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240v through the 5-15 plug?

Discussion in 'Model S: Battery & Charging' started by Electric Joe, Feb 2, 2017.

  1. Electric Joe

    Electric Joe Member

    Apr 15, 2015
    Howell, MI
    Does anyone know what happens if you use both flat prongs of the Tesla NEMA 5-15 plug adapter with hot wires to effectively send 240v through the UMC? I'm too chicken to try it. I figure the UMC might see the 240v and use it at up to 15 amps, or it might self-destruct because it was expecting only 120v since the 5-15 adapter was detected.

    I ask because I have access to a 240v low amp outlet at work and I'm wondering if I can make a simple adapter that the UMC's 5-15 would plug into.
  2. Sparky

    Sparky Member

    Aug 13, 2012
    #2 Sparky, Feb 2, 2017
    Last edited: Feb 2, 2017
    It sounds like you want a 6-15 adapter, which Tesla sells. If so, I recommend buying that.
    Then, you should be able to pull 12A at 240V.
    However, I've successfully used a Tesla NEMA 5-20 adapter (one sideways plug) in a 240V NEMA 240 20A outlet (6-20?). It was a garage outlet that has a whole-house vacuum which runs on 240V.
    The Tesla EVSE seems to only care about current limits for the particular adapter not the 120 or 240 voltage. I used the 5-20 since I couldn't get a 6-20 at the time and I wanted the current to limit at 16A max.
  3. davewill

    davewill Member

    Feb 5, 2014
    San Diego, CA, US
    It will work fine with the car pulling 12a @ 240V. The 6-15 adapter is available and would be better choice to accomplish the same thing. Some people use the 5-20 adapter at 240v as that is the only path to getting 16a @ 240v.
  4. Barry

    Barry Active Member

    Aug 9, 2013
    Bad idea to use a 5-15. Bad stuff can happen by accident. Reminds me of a trip to eastern Europe about 15 years ago where I saw the standard, round prong, 240VAC connector being used for headphones! :eek:
  5. SomeJoe7777

    SomeJoe7777 Marginally-Known Member

    Mar 28, 2015
    Houston, TX
    The UMC will have no problem with it, but 5-15 outlets aren't tested or rated for 240V. Could be a hazard. And it's not code-compliant, of course.

    Like others have said, better to use a 6-15 outlet and adapter.

    ⚡️ELECTROMAN⚡️ Fritterer and waster of hours in an off hand wayer

    Jul 15, 2016
    Portland, Oregon
    I would strongly suggest you get the proper adapter. They are only $45. It's not like the parts to build an adapter are free. I'm an electrician and I have the spare parts lying around collecting dust. I was going to make a 6-15 adapter that the 14-50 Tesla adapter can plug into. That way I can set the charging amperage to 12A for a 6-15 outlet and 16A if I'm plugging into a 6-20 outlet. I'm only making the adapter to have on hand for very rare occasions. That sounds a little sketchy to use the 5-15 for 240 volts, though. I would buy the proper adapter from Tesla if I was going to be using it on a daily basis. Especially if I was plugging into an outlet at work.
  7. miimura

    miimura Active Member

    Aug 21, 2013
    Los Altos, CA
    Overseas, I have seen regular 5-15 type outlets labeled as 240V and it frankly scares me. There is a reason that we have sockets that mechanically differentiate for voltage.

    Any home-made adapter that adapts one socket to another like 6-20 to 5-20 should be clearly labeled and kept in the car when not in use. Since there is a Tesla adapter for 6-15, it should be used with a proper 6-15 socket instead of re-wiring a 5-15 socket to 240V or using a third party or home-made adapter.
  8. n2mb_racing

    n2mb_racing Member

    Jun 14, 2014
    durham, NC
    Here you go, easiest option:
    Tesla — NEMA 6-15

    Though, you can get slightly faster charging (11 mi / hr vs 8 mi / hr) and about 3% higher charging efficiency by charging at 240V @ 16A using the NEMA 5-20 UMC adapter, but then you'd have to make a custom adapter.

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