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Would someone mind helping me understand this wall charger install quote?

Discussion in 'Model 3' started by psykobunny83, Jul 23, 2018.

  1. psykobunny83

    psykobunny83 Member

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    Hi everyone,

    Here's a photo of my breaker: Imgur

    I just got a quote from the first place here in Toronto to have the wall charger installed, but noticed they wrote on the quote:

    - All necessary wiring (approx 90’) suitable for 48A charge rate should panel be upgraded in future.
    - Double Pole 60A Breaker / 36A Charge Rate

    Would someone mind helping me break down what that means? It sounds like I wouldn't get the maximum charge supported based on their comments, but when they say "should panel be upgraded in future" are they referring to the circuit breaker? Where would I fall in terms of the max charge rate? Trying to determine if getting a new breaker or panel would be worth it or if the charging rate I'd get is going to be pretty high still? I drive very little, maybe 10-20km a day if that as I work from home, so I don't really need the absolute highest speed, but if it's not too much more to upgrade it all then I'd look into it. Thanks!
     
  2. SageBrush

    SageBrush 2018: Drain the Sewer

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    #2 SageBrush, Jul 23, 2018
    Last edited: Jul 23, 2018
    That confuses me too.
    A 60A breaker supports 48A (60*0.8) continuous, or so I thought.

    As for speed, each 16A works out to ~ 15 miles (24 km) of charge an hour in the Model 3.
    90 feet is a long run, so you may want to consider a lesser rated wire to save money.
     
  3. mongo

    mongo Well-Known Member

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    They are running thicker (lower gauge) wire to allow a higher charge rate ins the future if you upgrade your main panel and service to 200A. Wire is only a small part of the cost of installation, so not a bad idea. The larger wire also helps with the run length.
    Are you having a HPWC installed?
    Sounds like 36 amp (8.6 kW) would be plenty for you. Full charge overnight (~10 hours or so).
     
  4. psykobunny83

    psykobunny83 Member

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  5. Ejl80

    Ejl80 Supporting Member

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    Yes, they are telling you they are installing the proper wiring for a 60A breaker (48A charging), but your 100A panel really can't support such loads with the rest of your loads.
     
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  6. mongo

    mongo Well-Known Member

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    Yep!
    I used the old name (High Power Wall Connecter).
     
  7. psykobunny83

    psykobunny83 Member

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    Thanks so much everyone!!!
     
  8. m4eyyz

    m4eyyz Member

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    I'm not an electrician by any means (but I've hired a couple). That looks like a 100a panel - and you've got a lot of load already.
    Wouldn't they need to put in a lower rated breaker than a 60a breaker?

    Any electricians care to educate me?
     
  9. mongo

    mongo Well-Known Member

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    The breaker protects the wire, so if the wire is large enough it's good there. The WC is configurable as to the max current it will draw, so that will be set based on available panel capacity. Only thing a smaller breaker would do is trip if the WC was set incorrectly.
     
  10. eSpiritIV

    eSpiritIV Member

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    #10 eSpiritIV, Jul 23, 2018
    Last edited: Jul 23, 2018
    Yes they are installing thicker gauge wire apparently. It is a long run though. You might have voltage drop issues, so have them provide a voltage drop calculation so that they show that a fully loaded wire will not overheat. If they dont know what you are talking about then find another electrician.

    Have them quote both a 50A and 60A wire size though (The actual size used, and make it Copper not Aluminium) .You should compare what it will cost you for the standard install vs full capacity install. They are basically going to buy a 100ft spool of wire for your 90ft run and charge you for the full roll.

    In reality many people are just fine with a 32 amp charge rate (50A breaker) because they charge overnight. Only if you drive a TON daily would you need to charge at home and then leave on a big trip.

    For myself i installed a 50A breaker and wire for a NEMA 14-50 plug, then later installed a HPWC at 32A. The HWPC is mostly for convenience so you dont have to use your mobile charger.
     
  11. psykobunny83

    psykobunny83 Member

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    Thanks I'll ask them. They were the first one listed under the Tesla recommended electricians so hoping they are good then!
     
  12. mongo

    mongo Well-Known Member

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    Minor quibble: voltage drop and wire heater are two separate things. The gauge is tied to the max current (heating), but can be increased to reduce the voltage drop.

    If using conduit, they will be running 2 black and a green. With NM-B they can use 2+G (white, black and copper ground). In either case an electrician will likely either be starting with a larger spool than 100 foot or buy the wire to length from their supplier.

    A 32 Amp charge rate would only need a 40A circuit.
    US prices for reference (note: ground can likely be smaller to save a little).
    40 Amp is 8 AWG in THWN @ $0.26 a foot *3 = $0.78 a ft $70.20 for 90 ft, or $0.97 in NM-B
    50 Amp is 6 AWG in THWN @ $0.57 a foot *3 = $1.71 a ft, $153.90 total for 90 ft plus conduit or $1.32 a foot for NM-B, minimal conduit (only where exposed)
    60 Amp is 4 AWG in THWN @ $0.81 a foot *3 = $2.43 a ft , $218.70 total + conduit
     
  13. psykobunny83

    psykobunny83 Member

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    It basically worked out to $1650 for all noted above, plus $79 for ESA permit and inspection, plus $224.77 tax, total $1953.77 so seemed in line with what I expected.
     
  14. SageBrush

    SageBrush 2018: Drain the Sewer

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    #14 SageBrush, Jul 23, 2018
    Last edited: Jul 23, 2018
    How does that work in practice, other than the main breaker tripping if over 100A load is present ?
    If total load is under 100A, would the car charge at 48A ?
     
  15. aydyn

    aydyn Member

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    The bottom line is your home's 'service' is only 220/100A. This is much too small for the loads you have, while you have him working on your house have him upgrade your homes service to 200A. You are going to need to do so anyway very very soon. You already have 300A worth of breakers, I'm kind of surprised code allows you to add another 60A breaker to that panel.
     
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  16. aydyn

    aydyn Member

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    No he would dial the dip switches on the charger to limit it to 36A rate, and this is a smart move on his part given the OP electrical setup.
     
    • Informative x 1
  17. mongo

    mongo Well-Known Member

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    That is not how a load calculation works. (Though some panels do limit total breaker ampacity per bus).
     
  18. SageBrush

    SageBrush 2018: Drain the Sewer

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    I've been curious about that, since it must be impossible to know when loads will be active.

    May I ask for the abridged, dummies version ?
     
  19. mongo

    mongo Well-Known Member

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  20. SageBrush

    SageBrush 2018: Drain the Sewer

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