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Adding a 60 amp circuit for a HPWC. 200 amp service.

Discussion in 'Charging Standards and Infrastructure' started by Webeevdrivers, May 21, 2018.

  1. Webeevdrivers

    Webeevdrivers Member

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    Hi all. Our province has an incentive for installing a permanent EVSE so we are considering adding a Tesla HPWC on a 60 amp circuit. Here’s the thing. We have a 200 amp service and we already have a 40 amp breaker powering our Juice Box on a 14-50 receptacle. Also an electric stove. Also a central AC. Soooo, how much can we put on the 200 amp panel before we have to give up the juice box. We would like to have them both. We are a two EV family and there is more than likely a Tesla in our future.

    Yes we are having an electrician coming to do the install as per the program requirements. Just trying to get a feel for what he is going to say.

    Thanks in advance.
     
  2. Not1Drop

    Not1Drop Member

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    We put the HPWC on a 100 amp circuit so it maxs at 80 amps, back in March of this year. So much better than the 32 amps off the 40 amp 14-50 we used before.
    The electrician will give you the proper answer based on your service. however you basically would have 160 amps of useable from the 200 amps of service. Will be interesting to see how long it takes to receive your rebate for the install and hpwc, we're just passing two months now.
    For us we're geothermal for heat and ac, there was no issue running the heat, charging the car at 80 amps, boiling water on the stove and throwing a load of laundry in the dryer. Basically where our electrician warned us to be careful with maxing the load would be when i mentioned we'd eventually have a second EV as the reason why i wanted to leave the 40 amp connected in the garage. So he wisely pointed out that that would mean having two ev's charging at the same time would draw 120 of our useable 160, so then there could be an issue that will result in a very loud bang and no power.
    As it stands when the time comes, now that the HPWC is topping us up so quickly we could easily charge one, then charge another starting the charge for one at 7 pm, then the slower after 11 or 12 for example.
    Other parts of the install to consider is that changing to a higher amperage may require a heavier gauge wire than what you're using for the 14-50 plug = cost. There may also need to be a separate switch\breaker in the garage to turn off the power if necessary, again depending on the amperage. Inspection fee was included and I would happily recommend our electrician if you're in York region.
     
  3. Lloyd

    Lloyd Well-Known Member

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    You will have to do a load analysis to answer your question. If you charge at night when other demands are low, you will likely be ok.
     
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  4. Webeevdrivers

    Webeevdrivers Member

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    Thanks for the reply’s. One of the vehicles will be our leaf so max at 27 amps but it is on that existing 40 amp circuit. I’m not a Tesla owner so excuse the ignorance but the Tesla we get will probably be a long range model 3. Correct me if I’m wrong but I think the max charge rate on an HPWC for that car is 48 amps. Is that correct?

    Right now the second vehicle is our smart ED which we actually quite often charge on our 120 volt EVSE.
     
  5. Rocky_H

    Rocky_H Active Member

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    You can't get a real answer for that over the internet from us. You will need to get a load calculation that is very specific to your house and how many rooms, square footage, what appliances, etc. you have. A load calculation does have a "non concurrent load" provision that you can use, where you can assign two large-ish loads as being totally different time periods for their use. So you can take the 40A or 50A circuit for your oven and say you are not going to be doing any cooking after 1AM, and that will be offset with the new 60A circuit for the Tesla wall connector if you are only going to use that after 1AM. Then, instead of having to add 40 + 60 to the total, you can count only the larger of the two, so it doesn't increase the total as much. I only have a 125A total service, but I was able to put in a 50A circuit, because I'm not going to be using my electric dryer or oven after 1AM.
     
  6. Webeevdrivers

    Webeevdrivers Member

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    Thanks for the reply’s guys. I think I have a game plan.
     
  7. Big Dog

    Big Dog Member

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    yes, the M3 LR has a max of 48 amps, so a 60 will do it.

    fwiw: if you do become a 2-TSLA family, you can put two tesla wall chargers on the same 60 amp circuit and connect them in series (?) so they will charge, one after the other.
     
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  8. scottm

    scottm Active Member

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    #8 scottm, May 23, 2018
    Last edited: May 23, 2018
    After having owned electric for a few years now, I advise people that wiring for a Nema 15-40 is a sufficient in the garage for most driving needs of a Tesla. You can use a 40A or 50A breaker for that with matched wiring to draw 32A or 40A loads (respectively) - you'd choose depending on what your charge equipment can pull. These days UMC are 32A so a 40A breaker ... just like a stove. In my case, 50A breaker with correct wiring sustains 40A which is what my portable UMC draws. (It's older style higher power).

    I have both a Nema outlet and a HPWC hanging off a 100A subpanel in my garage. The HPWC is on a 100A breaker and device is set to 80A because that's what my dual on-board chargers can absorb in model S when maxed out. The Nema 15-40 is on a 50A breaker and is hanging on the outside wall there for EVisitors (plugshare'd if you need a hit - I'm on the outskirts of town, so first charger to be reached coming in from the highway - handy location for a desperate need).

    We wouldn't ever see both chargers being used at the same time, but if they accidentally are used simultaneously that's what a chain of 100A breakers will take care of (200A main panel in house has 100A branch breaker to garage subpanel, the garage subpanel has a 100A panel breaker at the top, and another 100A breaker for branch to HPWC, and a 50A branch breaker to Nema outlet.

    Upgrading my lot service from 100A to 200A and adding a subpanel in garage had a new infrastructure cost of around $8000 to support 80A charging in my garage. It's "nice" to have this kind of capacity and I depended on it heavily for first couple years but I seldom charge at home any more... so kinda wasted now. I charge at work and places I visit (IKEA, Canadian Tire, MEC, Peavey Mart, Supercharger @ mall, etc..) all for free. It's not hard to keep the car between 20% and 70% all week charging here and there. Weekends I sometimes charge at home.

    Anyway, I've now got 100A in the garage for any purpose... which on an acreage is a bit of a selling point, to support a welder, air compressor, shop tools...
     
  9. brkaus

    brkaus Active Member

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    Slight correction per my understanding. They are not actually hooked in series, the wire needs to be split/branched somewhere. And it will charge both at once, splitting the available power (until one is full then the other will get all the power).
     
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  10. Big Earl

    Big Earl Supporting Member

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    That isn’t quite how it works. You can connect multiple wall connectors to the same circuit (up to 4) and they will share the available power evenly across all of the units.

    For example, if you hook two wall connectors up to a 100 amp circuit breaker, each wall connector will do up to 80 amps individually or 40 amps each when both are charging two cars simultaneously. Four wall connectors on a 100 amp circuit would provide 20 amps each with four vehicles charging simultaneously while still providing the full 80 amps if only one vehicle is charging.

    This load sharing arrangement is a great option for homes and business with limited electrical service. It also reduces the amount of wiring required, saving some money on installation.
     
  11. scottm

    scottm Active Member

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    Worth pointing out the load sharing is done only by Tesla HPWC that are so-equipped. The newer ones are. The older HPWC are not.

    We are about to become a 2 Tesla family, and will either cord share the existing HPWC or get a second newer HPWC in slightly more convenient location for 2nd car.. but these would not talk to each other and load split. We'd still have to manually be careful who's drawing what when.

    The 2nd HPWC is really not needed, but would be handy as a redundant charger if one were to fail.
     
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  12. eprosenx

    eprosenx Active Member

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    You could get the second HPWC and just crank down the allowed amps (setting inside HPWC) on both units to some amount of power that would not endanger overloading your main electrical service. If your daily driving needs are not too huge even a much lower charge rate on the HPWC may be just fine. You could set one to be the "fast" charger and one to be the "slow" charger and park the cars as appropriate for a given day to give the higher power charger to the more needy car.

    But yeah, optimally you would get two of the newer model HPWC units and have them talk to each other...
     
  13. scottm

    scottm Active Member

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    I hardly charge at home any more, so ... I can't see getting fancy with dual communicating HPWC.

    My wife will probably charge at home more, so she'll take the prime spot closer to the HPWC. And I'll just borrow the cable if/when I might need a kick at home.
     

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