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How to tell NEMA 10-50 from 10-20?

Discussion in 'Charging Standards and Infrastructure' started by RDoc, Oct 19, 2013.

  1. RDoc

    RDoc S85D

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    We're in a rental house we go to every year that has an electric dryer on a circuit with a 240 30A breaker. The plug is a 3 bladed one, all straight, but I don't know if it's a 10-50 (scary) or a 10-20 (weird).

    It's there a simple way to tell them apart?
     
  2. qwk

    qwk Model S P2681

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    No such thing as a 10-20. If it has 3 flat prongs, and is 240V, it sounds like a 10-50.
     
  3. scottf200

    scottf200 Active Member

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    #3 scottf200, Oct 19, 2013
    Last edited: Oct 20, 2013
    If it is on a 30A breaker then why don't you think it is a 10-20? You could also check the wire gauge out of the box or by opening the receptacle.

    Some references:
    http://www.powerstream.com/NEMA-plug-reference.htm
    http://www.nooutage.com/nema_configurations.htm
    https://www.google.com/search?q=30+*+80%
    VVaci3k.png
     
  4. RDoc

    RDoc S85D

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  5. RDoc

    RDoc S85D

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    It's a10-50. The difference between the two is size, the 10-20 is much smaller, about 1 1/2 inch diameter. Apparently using a10-50 plug on a 30 amp breaker was legal and common for dryers.
     
  6. scottf200

    scottf200 Active Member

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    I would check the wire gauge to determine what amperage you should draw. They may have put in just large enough wire to run the dryer on that 30 amp circuit.
    Wire-Gauge-Chart.jpg
     
  7. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Pay no attention to those amperages listed there. They're close in some regards, but they aren't quite right when you're looking at the larger numbers (it makes the assumption you're using the 60 deg C column, almost everything nowadays is 75 deg C rated, except Romex/NM-B cable).
     
  8. qwk

    qwk Model S P2681

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    Wow. These must be super rare. I have never heard of one. It looks like it's an older version of the 5-20/6-20 outlet.
     
  9. RDoc

    RDoc S85D

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    #9 RDoc, Oct 21, 2013
    Last edited: Oct 21, 2013
    Even at 24A, an overnight charge will produce a full battery to get home.

    I'm thinking about getting the 10-30 adapter and building a 10-50 male to 10-30 female connector to plug into. I believe that will take care of the ground/neutral issue and limit the current to 24A which I don't want to exceed.

    Now all I need is my X!
     
  10. Cosmacelf

    Cosmacelf Active Member

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    Can you take a picture of the outlet and post it? But yes, making a 10-50 to 10-30 adapter and the using Tesla's 10-30 adapter would make sense.
     

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