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60 Amps vs. 80 Amps

Discussion in 'Model 3: Battery & Charging' started by TheRealM3, Apr 5, 2018.

  1. TheRealM3

    TheRealM3 Member

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    I am getting some quotes to install HPWC but I am a bit confused (I don't know much about electrical stuff).

    My home services is 200A.

    One guy suggested 80 amp line with a disconnect switch.

    Another guy suggested 60 amp line without a disconnect switch (I read in another post that a disconnect switch is not required if 60 amp and below). He said anything higher will cause issues and may trip the circuit breaker since I have other things that use electricity.

    What is better? I want to future proof but also don't want the Tesla wiring to cause any issues.
     
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  2. Hans L

    Hans L Member

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    Go with an 80 amp line for future proof reasons. The NEMA 14-50 plug is only good for 32 amp draw. With the 80 amp breaker, you could potentially charge 2 Tesla M3's with Wall Chargers. I installed 100 amp just to be sure in my garage. I only have the NEMA 14-50 plug for now - charges at 28 mph. Per Tesla, the Wall Charger, rated at 40 amps will charge between 37-44 mph.
     
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  3. cmaster

    cmaster Member

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    It's cheaper to run aluminum from the breaker panel to the disconnect switch. And use copper from the disconnect switch to the HPWC. I'd go with 90 amp circuit breaker with SER #2 Aluminum to disconnect (100 amp disconnect). Then from the 100 amp disconnect to the HPWC using #4 copper. Set the HPWC to 72 amp draw.

    I also have a 200 amp service panel.

    (BTW - the 100 amp disconnect Switch can be found from eBay for 50 USD as oppose to a retailer like Home Depot for 155 USD)
     
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  4. oktane

    oktane Active Member

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    20 Amps
     
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  5. oktane

    oktane Active Member

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    Huh? Actually a NEMA 14-50 outlet is good up to a 50A draw, as referenced in the name. However, continuous draw should be limited to 80% of maximum, or 40A. A 50A circuit breaker should be installed.
     
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  6. TexasEV

    TexasEV Well-Known Member

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    The generation 2 UMC only draws 32A when plugged into a NEMA 14-50. If you want more than 32A now you need to use a HPWC.
     
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  7. oktane

    oktane Active Member

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    Ahh so Hans meant the UMC was limited to 32A not the NEMA 14-50 outlet...... gotcha now ;)
     
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  8. MosquitoFloss

    MosquitoFloss Member

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    The charging tables that come with the Wall Connector show no speed increase in M3 charging after 60Amps. There is future-proofing and all that, but I just went w 60A going directly to the Tesla Wall Connector (via garage sub-panel). In LA there is a $500 rebate for new wall charger installation, so this seemed like a no-brainer over the 14-50 scenario. I can leave my chargers in the trunk and probably never use them. Now if a VIN would just arrive today I can stop staring at this lonely new charger!
     
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  9. Hans L

    Hans L Member

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    Yes - that's what I meant :)
     
  10. Shygar

    Shygar Member

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    I installed a 60amp HPWC and am using the full 48 amps from the car (about 11 kWh). I also thought about future proofing it but it was going to be a good bit more to do that and in reality I can do that later if I really need. All depends on how much power you really need to charge. Are you doing a lot of driving everyday?
     
  11. FlyF4

    FlyF4 Son of a MX

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    I guess you know that whether or not a disconnect switch is needed will be determined by local building codes, so hopefully your electrician gave you the right info. If in doubt, call and ask a building inspector. It wouldn't be the first time that an electrician wants to sell you service for something you don't need.

    Maybe I overlooked it, but I did not see the limitation of the car you will be charging. Makes no sense to go from 60 to 80 if your car can't even use 60. And then think about how quickly do you really need to charge the car anyway? Even at a low charge rate, you can get a full charge over night.
     
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  12. Shygar

    Shygar Member

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    If it matters, I just called PG&E to switch to the EV-A rate and looks like they want to do a load check on the transformer based on me drawing from a 60amp breaker. Just FYI in case you decide to go big, you may want to double check with your power company to make sure you are ok.
     
  13. TheRealM3

    TheRealM3 Member

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    Thank you for all the information. It looks like there is no real right or wrong answer. I will ponder, get more estimates and go with someone that I am comfortable with.
     
  14. mattreidy

    mattreidy Member

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    I use a 50A 220V circuit and my Model S draws 40A at 220V with a generic NEMA 14-50 outlet. Cost me less than $100 to install.
     
  15. TexasEV

    TexasEV Well-Known Member

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    You mean 240V.
     
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  16. animorph

    animorph Active Member

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    There is a right answer to your maximum allowable current. You need to do a load calculation, or have an electrician perform one for you. That will tell you the maximum amps you can safely pull for your new circuit. The two guys who quoted should have done a load calc and told you the results.

    I went with 100A as the cost wasn't that much more and I wanted to charge two cars in the near future. I think 60A would still be more than enough, even with two cars, unless you are running a taxi service. Tesla says the charge time for an X at 48A is 10 hours for 300 miles of charge. Any other car will be faster, and you probably won't be charging from 0% to 100% daily. Is that fast enough to charge two cars overnight with your worst case future usage?
     
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  17. brkaus

    brkaus Well-Known Member

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    How many miles do you expect to drive a day?

    Do you have an extenuating circumstances, like frequently return from long road trips and need a quick turn around (like an ER doc).

    I have an S100D. I put in an HPWC on a 50A circuit (I get a better electric rate at 40a or lower). It meets my needs just fine. I drive 50~80 miles a day. I charge every night, or every third night if I forget.

    Every morning (I remember to plug in) it is fully charged and that is with 50A circuit - 40A charging. I even typically set it down to 30a.

    Get some quotes. 60A shouldn't cost much more than 40A. If 80-100a is not much more, go for it. Personally, if it cost a lot more, i wouldn't bother.

    If you add another HPWC later, you can deal with it later.
     
  18. brkaus

    brkaus Well-Known Member

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    BTW - the cheapest disconnect for 60a or less is the blade style disconnect typically used for HVAC units. Less than $10. For higher, a small sub-panel is frequently the lowest cost.
     
  19. timk225

    timk225 Active Member

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    Or get a Gen 1 UMC from a Model S that will draw 40 amps?
     
  20. Jackl1956

    Jackl1956 Active Member

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    It depends on the “authority having jurisdiction”. In a nutshell building codes, and electrical codes are national, statewide and local. In addition, your utility company may have jurisdiction depending on your metering configuration. Those things said, a licensed electrician should pull an electrical permit and ensure the installation complies to all applicable codes and requirements.
     

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