TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

Changing a TT-30 to a 10-30 circuit

Discussion in 'Model X: Battery & Charging' started by beths11, Feb 15, 2017 at 9:48 AM.

  1. beths11

    beths11 THE LONG RANGER

    Joined:
    Apr 30, 2013
    Messages:
    393
    Location:
    Molalla, OR
    @islandbayy , @Cosmacelf , and @linkster and many others who may please jump in. I have found your electrical conversations very educational. I am hoping you can help me with what I believe is a simple question?

    I currently have a TT-30 outlet installed,(ground, neutral, hot). As we know it is a 120v/30amp circuit. I believe I can change it to a 10-30 for Tesla charging ONLY as Tesla does not use a neutral (hot, hot, ground). I would replace the single pole 30amp breaker with a 30amp double pole breaker. The black would connect to one leg, the neutral would now become hot and connect to the second leg, and the ground stays grounded. At the plug end I would connect the ground to ground, hot to hot and the old neutral now becomes hot. I have a Tesla 14-30 adapter (new, not recalled one) I would make an adapter which would have a 10-30 plug on one end and a 14-30 receptacle on the other end. The neutral connection on the 14-30 receptacle would have nothing connected to it. I can now plug in my Tesla 14-30 adapter and charge at 24 amps.

    Am I thinking correctly??
     
  2. BerTX

    BerTX Active Member

    Joined:
    May 2, 2014
    Messages:
    1,105
    Location:
    Texas/Washington
    I'm not an electrician. You should hire one.

    The NEMA 10-30 is not configured as you describe. It is an older outlet -- the 3rd pin is not a ground, but a neutral. Maybe a 6-30 would do what you want.

    Your logic is good otherwise, assuming your TT-30 has appropriately sized wire and you wrap both ends of the white wire with black tape to indicate its use.

    edit -- and clearly label your homemade adapter that it is for Tesla use only
     
  3. beths11

    beths11 THE LONG RANGER

    Joined:
    Apr 30, 2013
    Messages:
    393
    Location:
    Molalla, OR
    #3 beths11, Feb 15, 2017 at 11:27 AM
    Last edited: Feb 15, 2017 at 11:34 AM
    I understand the 10-30 has three connections, originally intended for Hot, Hot, neutral. Is there something that would prevent me from connecting a ground to the neutral pin since the Tesla does not need the neutral for charging? I would then have a 10-30 wired hot,hot ground(the ground connects to the neutral leg) which would connect, through and adapter to a 14-30 wired hot, hot, ground, no neutral connection (which the Tesla doesn't need).

    As they are both 30amp circuits(TT-30 and 10-30) the 10-2 wire size should be a non-issue
     
  4. BerTX

    BerTX Active Member

    Joined:
    May 2, 2014
    Messages:
    1,105
    Location:
    Texas/Washington
    Code.

    If you are going to illegally wire an outlet, change its use, and clearly label it for Tesla use only, then you might as well illegally wire a 14-30 outlet with no neutral and skip all the homemade adapter gradeaux.

    I thought your goal was to have a legal outlet, then build an adapter to connect to your 14-30.
     
    • Informative x 1
  5. beths11

    beths11 THE LONG RANGER

    Joined:
    Apr 30, 2013
    Messages:
    393
    Location:
    Molalla, OR
    No, a legal outlet is not my goal. A safe outlet, clearly labeled, to charge my car efficiently is the goal. The outlet is on a pole, at a RV pad, at a remote part of my property. It will be a TT-30 again when I sell the property.

    Thank you. Of course, I can skip the 10-30 plug and just install the 14-30 plug with no neutral.
     
    • Like x 1
  6. BerTX

    BerTX Active Member

    Joined:
    May 2, 2014
    Messages:
    1,105
    Location:
    Texas/Washington
    I deny saying you could do that. You must have misunderstood.:rolleyes:
     
    • Funny x 2
    • Like x 1
  7. KJD

    KJD Supporting Member

    Joined:
    Dec 14, 2013
    Messages:
    672
    Location:
    SLC, UT
  8. beths11

    beths11 THE LONG RANGER

    Joined:
    Apr 30, 2013
    Messages:
    393
    Location:
    Molalla, OR
    The problem is the circuit runs underground 3 feet and there is no way to put new wire in. I believe for a 50amp outlet 6 gauge wire is required Wire Gauge Tables
    What is currently run is 10 gauge. Sorry if I wasn't clear.
     
    • Informative x 1
  9. Rocky_H

    Rocky_H Active Member

    Joined:
    Feb 19, 2015
    Messages:
    1,026
    Location:
    Boise, ID
    I'll weigh in a little. @BerTX is giving good advice. You get to pick your poison, but your original suggestion was picking both poisons, which you don't need to do.

    (1) Wire the outlet fully to code, but have to use an adapter. In that case, you should just make it a 6-30, and then build a pigtail to use your Tesla 14-30 adapter.

    (2) As you said, if you're not worried about it meeting code, you can just put a 14-30 outlet on it directly with an empty neutral, and you can plug into it directly with the Tesla 14-30 plug and no intermediate adapter needed.
     
    • Informative x 1
  10. Cosmacelf

    Cosmacelf Active Member

    Joined:
    Mar 6, 2013
    Messages:
    3,479
    Location:
    San Diego
    Yes, you are correct, that will work, beths11. Instead of connecting the 10-30 neutral pin to ground, just connect it to neutral and it will thus be code. The Tesla adapter works find like that. Of course, you aren't supposed to wire a new 10-30 these days, but that's the only thing that isn't kosher.
     
  11. Cosmacelf

    Cosmacelf Active Member

    Joined:
    Mar 6, 2013
    Messages:
    3,479
    Location:
    San Diego
    Oh, yeah, since you are going to be using an adapter, wire in a 6-30 instead. 100% code.
     
  12. Cosmacelf

    Cosmacelf Active Member

    Joined:
    Mar 6, 2013
    Messages:
    3,479
    Location:
    San Diego
    The only thing I don't like about wiring in a 14-30 is that you might die of a heart attack and the new owner would get a surprise.
     
    • Funny x 1
  13. beths11

    beths11 THE LONG RANGER

    Joined:
    Apr 30, 2013
    Messages:
    393
    Location:
    Molalla, OR
    @Cosmacelf , thanks for the reply, I actually started thinking about this, and got your name from the thread on converting a 110/20a circuit to a 240v/20a cicuit Nema 6-20.. I feel silly not thinking to google nema 6-30 and do the same thing in 30amps...Of course, change the tt-30 to a 6-30 and make a 6-30 to 14-30 pigtail then use my tesla adapter.
    This is a much better solution
     
  14. Cosmacelf

    Cosmacelf Active Member

    Joined:
    Mar 6, 2013
    Messages:
    3,479
    Location:
    San Diego
    Oh, one more thing, when you convert a neutral to a hot wire, usually the neutral wire is white. It is a good idea to wrap black electrical tape around a segment of the white wire insulation at both ends (in the panel box and in the receptacle) thus signifying the conductor as hot.
     
    • Like x 2
  15. BerTX

    BerTX Active Member

    Joined:
    May 2, 2014
    Messages:
    1,105
    Location:
    Texas/Washington
    I don't think anybody thinks the 10-30 is the way to go and we've moved on, but this solution bothers me. I thought neutral would need to be the same size as the hot wires, and this sounds like cable that would have a smaller ground wire size. It also would be bare wire.
     
  16. davewill

    davewill Member

    Joined:
    Feb 5, 2014
    Messages:
    477
    Location:
    San Diego, CA, US
    Just a final nail in the coffin of the 10-30. In most jurisdictions, new 10-30 installations are not allowed anyway.
     

Share This Page