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200A service in my house. Looking for opinions.

Discussion in 'Model 3: Battery & Charging' started by ratsbew, Apr 19, 2018.

  1. ratsbew

    ratsbew Active Member

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    Hi. I'm in the planning stages of installing two NEMA 14-50s in my garage and want to get some thoughts on what I can have installed based on my home's 200A service.

    I want two 14-50s installed. I already have an electric dryer and an electric oven.

    Am I correct, that if I add the numbers printed on the breakers in the box it has to be less than 200?

    Based on your experiences, will I go over my 200A limit by adding two 14-50s?

    If so, should I downsize to a 14-30 for the second connection? That will be for a future electric water heater (gas currently).

    I'm planning on using 2 x UMC at 32A so I'm not worried about actually going over 200A total, I just want to be sure that my plan will work when I present it to an electrician.
     
  2. ozymandius100

    ozymandius100 Member

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    Great question. I have 200 amp service as well and am looking to add one NEMA 14-50. The breakers add up to 415. Trying to determine if I need a new sub panel or something or can just have the electrician add the circuit breaker and run the lines.
     
  3. ratsbew

    ratsbew Active Member

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    I'm over 200A in my panel too, but under real use I'll never go over 200A even if I'm drying clothes, charging the car, cooking dinner, and the water heater turns on. I'm just worried about the electrician not allowing it.
     
    • Like x 1
  4. GWord

    GWord Member

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    Your electrician will do a load study to determine if your service is undersized. It is common for your total breaker values to exceed your service rating, just as you might have a single 20A breaker serving a dozen 20A outlets.
     
    • Informative x 1
  5. PacManMX

    PacManMX Member

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    Go on Amazon and buy an electrical usage monitor. The ones that poll every second or in “real-time” are the best. In theory, 200 amp service will give up to 48 kW of power at any given time (200*240 or 200*120+200*120). I have a 14-50 for my MX (8.4kw max), an electric drier, a hot tub with a 4kw heater and which uses up to 14kw when all jets are on, 2 zones of AC, etc.... and have never come close to being at capacity. In three years my max usage at a single point in time was 24kw. Average daily is 70kwh, and maximum was 150kwh. The only thing I look out for is to make sure the drier, hot tub jets, AND Tesla aren’t all running/charging at the same time. My Tesla is set to charge every night at 3am so it’s not something I really ever think about. The calculations that electricians do are based on conservative averages. Having the actual data for your house is much more useful and telling. That said, there may be other reasons to get additional service (my general disclaimer since I’m not an electrician).
     
  6. brkaus

    brkaus Well-Known Member

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    This is the correct answer. Also, as @PacManMX said, it could be conservative. If you do have actual numbers it would help in the discussion. But as things change over time, conservative is typically correct.

    Do you also have electric heat? Air conditioning? How big is your house?

    Your likely to be good with 50A outlet. Not sure about two.


    You could always use two HPWC with load sharing. Then you can set a max amps out of the pair (perhaps 60A). It will cost more, but it is an option to not have to juggle charging two cars and keeping under a specific limit. It will also allow charging higher than 32A on an individual car.
     
  7. yuhong

    yuhong Member

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    Yea, I would consider upgrading to 400A service in that case.
     
    • Disagree x 2
  8. cmaster

    cmaster Member

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    If you use two HPWC instead of two 14-50, they can load share based on the amount of load. Doing this only require one circuit breaker.
     
  9. brkaus

    brkaus Well-Known Member

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    For reference, I was quoted over $15k for upgrading to 400a service. Not including new concrete in the driveway they had to dig up to replace the conduit to the transformer.

    I have 4000+ sq ft, 3 HVAC units, 2 ovens, an electric dryer. I do have gas heat and gas hot water so that helps. They gave me 50A no questions asked. I typically charge at 30a and charged overnight easily. Will be adding a Model 3 and it should easily charge also - probably on an alternating night basis. I personally don't see the ROI on a 400A panel upgrade.
     
    • Like x 1
  10. BerTX

    BerTX Supporting Member

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    Two TWCs are far cheaper than upgrading the service for the house!
     
    • Informative x 1
  11. IdaX

    IdaX Member

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    What BerTX said. Don't get 14-50's: get two Tesla HPWCs. I have two HPWC's myself, one for the X, one for the 3. The load-sharing that they do is brilliant, and they let you keep your UMC in your car for charging elsewhere.
     
    • Like x 1

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