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Is a HPWC/80A charging possible with this panel?

Discussion in 'Model S: Battery & Charging' started by mnx, Jul 25, 2013.

  1. mnx

    mnx 2013 P85

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    It has a 200A main breaker (which is just outside the picture)...

    The breaker labeled washrooms is 125A. I am assuming it is likely due to baseboard heaters etc. Unfortunately I just noticed that you can't read the breaker to the right of it...

    tmp_panel.jpg

    Any thoughts?
     
  2. Langzaiguy

    Langzaiguy Member

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    I would say doubtful. Do you have electric heat (pump), water, and/or dryer?
     
  3. mnx

    mnx 2013 P85

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    This is at a local track, thought I'd get opinions on here before I got an electrician out to look at it. I didn't think of having an electric water heater in the bathrooms, that might make sense...
     
  4. Lloyd

    Lloyd Active Member

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    I say likely without any issues!
     
  5. Langzaiguy

    Langzaiguy Member

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    I would think that you would need a 100amp breaker to charge at 80amps continuously in which case you could not install it and pass inspection.
     
  6. Lloyd

    Lloyd Active Member

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    Why?
     
  7. NigelM

    NigelM Recovering Member

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    You need a 100A breaker for the Tesla HPWC. Other than that I don't think that anyone can give you an answer by looking at the photo; the question isn't whether you've got space the question is what else have you got drawing load. E.g. you might have a 125A breaker for the washrooms but the actual draw could be a lot less....IIRC don't washers run on 20A circuits even though they only draw ~12A?

    Having said that, I'll step back and wait for FlasherZ to comment. If you don't see a post from him, then drop him a PM and ask.
     
  8. mitch672

    mitch672 Active Member

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    It's likely the 125A breaker for the bathrooms is for those "instant on" hot air hand dryers, found in bathrooms these days... They draw a lot of power, occasionally when run.
     
  9. NigelM

    NigelM Recovering Member

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    #9 NigelM, Jul 25, 2013
    Last edited: Jul 25, 2013
  10. Langzaiguy

    Langzaiguy Member

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    Circuits are rated for peak capacity and aren't many to run at peak continuously. I'm no electrician, but it seems as though you must plan for the worst--that is, the heaviest usage. I doubt any electrician would install breakers rated higher than what the panel can provide... even if you plan not to charge while drying/heating.
     
  11. RandyS

    RandyS Fan of Elon

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    To get a permit here in San Diego (and many other jurisdictions), very specific load calculations must be done (usually by the electrician or contractor). You may have plenty of open breaker positions but that doesn't really matter as much as how much power is coming in to the panel (conduit, size of breaker) and how much connected load you already have...There are prescribed rules about what to take into account with the calculations, so the getting the calcs done would be the first step...

    If the panel won't support a 100 amp breaker to charge at 19.2 kW (240v at 80 amps), you can always adjust the dip switches inside the HPWC to reduce the output...

    In actuality, not many drivers really need to recharge at a full 80 amps....Do you have the second on-board charger to take advantage of charging current above 40 amps?
     
  12. mitch672

    mitch672 Active Member

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    #12 mitch672, Jul 25, 2013
    Last edited: Jul 25, 2013
    Sure, but we don't know how many bathrooms they have (minimum is probably 2, men's/women's), and how many dryers per bathroom there are. In other words, all of the "Internet Electricians" are not going to be able to perform a load calculation without a lot more information :)
     
  13. rolosrevenge

    rolosrevenge Dr. EVS

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    In theory you should be fine with a 125 A breaker, but that depends on what else is running on the circuit. If you've got a 200 A panel you're cutting it close with everything else in the house. I'd need more load details. The electrician who'll install it will be able to tell for certain.
     
  14. Lloyd

    Lloyd Active Member

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    #14 Lloyd, Jul 25, 2013
    Last edited: Jul 25, 2013
    Typically panels breakers total draw will be much more than the capacity of the panel simply because they are not used all at the same time. There is a load calcculation to do. You need to find out what the other breaker is for, and I would bet that the GFI's for the bleachers are occasional use only.

    Example: Here is a panel at my office breakers total 850 amps on a 200 amp panel.

    panel.jpg
     
  15. mnx

    mnx 2013 P85

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    Thanks guys, I guess I won't know for sure until I have an electrician have a look. I'll let you know what they say...
     
  16. FlasherZ

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

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    The good news is that several have said everything I would say. :)

    Sometimes feeders are simply sized for future growth, so there is no way based on just that picture to make any assumptions about the 125A feeder to the washrooms. My guess is that it would be under that (although those older World hand dryers are rather bursty on start-up).

    My opinion for you - you'll be fine. You may have to turn the HPWC down to 64A or 72A (80A or 90A circuit, respectively) if your electrician finds your load calcs work out a bit hot (depends really on what the washroom panel looks like).
     
  17. ahaer

    ahaer Member

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    You need to look at the size of the breaker in the main panel that feeds to the sub panel you pictured. The size of this breaker will indicate the load the how much current the wires between the panels was meant to handle - ie they pick the main breaker so that it will trip before the panel can draw enough power to melt the wire. Once you know that you can determine if there is enough "spare" power available. I don't know what the formula is but the total power rating of the breakers in a panel is many times the power coming in...

    My guess it that given the number of positions unused in the panel there is plenty of spare capacity...
     

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