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Condo owner -- NEMA 14-50 with 100amp service (gas heat/stove/dryer/hot water)

Discussion in 'Model S: Battery & Charging' started by tanker5, Nov 16, 2015.

  1. tanker5

    tanker5 Member

    Apr 21, 2015
    I live in a townhouse style condo with an attached garage and am expecting to take delivery sometime next month. My electric service is 100 amps. I have natural gas heat, with a gas stove/oven and gas dryer and gas hot water heater. My air conditioner runs on a 30 amp circuit. Other major appliances are refrigerator and microwave and dishwasher.

    I asked my Tesla-recommended electrician if he recommends me installing a 30 amp outlet or a 50 amp outlet (typically, I drive about 40 miles/day). He told me I should be fine having a NEMA 14-50 outlet on a 50 amp circuit installed since I have gas heat and hot water, etc. the installation was completed a few days ago.

    I can't help but be concerned about the amount of power being drawn in the summer with my air conditioning running and my car charging. Should I be concerned, or am I worrying about this for nothing??
  2. David_Cary

    David_Cary Member

    Dec 17, 2012
    Cary, NC
    Well - if you are concerned, you should know that you can set the car to only charge at 30A (or 27 or 10). Then if you need the 40A one day, you can easily change it back. You most likely will need/want 40A in the winter so that works well.

    Your A/C probably pulls significantly less than 30A once it starts. So there is that.

    I have a 4 ton unit that pulls about 20A when running. I would think a condo in CT would not need even 4 tons.

    But even if you are charging at 40A, a/c at 20A, that still leaves 40A. Without heat making appliances, it is very hard to use that much electricity. I have an energy monitor so I know what I use.

    You can do it but it would be very hard (microwave, toaster oven and dishwasher all running) and what would happen - the breaker would pop. Not the house burning down.

    Set the car to 30A in the summer. Done.
  3. Rockster

    Rockster Active Member

    Oct 22, 2013
    McKinney, TX
    And you can program the car to charge at night when your AC is running less. That's what I do in the summer months here in Texas.
  4. paulkva

    paulkva Member

    Jul 22, 2013
    Falls Church, VA
    In addition to David's excellent points, you will likely do most of your charging overnight, at which point the other appliances (even the AC) won't be working as hard, if they're running at all. So I don't think you'll have to worry, even at 40A. On top of that, if you drive 40 miles/day, you could probably set the car to charge as low as 10A and still regain 40+ miles overnight (not that I'd recommend doing so).
  5. cinergi

    cinergi Active Member

    Sep 17, 2010
    You'll be fine. I had the same setup at my previous home for a couple years -- and I didn't pay attention to what time of the day I charged the car.
  6. AB4EJ

    AB4EJ Member

    Feb 25, 2015
    Tuscaloosa, AL
    Agreed. All your big appliances are gas, you have very little load on your electrical system.
  7. FlasherZ

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

    Jun 21, 2012
    A/C condensor units and blower units usually have a larger breaker for initial start-up load. Once they're running (after a couple of seconds start-up), the load is much lower than the breakers might indicate. The only thing that would really concern me competing in a condo on a 100A service would be electric heat. There are several "load calculation" tools on the 'net that can help you, but just from your description I think you're good.
  8. jkliu47

    jkliu47 Member

    Apr 30, 2013
    Glendale, CA
    OP, I own a single family house, and except for an extra refrigerator in the garage, have the same appliance setup as you. When I planned for the Tesla and installed a 14-50 power source in the garage, I didn't increase the 100 Amp service to the house because of the prohibitive cost of trenching and laying the extra power line from the utility power source.

    Except for a few instances in summer nights when my AC kicked in after midnight (when the Tesla charging is scheduled), I have been able to charge at full 40 Amps with no hiccups. Even then with those instances the current software senses the voltage drop at the charging port and automatically drops the charging current to 30 Amps and continues charging.
  9. Rocky_H

    Rocky_H Active Member

    Feb 19, 2015
    Boise, ID
    Our situation is kind of similar to yours, and it’s not a problem because of the offset day/night things. Ours is a 1600 sq ft house that has a 125A main service. We do have A/C, oven, and dryer that are the big electric loads. But since oven and dryer are something you run on purpose, it’s easy to just not use them in the middle of the night when the car is using the 14-50. And I have the car set to use only 31A anyway, so it’s a little less.
  10. David29

    David29 Active Member

    Aug 1, 2015
    My condo is somewhat similar -- 100 amp service but my unit also has a 30-amp circuit for an electric dryer (so that people can install either electric or gas) and has a 50-amp circuit for the AC. Since we have a gas dryer, we do not challenge the 100-amp breaker but I assume that the service is adequate for use of an electric dryer when the AC is on. So my guess is that you would also be OK because your charger circuit is more or less equivalent to our (unused) dryer circuit. And as others said above, you can adjust your maximum charging rate if you find there is a problem in the summer with the A/C on. (And I envy you, by the way. We have not yet been able to make arrangements to charge here. Our condo is a flat with no garage and no obvious way yet to provide charging. I am working on it with the condo board...)
  11. green1

    green1 Active Member

    Mar 25, 2014
    Calgary, Alberta, Canada
    Not a condo, but my house also has 100A service, I also have natural gas heat, stove, and hot water. Difference from OP is I have an electric dryer, but no AC
    Big electrical loads include:
    - Hot tub (50A breaker, doesn't seem to ever draw more than 30 though, even with startup surge from the pumps)
    - Tesla (50A breaker, stuck at 32A charging due to Tesla's new crippled Canadian UMC)
    - Dryer (30A breaker, unknown draw)
    No other loads over 15A, do have the furnace blower motor, fridge, microwave, dishwasher, washing machine, kettle, hair dryer, etc.

    No issues so far, and the electrician I talked to before wiring in the Tesla said there was no problem doing this.

    I'm considering getting a HPWC, but before I do that I'd probably upgrade to a 200A service entrance to allow for full 80A charging on my dual charger car.

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