWC @ 80A.

    The breaker size will need to be 125% of the charging current you plan to use. As mentioned, you must do load calculations to determine whether your service can handle the desired load properly.

    (Note that a 320A service isn't necessarily required for an HPWC unless you have an extremely large home or you have all-electric appliances, including heat.)
     
  4. screebo

    screebo Member

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    Hey Randy,
    Didn't even look. The installer took a quick look and said I was fine for the NEMA receptical on a 50 AMP breaker. The home is at least 50 years old and may or may not have had upgraded electrical service. I had a hunch I'd need a 100 amp breaker for the Home charger to do it's stuff. I didn't feel like springing $1400 for faster "in-law" house top off's at this point but my curiosity was killing me. Next time I'm up there I'll see if I can determine the service panel's rating. Thanks for your reply and happy motoring!
     
  5. TXjak

    TXjak Owner/Investor/Advocate

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    Conceivably there could be a 70 amp J1772 home charging station available, but they would still need at least 85 amp circuitry.
     
  6. swegman

    swegman Member

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    When my house was built 17 years ago, the electric utility installed 800A service to the house. This feeds four 200A panel boxes. The transformer serves my house and the house next door. I should be ok for installing multiple HWPC's, if I want to.
     
  7. mknox

    mknox Well-Known Member

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    Best to have a licensed electrician make that determination for you as there are so many variables. My older house has a 100 amp main service with gas heat, but electric range, clothes dryer and water heater. I need a new dryer anyway and will replace it with gas, and I already have a new gas range just waiting to be installed to replace the old electric one in the new year. With that done, I should be good to go with a 50 amp NEMA 14-50 in the garage.
     
  8. jkirkebo

    jkirkebo Model S P85+ VIN 14420 EU

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    Wow, 800A ? That is a whopping 192kW(!). My house has 25kW available and that is way above average in Norway. And we use electricity for everything. No gas, oil or firewood used at all.
     
  9. FlasherZ

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

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    Can I get a picture of your service entrance equipment, meter base, etc.? 600A and 800A typically require special service cabinets for the entrance, and I'm just curious how it was built. I'd have to go to 600A if I wanted a second high-amperage charger.
     
  10. swegman

    swegman Member

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    There is not much to see. There electric wires run through a hole through the foundation wall into a gigantic metal box. A trough (is that correct?) runs from the box, and 4 200A panels are located perpendicular to the trough. The power meter is located on the side of the house (outside) about 100 feet away, and is inductively coupled to the electrical supply wires. BTW, the metal box has a clip with a seal on it from the electric company, that prevents the opening of the box without them being able to detect that it was opened.

    If you still want a picture, tell me how to post it here and I'll do it. Or PM me your email address and I'll email it to you.
     
  11. mknox

    mknox Well-Known Member

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    Not to mention utility metering. A service this large would require transformer-rated metering.
     
  12. stevezzzz

    stevezzzz R;SigS;P85D;SigX

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    Do you really need 80 amp charging even at home? Most people will do just fine with a 14-50 and a 40 amp charge rate. Unless you drive way more than average and need a mid-day charge to make afternoon/evening rounds, why spend the extra $$$? I've driven a Roadster and and now a Model S more than 20,000 miles and never, ever been left wishing I'd installed an 80amp charger at home.
     
  13. KenEE

    KenEE P1937 Reward Excellence!

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    At home maybe not so much, but at your destination you may need as fast as you can get. I'm in a situation where the three inlaws we visit are far enough away that we will arrive with little range left. So if we want to go somewhere once we arrive we'll need a fast charge.
     
  14. yobigd20

    yobigd20 Well-Known Member

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    Holy crap. How much is your electric bill every month? lol time to go solar man....
     
  15. Babylonfive

    Babylonfive Power12

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    Service ratings are MAXIMUM capability, not a forced power loss or usage. He doesn't have any worse a bill than anyone else, unless he chooses to consume up to the max rating (400A for him, as he said the 800A service is split into 200A boxes, and that he shares with the neighbor house).
     
  16. CanuckS#69

    CanuckS#69 Member

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    Exactly so. My home has 600A service due to being built in the 70's when hydro was dirt cheap and electric resistance baseboard heaters were common. I've been on a geothermal system for 25 years and have tons of unused capacity. Unfortunately, only 100A is wired to the garage and that includes the geothermal system and well pump, so I'm stuck with a 14-50 for now. I have my own pole transformer, so there's plenty of available juice, but running new service lines can be costly.
     
  17. swegman

    swegman Member

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    No, no. I have 800A service to my house. I said the transformer, which is located outside, is shared with my neighbor. Sorry if that was not understood. I have 800A service with four 200A panel boxes.

    The house is about 10,000 square feet and has 4 geothermal HVAC systems. The first panel box is connected to the lights and is maxed out. The second panel box is for outlets. The third panel box powers the heavy equipment, like the HVAC systems, refrigerator, etc. The fourth panel box is dedicated to the theater. Electric bill varies each month, from a low of about $280 to a maximum of just under $1,000 (usually Feb., when it is really cold). Averages out to about $500/month. The geothermal HVAC system saves a tremendous amount of money.
     
  18. FlasherZ

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

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    What an odd way to divide the service panels, but I think we're getting way off-topic here. :) 200A for lighting -- well, at least you can have one hell of a Christmas display!

    I have 320A service on 2 panels, but I have the added challenge that they're divided between standby circuits (backed up by generator) and non-standby circuits. Going to 600A requires a whole new set of challenges because the cable, meter, and entrance equipment change significantly.
     

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