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6-30 or 14-30 charging on a subpanel with 30A breaker from main

Discussion in 'Model X: Battery & Charging' started by Birdcar, Jun 17, 2016.

  1. Birdcar

    Birdcar Member

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    I have a subpanel in the garage. it is powered by 4 #10 gauge wires from main panel. The distance is about 80 feet. The breaker size is 30 A from the main. Two questions:

    1: Is installing a 30 A capable socket (like 6-30 or 14-30) on a subpanel with 30A breaker from main violating any code ?

    2: Will 24A charging trip the breaker ? the rest of the electronics on that subpanel is less than 200 watts. I thought it will be OK, just want to verify
     
  2. KJD

    KJD Member

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  3. Birdcar

    Birdcar Member

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    Thanks for the pointer. it is an excellent document. But question 1 is not answered there.
     
  4. FlatSix911

    FlatSix911 918 Hybrid

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    I will let Flasher provide the definitive answer to your questions ... here is my 2 cents.
    Have an electrician evaluate your specific situation with load calcs if necessary. :cool:

     
  5. ccutrer

    ccutrer Member

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    1. No. It is quite common for the sum of the breakers in a sub panel to exceed the size of the breaker protecting that panel. A load calc determines the maximum probable load on a panel, and is what you size the panel for. Having a single (and continuous rated) circuit that matches the size of the panel is less common, but shouldn't put the kibosh on anything.
    2. I'm assuming those are 120V electronics? It depends on if they're on a single circuit, or on two circuits on opposite legs. If two circuits (or 240V!), that's 0.8A. If one circuit, that's 1.7A on one leg (with 0 on the other, but both legs will trip together). Technically, you'll be over on a load calc (which will be 24A plus the square footage of whatever this is serving), but just barely. Personally, I'd run with it, and if you get nuisance tripping dial down the car by an amp or two.
     
  6. Rocky_H

    Rocky_H Member

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    I see that @ccutrer addressed the electrical capacity issues, but I'll address this other issue that no one has mentioned yet. Putting in a 30A outlet type, like 6-30 or 14-30 will not be a very good idea, since Tesla does not offer any adapters for the charge cable that can use any of those. If you have the capacity to actually use 30A at 240V, you should put a wall connector on that circuit, not an outlet.
     
  7. ccutrer

    ccutrer Member

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    Good point. Did Tesla ever make a 6-30 (or even 6-50) adapter? I've been lucky enough to secure one of the discontinued 14-30s.
     
  8. TexasEV

    TexasEV Active Member

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    Tesla had a 6-50 adapter when the Model S was released. It was the first adapter to be discontinued. Probably because many 6-50 outlets are installed on circuits that are less than 50A-- that may be OK for welders but it's confusing and dangerous for Tesla owners.
     
  9. Birdcar

    Birdcar Member

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    Thanks everyone for pitching in. I finally installed a 6-20r from existing 5-20r sockets. No wires to pull, just rearrange the breakers in the subpanel. It works fine, charging at 10mph. This is the lowest cost solution for me.
     
  10. Rocky_H

    Rocky_H Member

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    Cool to hear. I think that’s a pretty good balance of a low cost easy install for a fairly decent charging speed. I am curious about what you are actually using to plug into it, since Tesla does not sell an official 6-20 adapter.

    They sell a 6-15, but that would be limited to 240V 12A, and I would think you want to get all the current you can from that circuit. So are you using a short adapter cord to use the official Tesla 5-20 UMC adapter to plug it into the 6-20? That would keep the car aware of the 20A limit and pull 16A max.
     
  11. HankLloydRight

    HankLloydRight Fluxing

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    What you describe in the OP is almost exactly the same setup I have. I have a detached garage about 30 feet from my house. I had an electrician dig a trench and run conduit and one 30amp line (with a 30 amp breaker in the main house panel) to a 30-amp sub-panel in the garage. That panel powers two 120v outlets, a couple of lights, and the garage door opener. I also have one 30-amp 14-30 outlet (on a 30 amp breaker) for charging my car. I built a very simple NEMA 14-30 to 14-50 adapter using @Cosmacelf 's great write up here:

    http://cosmacelf.net/Home%20Made%20Adapters.pdf

    I charge my car at [email protected] amps without any problems whatsoever.
     
  12. Birdcar

    Birdcar Member

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    I am using 5-20 Tesla adapter + a hand made adapter from 6-20p to 5-20r. The total cost is $45 + ~$30. The 5-20 tesla adapter will limit the current to 16A irrespective of the voltage.

    The good news is that it increases the charge efficiency from 80.0% to 85.6%. That will save me enough e-bill to pay for the parts in one year.
     
  13. Birdcar

    Birdcar Member

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    I thought a lot about doing the 14-30. since Tesla stopped selling any 30A adapter, I have to use what Hank described. eventually, I decided against it. It is a trade off between speed and low risk of tripping breaker. If the tesla resets and forgets about the current limit to 24A on the 14-50 adapter, the breaker may trip. My needs for 30A charging is really low as I was happy with 5-15 charging speed for about a month. What I really like is the higher efficiency at 240V.

    I also delay charging to early morning to shorten the time battery spent at high voltage.
     
  14. Rocky_H

    Rocky_H Member

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    Coolness. Not that you need it, but thumbs up from me--sounds like a pretty good setup.
     
  15. Electric700

    Electric700 Member

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    I thought I saw that some Tesla Service Centers have 14-30 adapters, or they are able to special order them. It might be worthwhile to call your nearest one if you're interested.
     
  16. Birdcar

    Birdcar Member

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    I called the ones in bay Area. none have them in store. I also saw posts sometime ago, but not lately. I sure do wish someone post the link if it is available. I like to buy one for road trip.
     
  17. FlatSix911

    FlatSix911 918 Hybrid

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    This has been mentioned before ... you can just mod your 14-50 plug for the 14-30 receptacle as recommended below.
    Keep in mind that you should reduce your amp setting to 24A on the Tesla display, and remember to check it regularly. :cool:

    upload_2016-7-9_10-32-59.png
     
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