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Extension cord for both NEMA 5-15 and 5-20

Discussion in 'Model S: Battery & Charging' started by TexasEV, Jan 5, 2014.

  1. TexasEV

    TexasEV Active Member

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    I've read through the extension cord threads (thank you FlasherZ and others) and I haven't seen this addressed:
    Is it possible to carry one extension cord for infrequent 120V charging that could be used for drawing 16A when plugged into a 20 amp circuit and 12A when plugged into a 15 amp circuit? My thought is to have a 10 AWG cord made with 5-20R on one end and 5-15P on the other. It could be plugged into to either a 5-15 or 5-20 wall outlet. With the standard 5-15 UMC adapter it would draw the usual 12A when plugged into a 15 amp circuit. With the 5-20 UMC adapter it would draw 16 amp when plugged into a 20 amp circuit. Or does the 5-20 wall outlet only allow 15 amp if a 5-15P is plugged into it? Does the outlet act differently if it has a 5-15P or a 5-20P plugged in?
     
  2. cinergi

    cinergi Active Member

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    I use this cable: Coleman Cable 026198802 20-Amp Generator Cord 5-20P to 5-20R, Lighted, 100-Feet - Amazon.com

    and I made an adapter so I can plug that cable into a 5-15 receptacle and charge at 12 amps. The danger there is you could accidentally charge at 16 (which should pop the breaker, but it's still dangerous) if you forget to swap out the adapter on the UMC to the 5-15.

    The outlet won't work differently, but I don't know that a 5-15 plug could carry 16 amps continuous load (act as a 20 amp plug) -- which is why I made the adapter.

    Hope that helps!
     
  3. Cosmacelf

    Cosmacelf Active Member

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    It'll work fine. The 5-20 receptacle doesn't know what kind of plug is connected to it, so either a 5-15 or 5-20 plug will work. And I wouldn't be worried about drawing 16 amps from a 5-15 plug, it will work fine. The tolerances aren't that tight!
     
  4. FlasherZ

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

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    There are some older outlets I would never try to draw even 12 amps from... :)
     
  5. deonb

    deonb Active Member

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    No. Only as dangerous as plugging in 2x 8A devices at 2 random outlets at your house and finding out later that they happen to be on the same circuit, causing a trip.

    If accidentally overdrawing current was specifically dangerous, outlets would be individually wired to prevent it. They're not.
     
  6. TexasEV

    TexasEV Active Member

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    That aside, FlasherZ, do you agree this one custom cord could be used for both 15A and 20A outlets and get the same amps safely from each that separate extension cords would?
     
  7. linkster

    linkster Member

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    #7 linkster, Jan 5, 2014
    Last edited: Jan 5, 2014
    Yes, you can use one extension cord for both 5-15 and 5-20 receptacles.
    No, the outlet does not act differently.

    You are correct not to "pull" 16amps from a NEMA 5-15 receptacle.

    I prefer not to use custom cords, so i use a molded end 12AWG 5-20P to 5-20F extension cord and a Conntek p/n 30129 5-15P to 5-15/20F adapter between the outlet and the extension cord if only a 5-15 receptacle is available and of course along with the matching/appropriate 5-15 UMC adapter.

    Just curious as to why you want to use a heavy 10AWG (load carrying capacity of 30amps) extension cord?
     
  8. cinergi

    cinergi Active Member

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    I've melted the plugs and receptacles on two different 12 gauge cords at 12 amps. I wouldn't recommend 16 amps on a 12 gauge.
     
  9. TexasEV

    TexasEV Active Member

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    The breaker might be a long way from the outlet in a public garage, and with the new firmware being more sensitive to voltage drops I thought it best to be more conservative and carry 10 with me rather than 12. The 20 amp extension cord cinergi mentioned above is 10 AWG also.
     
  10. cinergi

    cinergi Active Member

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    A 15 amp plug can only handle 12 amps continuous. That's why I'm hesitant to recommend that a 15 amp plug could handle 16 amps continuous. While the contacts physically look the same, there may be differences at the connection from the spades to the wires. Why risk a fire when there's a simple solution?

    - - - Updated - - -

    I mean dangerous in terms of the quality of the installation. When you're plugging into lord knows what kind of plugs in the field, it's a little riskier to draw power on the edge of the limit as you may not pop the breaker or pop it fast enough. I've personally created some relatively major overloads by accident and couldn't believe how long it took for the breaker to pop.
     
  11. linkster

    linkster Member

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    Sounds good. Also keep in mind of possibly other "items" that may by drawing current as well as your "S" on an unknown branch circuit. You can purchase a good quality Yellow Jacket 10ga. 100' for approx $160 on amazon. However, I recommend a few shorter cords that can be connected instead of one 100' in case you only need 25 or 50'.
     
  12. cinergi

    cinergi Active Member

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    Personally I shied away from 2 50' cords because each additional junction is additional loss and heat and failure point. That's one of the lessons I learned when I had a 12 gauge 50 and 12 gauge 25 connected together. The 10 gauge 100' cord may be way too long in certain cases, but it can always handle the load.
     
  13. linkster

    linkster Member

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    #13 linkster, Jan 6, 2014
    Last edited: Jan 6, 2014
    Tex,
    Too bad your not on the east coast 'cause I would sell you my 22 lb. unused 10ga 5-20P to 5-20F 100' for $125 that I purchased one year ago when the "S" arrived along with an unused 8ga (32A continuous) 6-50P to 6-50F 25’ for $75. My current (pun intended) two "workhorses" are my previously mentioned 12ga 5-20P to 5-20F that wifey also uses for 220v charging @12 mph charge rate at 10-30 ('95 earlier construction) or 14-30 ('96 later construction) dryer receptacles where she doesn't need to adjust the appropriate amp draw since the S automatically adjusts this correctly on this particular "plug and play" arrangement and my 24A L6-30 "system" that also requires no manual input by operator when used on 30-50 amp circuits. No wasteful, extraneous 220v neutrals here in this camp!

    Good Luck!
     
  14. SamGarber

    SamGarber S85 "Whale Shark"

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    By the way - had a need for a 6-20 adapter because my local train station garages seems to have this one. Tesla does not produce that tip for the UMC today.

    Chose http://discountpv.com/ to get a custom adapter cable. Got it in a couple of weeks and now used it twice! Worked like a charm, and was able to get upwards of 15mi/hr out of the outlet.
     
  15. wycolo

    wycolo Active Member

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    100 ft 10 ga extension @harbor freight for $100-. Very good quality and very heavy!

    Why pay $60- extra at Amazon then have to ship all that weight, if you can get to a H.F. Store?
    --
     
  16. neroden

    neroden Happy Model S Owner

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    Breakers are not as reliable about breaking as fuses were. Oh well, such is progress -- breakers are used rather than fuses because of idiot-proofing, not because they were technically superior.
     
  17. FlasherZ

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

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    The NEC tables for SOOW and SJOW cords call for 10 ga. up to 25 amps (2 current-carrying conductors), and 12 ga. for 18 amps. Then you need to add the 1.25 factor for continuous loads. So you really need 10 ga. if you plan to draw 16 amps. Yes, a single cord could handle both of them provided you use 20A plug and outlet.
     
  18. linkster

    linkster Member

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    #18 linkster, Jan 11, 2014
    Last edited: Jan 11, 2014
    Flash,

    a. does the ampacity rating differ if I use SJT vs. SOOW and SJOW cord?
    b. at what total (from load center) length for 12 and 10AWG SJT cords is the ampacity decreased?
    c. should one adhere to the NEC over the UL guidelines, if so, why?

    thanks
     
  19. FlasherZ

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

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    1. No difference between J and O.
    2. UL guidance is 50', NEC makes no determination for distance in 400.5(A).
    3. UL guidelines roughly mirror NEC but account for longer cables over 50'.
     

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