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Help! Installing 14-30 outlet in garage

Discussion in 'Charging Standards and Infrastructure' started by jlawzy, Jul 10, 2018.

  1. jlawzy

    jlawzy Member

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    Hi everyone! I will be getting a Model 3 soon and now need to install an outlet for charging. My breaker box outside is on the opposite side of the house in relation to the garage so not possible to pull a line in from the outside. I have gotten a few quotes/opinions from electricians but have received somewhat differing opinions.

    The breaker outside that feeds the subpanel is rated 60 amps. I have two empty slots on the panel where every electrician says they can use both to pull 240v/30amps and terminating it in a new outlet. I had one electrician saying that he must upgrade the breaker to something more than 60 amps before he would proceed. The other 3 electricians say that it is not required and that I would most likely need to upgrade the wiring between the breaker and the subpanel first anyway if I really wanted to do that.

    I've attached pics here and hope to get a knowledgeable opinion to move forward! Do you guys think I would be fine to leave the 60 amp breaker as is and moving forward with creating a 30 amp line out of the subpanel?

    THANKS!
     

    Attached Files:

  2. ewoodrick

    ewoodrick Active Member

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    If the beige panel is the subpanel, then you definitely aren't going to put it there. All of those circuits are on a 60A circuit and, to me, look a little overloaded already. If you put it here and it trips the subpanel breaker, then your house shuts off, except for drier and oven.
    Assuming that the gray box is the main panel, that's the only place where I would place it.
     
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  3. jlawzy

    jlawzy Member

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    that is what my gut tells me but i have 3 electricians who tell me it should be fine lol
     
  4. boaterva

    boaterva Supporting Member

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    You've got, what, 25 or so breakers on a 60 Amp subpanel, already, and you want to add a continuous draw of 24 Amps?! First, you aren't pulling 30, you are pulling 24. It's a 30 amp circuit, so, you can only pull 80% continuous (see my sig for Flasher's excellent FAQ on this and a lot more). But the general answer looking at that subpanel is: :eek:

    I don't know how it works NOW, never mind wanted to add a 24 Amp load (even if say you lower it to 20 or something, which gets to, not even worth it).

    I'd put a separate circuit 'somewhere else' (yeah, I know, easy for me to say!).

    Unless you know there is no one in the house using any of those 'household' circuits while you are charging!

    This makes no sense.

    I think I'll be an electrician. It has to be easier than Computer Virtualization. Because this is stupid. :D

    (I also have a degree in Electrical Engineering, just to show I'm not making this all up.... :cool: )
     
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  5. Rocky_H

    Rocky_H Active Member

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    That setup blows my mind! I also have an electrical engineering degree, but it's in doing layout for computer chips, not house wiring.
    Yeah, there are 30 single pole breakers in that subpanel, which add together to 530 amps, that is being fed from a 60 amp breaker from the main panel!!! You're obviously allowed to oversubscribe somewhat, because it's known that you don't have all of the lights on and all of your appliances plugged into every outlet in the house turned on at once, but that looks...questionable. It sure would look like it needs a load calculation before I would touch anything in there. I would be scared to add any more load to that subpanel that's only supplied by a 60A line.

    But on that main panel, it's a 200A main breaker, which is fairly significant. I only have a 125A main, but I was able to add a 50A in there. NEC does allow for "non-concurrent loads" in the load calculations. So for instance, you're not going to be cooking dinner from 1AM to 5AM or probably not running your dryer at that time. So you are allowed to pair up two loads that will be used a different times, like the oven and car charging circuit, and only count the larger of the two, because they won't draw at the same time (probably).

    So to sum that up, you could probably add a 40 or 50A circuit to that main panel, which would be time-offset with the oven, and it would still fit within the same load calculated capacity.
     
  6. boaterva

    boaterva Supporting Member

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    Right, adding this or a larger charging circuit to the main panel would probably work fine. To the sub? No way. I’m not sure what the ‘electricians’ are thinking. Besides none of the other loads are being used, add one more?
     
  7. jlawzy

    jlawzy Member

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    the problem i think with my house layout is that the main breaker sits on the opposite side of the house relative to where the garage is. it is a two story house and above the garage is a bedroom. i believe the way to pull a new 50a circuit would be to run conduit up the side, across the attic somehow, down the other side, and punch a hole in the brick there to terminate a 14-50 outlet in the garage.

    there was one electrician who said he would upgrade the 60a breaker to something higher first - 70-90, then he would feel comfortable with adding another 30a to that subpanel.

    so basically, a few electricians (and these are master electricians) have said it should work fine as is. 1 said he'd upgrade the 60a breaker first, then use the sub-panel. and then of course 1 that said that subpanel may trip and he prefers to run a new dedicated circuit off the main line but then he saw the house and stopped communication lol.
     
  8. Rocky_H

    Rocky_H Active Member

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    Well, money can fix everything. It's just going to be expensive because it's a long, difficult run.
    I don't know the details of what the load calculation looks like for that subpanel and your house's size and use, so maybe running the numbers does show that it works. I like the upgrading the feed to it, though. But yeah, the sight of it just freaks me out, without knowing what the calculation of it is.
     
  9. eprosenx

    eprosenx Active Member

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    So lots of thoughts here:

    1. I wonder if there is any chance that the remote panel is fed from "lugs" on the bottom of the main panel and that 60a breaker is for some other sub panel? Unlikely, but it is just a thought (if that was the case then the subpanel may be good for a full 200a - protected by the main 200a breaker). It is common to have an outdoor panel with just a handful of breakers but that feeds a full 200a through to an indoor panel (but I don't think this is that).

    2. Are you comfortable taking the panel covers off and taking lots of detailed pictures? I am wondering what type (copper or aluminum) the wire is, what wire gauge, and what wire type it is (in conduit or not, NM, SE, etc...) This would tell us something about if a higher amperage breaker would be allowed. Odds are the 60a breaker is the max for whatever they ran, but who knows, it could be that you would just need to upsize the breaker and the existing wire would be fine. I fear they may have just use 6 AWG copper SE cable and perhaps they used the 75c insulation rating (which I think used to be allowed in NEC, but now they may have moved it down to match the 60c limit of NM cable), or they used 6 AWG NM wire at the 60c rating which is 55a and then used the "next size up" breaker rule which allowed the 60a breaker even though the wire is only rated for 55a.

    3. That is a *ton* of circuits off a 60a feed, though as others have pointed out, the total addition of all the circuit values does not matter. What matters is the load calculation formula. However, I find it hard to believe that you would have another 30 amps (24 amps) of continuous load capacity available. That is half of your 60a... (you must use the 30a number, not the 24a) Unless you can make some argument about non-concurrent loads in the calculation, however, that might be questionable. I could make an argument for having one plug in my garage and one outside for my car (depending on parking location) but that I only would ever use one of them, though the inspector could also say that the next owner might have two electric cars and not realize the limitation. I would not really feel comfortable trusting a human to every time set the car to charge in the middle of the night only.

    4. If you do use this subpanel with this 60a limitation, you might consider getting a Wall Connector which you can set limits on pretty granularly if you find you only have 16a of capacity remaining on that subpanel, etc... You could also start out with a low setting and if you found you needed more, then pay to have the subpanel feeder upgraded and just crank up the wall connector (use sufficient gauge wire from the wall connector to the subpanel and a big enough breaker on day one to allow for this to be cranked up later).

    5. As discussed, you could run a dedicated run back to the main electrical panel and bypass the subpanel altogether. If you don't have any issues with the subpanel right now then avoiding it altogether may not be a horrible idea (less connections and less things to go wrong).

    6. This may not meet code depending on the load calcs, but you could try it out and see how things go. i.e. wire it up and see if it works. In theory the worst case is that you blow the 60a breaker, though the more I think of it, that removes one layer of safety (the load calculations) so I can not recommend it. Breakers can malfunction. If you did go this route, I would replace the 60a breaker to the sub panel probably with a brand new one to limit risk as much as possible. They are like $10 for most manufacturers. An even better option may be to buy a Sense Energy Monitor and gather some real world data on how much your house actually draws. If you thought you might upgrade the feed to that panel later I might do the wire to my receptacle or Wall Connector from that panel with thick enough wire to support a 14-50 or 60 amps to a wall connector (so you can max the M3 at 48 amps). So even if you crank down the wall connector in the short term or just install a 14-30 receptacle, you could later upgrade it trivially with a different breaker and receptacle in the case of a 14-30, or just a different setting in the case of a wall connector. Heck, you could even install a 14-50 on a 50a breaker in the subpanel and just rely on manually cranking it down EVERY time you charge, but this would NOT meet NEC and would be a risk. You are still protected by the 60a subpanel feed breaker, but again, you are not supposed to trust that.

    Please report back! I am curious to see what you end up doing!
     

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