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Electrician Saying 200 amps is maximum for residential in Los Angeles. Is that true?

Discussion in 'Model 3: Battery & Charging' started by Pkmmte, Oct 14, 2019.

  1. Pkmmte

    Pkmmte Le meow

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    So, I just bought a house earlier this year. Prior to that, I was charging for all of 2018 exclusively on superchargers. It's a very old house with an old 100 amp service panel located right next to the gas water heater (they almost touch).

    I want to upgrade my electric panel to at least 320 amps, but my electrician keeps insisting that 200 amps is the absolute maximum for a 1,200 square foot home like mine. You see, I have a Model 3, my wife has a Fiat 500e (soon to be replaced by another Tesla), my sister has an e-Golf, and my parents are considering a Model Y. That's 4 electric cars in total, or 240 amps if charging at the same time, just for the cars. Right now I'm charging my Tesla at work and superchargers, and my wife and sister take turns charging from a 120V outlet. It's extremely inconvenient.

    We've already installed the wiring for 3 NEMA 14-5 outlets (2 inside garage, 1 outside), and an exterior Tesla HPWC. All that's left is to connect them to the electric panel after upgrading it.

    We know a family electrician that flat out refuses to do anything more than a 200 amp panel, saying that 300 isn't a thing and 400 would require extra hurdles only for commercial properties. Is that true?

    I've gotten (MUCH more expensive) quotes from other electricians. Some of whom agree with him in that it's not possible, and others who say it's okay as long as I get explicit permission from the city. Does anyone have any experience with this?
     
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  2. jjrandorin

    jjrandorin Another BMW convert

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    Does your sister and your parents live with you? You really only need to consider the charging needs of those who LIVE with you, as you can always unplug one car to charge another "temporarily".

    FWIW my 3300 square foot home, with a 40 amp draw double oven, and 2 separate air conditioning units, built in 2006, has a 200 amp main service.
     
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  3. RayW

    RayW Joy Riding

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    I think they would have to run an additional service line from the street for more than 200amps
     
  4. Pkmmte

    Pkmmte Le meow

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    Yes, they all live with me.

    We already go through the inconvenience of taking turns plugging in, and that's before we even get our 4th EV. That's the issue I'm trying to resolve.

    We also have 2 separate air conditioning units and plan on getting an 80 amp electric tankless water heater.
     
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  5. SSedan

    SSedan Active Member

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    I can easily see 200amp being the cap on a modest sized house like that.
    For perspective my 1970s 2400sq house near Green Bay got by on a 200amp service 100% electric and that was resistance baseboard up till 3 years ago. Temps can get down to -25f here. 200amps is a lot.

    Put the Teslas on load sharing wall connectors, 100amp circuit up to 4 interconnected and as one finishes the others get more power.

    Anyone know how load sharing would work with wall connectors using adapters to connect to the non-tesla cars?

    Maybe install 14-30s to reduce total load.

    Unless everyone is a heavy commuter I doubt you need all cars pulling max amperage at once.
     
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  6. ucmndd

    ucmndd Active Member

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    #6 ucmndd, Oct 14, 2019
    Last edited: Oct 14, 2019
    The electricians you've spoken to are generally correct, residential service these days basically comes in multiples of 200 amps.

    That said, 400 amp service for a 1200sf home in a temperate climate is fully absurd, even with the loads you describe.

    For starters, I'm not sure how your math works. 4 EVs charging = 240 amps? No. Even if all four cars you describe are charging full-tilt at max amperage:

    Model 3: 48 amps max
    Model Y: Unknown but very likely 48 amps max
    500e: 30 amps max
    e-Golf: 30 amps max

    TOTAL: 156 amps

    Since you reference installing 14-50 outlets for one of the Teslas, not a second wall connector, that car is effectively limited to 32 amps (max the UMC will provide), so your real total as described is MAX 140 amps, not 240.

    Yes, that's a lot. But it's highly unlikely your house will be consuming another 40-60 amps overnight while you're charging. And if you dial each car down to say 24 amps or so, or schedule staggered charging, the extra overhead available is plenty to provide for any other reasonable house loads and still have everyone fully charged by morning.

    Since you're on 100 amp service right now I assume you also have natural gas? If so I'd seriously reconsider the electric tankless.


    From SCE's Electrical Service Requirements: https://www1.sce.com/nrc/aboutsce/regulatory/distributionmanuals/esr.pdf

    There's more here that may or may not apply - I'm not an electrician. So it seems like this might be technically possible, but I agree you're likely to encounter crazy expense and hurdles.


    If you really wanted to do this, you're likely best off looking at installing two meters/panels with two cable runs in from the street. One for the house, one for the EV charging. That will cost you a ton of money, but so will every other option you're looking at. That might be advantageous from a pricing perspective - not sure about SCE but PG&E has electric vehicle charging plans that provide cheaper rates if the EV circuits are on their own meter.

    Me? I'd squeak by on an upgraded 200 amp service. There's really no compelling reason you couldn't given the information presented.
     
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  7. Pkmmte

    Pkmmte Le meow

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    Thank you for the detailed answer.

    For some reason, I thought I needed 60 amps for each HPWC (I planned on installing 2 more after buying more Teslas) due to a 20% safety buffer I read about.

    I also have 2 air conditioning units and it's not uncommon for us to be using both late at night as I'm a bit of a night owl.

    That's not even accounting for all other appliances at home such as our 2 refrigerators and server I keep on at all times, let alone our 5 computers usually turned on. We're already tripping the breaker without charging any cars as is with our 100 amp service.

    I also remember one solar company telling us to keep 20 amps reserved for our potential solar installation.

    Looks like I'll have to tone down my expectations and electricity usage if 400 amps will be this much of a problem, though. I appreciate the reality check.
     
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  8. SSedan

    SSedan Active Member

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    The wall connectors you can put up to 4 on one circuit with one controlling the others and sharing a circuit. A three Tesla house is PRIME candidate for this, those cars can all share a circuit. Wall connectors also have a variety of amperage settings available from I think 12-80 with a bunch of options along the way. I would put in a 100amp circuit with 3 wall connectors, cars could share 80amps when they have to share and any of them could get maximum amps when needed. Yes the buy in of $1500 worth of wall connectors might give you sticker shock but this is what they are made for and will go a long ways towards making things work safely and efficiently for you. There are adapters to use Tesla connectors on other cars.
     
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  9. ucmndd

    ucmndd Active Member

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    You're correct RE the sizing of the wires and circuits, for exactly the safety buffer thing you reference, but what you're really concerned about here is actual load. HPWC wired on a 60 amp circuit will provide you 48 amps max to the car. Note that you don't size electrical load by adding up all of the breakers in your panel - you can (and very likely will) have more than 200 amps of cumulative circuits/breakers in a 200 amp panel.

    Portables I assume? A typical 10,000 BTU AC unit will use about 1kw of power, which is ~8 amps at 120v or 4 amps at 240v.
    120V fridges are ~3-5 amps when running (more than that when starting up). Typical home server maybe 5 amps assuming 500-600w draw.

    Individual breakers or the service mains?

    This is true, you need some panel capacity to add solar.

    I really do think 200 amps is more than enough, with just the smallest bit of thought and planning with respect to how you charge the cars (scheduling, amperage limits, etc).
     
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  10. jjrandorin

    jjrandorin Another BMW convert

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    Are you mis-quoting the size of your new house? I have never seen a 1200 Square foot house with 2 air conditioning units... unless you are talking about wall units and not central air?

    In any case, you might want to think about dialing down the charge amps for each of those EVs. its "nice" to be able to charge faster, but its likely not necessary for your daily usage. I would put both teslas on wall connectors with a shared circuit of 80 amps, and then split the other two on 30 amp circuits, and use scheduled charging to sort of stagger them if possible. You likely will be charging them all at night anyway because of time of use.
     
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  11. dhanson865

    dhanson865 Active Member

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    maybe it's 1200 sq foot per floor and it's 2 story and they don't realize it adds up?

    Two ACs (one per 1200 sq foot top floor and one per 1200 sq foot bottom floor) might make more sense.
     
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  12. ucmndd

    ucmndd Active Member

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    Given they say the house is "very old" and the square footage, I assume portable/window units.
     
  13. Obsoletion

    Obsoletion Member

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    Another option would be to install a second meter and panel just for EV charging.
     
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  14. dhrivnak

    dhrivnak Active Member

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    There is another way to skin the cat. You could be like me who has three NEMA 14-50 plugs in the garage for my 3 EV's. But it is VERY RARE I need to charge at full rate. One car is at 16 amps the other 2 are at 24 amps. Even at 24 amps I am alway full by morning. Just because you can charge at 48 amps is no reason to do so. The real question is what do you need? If you drive 60 miles a day then even at 24 amps you will be fully charged in 3 hours with a Model 3. Surely you sleep longer than 3 hours. Even if your average commute is 120 miles you would still be charged in 6 hours at 24 amps.

    PS my house is a much more challenging climate is 2600 sqft and our 200 amp service has never been an issue with our 3 EVs
     
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  15. Pkmmte

    Pkmmte Le meow

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    Central air for everything except the garage. We ended up installing a 10,000 BTU portable unit for the garage. We spend more time in there than we'd like to admit. (It doubles as an entertainment room when cars aren't parked in there)

    I appreciate your guidance. I'm a newbie when it comes to these things and figured I'd need 300 amps based on how often we're tripping our existing 100 amp service without charging 4 cars, and without additional miscellaneous electrical load we've yet to install.

    You've encouraged me to sit down and more carefully assess my needs.
     
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  16. Pkmmte

    Pkmmte Le meow

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    You're right, I could probably stick to a much lower charge rate for 90% of the time. I rent out my Model 3 on Turo and often find myself needing to charge a few hours before the next trip, thus my need for at least 1 HPWC.
     
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  17. dhrivnak

    dhrivnak Active Member

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    So if one is at 48 and the other two are 24 you are still below 100 amps, which should cover a 1200sqft home. If you have not done so go to all LED lighting. And if your garage is not insulated please do so, so you do not need to run that AC unit that much.
     
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  18. KJD

    KJD Supporting Member

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    Before you buy that tankless electric water heater you might want to read this thread.
    Tankless water heaters are terrible....
     
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  19. powaking

    powaking Member

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    Consider a mini split unit which would be more efficient and definitely rethink the electric tankless heater.

    Multiple HPWC can share the same circuit so there is balancing there instead of dedicated circuits. I think the max is 4 on a shared circuit.

    Also what is everyone’s daily mileage usage? Unless everyone is driving 200+ miles a day may be able to get by with charging every other day.
     
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  20. RKDauto

    RKDauto Member

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    I think you are going about this the wrong way. Why don't you just have the cars share a connection? The Tesla cars can share a connection using the Tesla wall chargers since the Tesla wall chargers are smart and will share the connection appropriately. Do you really need to charge all 4 cars at full speed at the same time? I don't know much about the VW eGolf. If you have 60 amp breaker and wiring and 2 or 3 wall connectors you can share the same connection for the Teslas. I have multiple properties with EV hookups. Generally, I just permit for a lower amperage, say 20 amps, 240 Volts but wire for 40 to 60 amps depending upon how I wish to set it up. Once the inspector is gone, I switch out the breaker. The NEC code always takes into account the worst case scenario which your house will never hit. To avoid going over 200 amps on the permit and creating a permitting headache, I just permit for a lower amp breaker. Personally, I would come up with a plan to live within the 200 amp panel you already have. I have a house with a tankless hot water heater, 50 amps, an A/C, a washer/dryer, cooker, and an EV hookup. By permitting for less amps, I was able to stay within the 200 amps.
     
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