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switch 14-30 outlet to 14-50?

Discussion in 'Model S: Battery & Charging' started by imafan, Aug 17, 2018.

  1. imafan

    imafan Member

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    Hi all,
    I have a 240 outlet installed few years ago for my garage workshop. It has 2 linked 30amp breakers and (2) 10 awg hot wires connected currently NEMA 14-30 outlet. Is it ok to switch the outlet to 14-50 to charge my Tesla? If not, what are my options? Thanks!
     
  2. Cosmacelf

    Cosmacelf Well-Known Member

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    While you could do that, a better idea is to purchase a NEMA 14-30 Tesla adapter for your Mobile Connector. Tesla sells these adapters for both the Gen 1 and Gen 2 Mobile Connectors.
     
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  3. imafan

    imafan Member

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    Thanks! ordered the 14-30 adapter on Tesla site. Does it limit charging to 24amp automatically or do I need to set it?
     
  4. Brass Guy

    Brass Guy Member

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    The adapter signals the car the maximum current. Getting the correct Tesla adapter is the right answer.

    Do not attach a 50A outlet to 10 gauge wire.
     
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  5. brkaus

    brkaus Active Member

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    Automatic

    With the 14-30 adapter plugged in, 24 should be the highest option you see on the center screen (and can turn down from there).
     
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  6. Snowstorm

    Snowstorm Member

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    I have a 14-50 socket hooked up to a circuit meant for a 14-30. Manually dialed down the amps to 24A and it gets remembered for the location. Double check it each time as I have seen it reset to 32A before. It can be done.
     
  7. imafan

    imafan Member

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    Thanks. Was planning to do that but adapter would work better since it select the right amp and I won't need to buy new socket/plug replacements to fit 14-50 which would cost as much
     
  8. Snowstorm

    Snowstorm Member

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    The 14-50 plug cost very little (from stores like Home Depot), less than cost of the adapter. However, I did that at the time because the adapter was not available to purchase from Tesla.
     
  9. eprosenx

    eprosenx Member

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    FWIW, I think this is a bad idea and may violate electrical code. If you have a UMC Gen 1 then its nameplate rating is 40 amps continuous and you are plugging it into a circuit that is only good for 24 amps continuous. If you have a UMC Gen 2 then its nameplate rating is 32 amps and the same applies. I am pretty certain that the "manually dialing down the amperage in the UI" trick does not count for the NEC purposes of calculating load.

    As you mention, the car sometimes "forgets" what your max charge rate setting is and could try to draw too much. My personal feeling is that your home charging setup should be bulletproof and robust as you are there all the time. When on the road and in a pinch, I have no issue doing some "hackish" things like using weird adapters and reducing charging current (since you are more likely to pay attention to what you are doing), but at home I just feel like it should be done in a bulletproof and braindead way.

    Using the appropriate receptacle and the factory Tesla adapter is really the best way to go!
     
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  10. SSedan

    SSedan Member

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    The good 14-50 outlet that handles frequent plugging/unplugging is $70, yes you can find outlets for $10 at the home improvement stores but they are more likely to wear out if you regularly pack up the UMC.
     
  11. eprosenx

    eprosenx Member

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    FWIW, I still would not plug/unplug a 14-50 every day even with the "good" receptacle. I am a fan of the hardwired Wall Connector myself, though a permanently plugged in UMC is fine as well.

    I also have issues with paying 7x for a better quality receptacle. I get differences in quality, but 7x is outrageously different for something that can only be marginally better. People bag on the $10 Home Depot Leviton receptacle, but I would like some evidence as to why it is so bad? It carries a UL rating and so it should be just fine for 40a of continuous load or 50a of non-continuous load (UL does rigorous testing). I can see it not supporting a lot of insertion cycles (since 14-50 was designed for electric ovens and ranges) but as long as you don't unplug your UMC every day it seems like it should be fine.
     
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  12. Brass Guy

    Brass Guy Member

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    I don't imagine one that cost 7x as much would withstand 7x the cycles. And remember we're not doing it while under load.

    Either way, if you're cycling it often you'd better examine the thing once in a while.

    We're off topic now, but at least we know the OP is all set with the right adapter on the way.
     
  13. JPoldo

    JPoldo Member

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    After switching to the NEMA 14-50, hopefully you kept the 30A breakers because they are sized for your wiring. Replacing breaker with a 40/50A model is a fire hazzard if forgeting to dial-down current to 30A. Interestingly, Tesla only allows 40A charging despite NEMA 14-50 plug can handle 50A. Maybe they want to derate power going through the UMC for safety. At 40A, my UMC cable gets warm. BTW, frequent disconnects of UMC is high discouraged in other forums.
     
  14. ucmndd

    ucmndd Member

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    A "50 amp" plug/circuit is only rated for 80% continuous load by code. Thus the max continuous output allowed from a 50A circuit is 40A. This isn't a Tesla thing.
     
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  15. rhumbliner

    rhumbliner Member

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    Since a circuit breaker's purpose is to protect the wire and structure, not the appliance, I don't see how this would be a violation. But, I admit I can't find a discussion in the code that addresses this case.

    I suppose it would cause some confusion if someone thought they could draw more than 30-amps from this 50-amp receptacle and kept popping the circuit breaker, but it doesn't seem to be a code issue.

    FWIW, I agree with @eprosenx that a WC is the way to go.
     
  16. eprosenx

    eprosenx Member

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    I would need to hunt to find the section, but you have to size the circuit for the intended load. In this case, the load is clearly a 32a UMC if used with the 14-50 adapter. I am pretty certain he manually setting he amperage down does not count in the eyes of the code.

    If you had a 14-30 tesla adapter then it would be totally fine since the UMC would limit itself to 24a.
     
  17. JPoldo

    JPoldo Member

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    Thanks for the education on derating current to 40A.
     

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