Adding a 60 amp sub panel

solar_dave
solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
in Energy Use & Conservation #1
I am getting ready to add a EV charger in my garage, in planning ahead I am considering running a 60 amp sub panel in the garage to add two 240v 20 amp EV chargers and a coupe of dedicated 120v 20 amp outlets.

The question is I have a 200 amp main panel derated with a 175 amp main breaker, the only things on that panel are a 100 amp sub-panel feed for my new building and a 60 amp back feed breaker for the solar system. Can I add a 60 amp sub-panel feed to this main panel for a garage line?

I think that is about the limit for that panel then? 100 + 60 amp load and 60 amp back feed. Am I wrong?
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  • niel
    niel Solar Expert Posts: 10,300 ✭✭✭✭
    #2
    Re: Adding a 60 amp sub panel

    if i read you right then i agree it is correct. the 160a in loads won't bother the 175a breaker and with another 60a present from the solar then that puts the bus up to 220a and you are allowed up to 240a. you could still expand and use another 20a at 220vac in the main panel legally, but because of the main breaker being at 175a it will allow another 15a at 220vac.:D
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #3
    Re: Adding a 60 amp sub panel

    Thanks Neil, I thought I had it right but you guys are so knowledgeable it never hurts to check. Also I like having the confirmation before I talk to the electrician.
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  • Jburgess
    Jburgess Solar Expert Posts: 130 ✭✭✭
    #4
    Re: Adding a 60 amp sub panel

    Be sure to read article 625 in the NEC for disconect, ventalation and mounting hieght requirements.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #5
    Re: Adding a 60 amp sub panel
    Jburgess wrote: »
    Be sure to read article 625 in the NEC for disconect, ventalation and mounting hieght requirements.

    Well to add the sub panel and the charger will require a permit, I am sure the electrician will need to know the requirements. I think the volt batteries are sealed so ventilation is not a concern.

    Thanks for the particular NEC code requirement.
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  • dwh
    dwh Solar Expert Posts: 1,341 ✭✭✭
    #6
    Re: Adding a 60 amp sub panel

    You need to differentiate between "supply" and "load". (The caps are just for emphasis - I'm not yelling. :D )

    You have a 200a rated panel (200a rated bus bars).

    You can have UP TO 120% of the panel's rating in SUPPLY breakers connected to those bus bars.

    You can have UP TO 125% of the panel's rating in LOAD breakers connected to those bus bars (for residential - not allowed for commercial).

    That's 240a worth of SUPPLY breakers -and- 250a worth of LOAD breakers at the same time - it's not an either/or situation.

    Right now, you've got 175a + 60a = 235a of SUPPLY breakers connected. No problem, but you can't connect more SUPPLY to that panel.

    You've got 100a worth of LOAD breakers connected. You could add up to another 150a worth of LOAD breakers to that panel.
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  • solar_dave
    solar_dave Solar Expert Posts: 2,397 ✭✭✭✭
    #7
    Re: Adding a 60 amp sub panel

    OK I just need to add load breakers for a 60 amp sub panel.
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