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Nema 10-30?

Discussion in 'North America' started by dadaleus, Oct 7, 2012.

  1. dadaleus

    dadaleus 4GETOIL P85#S70,FdrX,S85D

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    Hi all,

    Question for those more electrically inclined than me... I'm trying to figure out how I'm going to charge when I visit my parents' house. (I'm also looking into having an electrician install a NEMA 14-50 in their carport, but I'm not certain I can get this worked out.)

    They have a NEMA 10-30 outlet for their dryer, but I'll have to use an extension to get to it from the car. I can't find a NEMA 10-30 extension though. Nor a 6-30 or 6-50 which are also 3 prong (I know I'd have to limit the amperage to 30 with the 6-50).

    Wondering if anyone here who knows more thinks I could charge off of a 4 prong connection if the ground wire is not connected, such as by adapting the NEMA 10-30 to a NEMA 14-50 (for which I can get an extension cord)? If I go with the 14-50 I know I will have to keep the amperage down to 30 or below. This would also have the benefit that the extension cord is higher amperage than needed which should help avoid errors I would think.

    This is for a model S, but since I doubt anyone has tried this with the S, I'd be happy with an answer for the Roadster. If it works for the Roadster, I'm willing to take my chances that it would work for the S.

    Thanks all!
    -Jason
     
  2. doug

    doug Administrator / Head Moderator

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    Hmm.. I'd try harder with the electrician putting a 14-50 in the car port. NEMA 10-30 omits ground. Sometimes you can ground through the neutral, but I don't know if the UMC will like that (not considered good practice). The NEMA 14-50 plug on the UMC has a neutral blade, but as far as I know that's left unconnected. For 208-240 V, the UMC requires two hots and a ground.
     
  3. dadaleus

    dadaleus 4GETOIL P85#S70,FdrX,S85D

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    I'll try, but not convinced it's going to work out. It's at the opposite end of the house from the breaker box (which is not near anywhere I could get the car into). Could be quite a project to get a 14-50 added.

    I'm nervous about the whole ground vs. neutral bit not being an electrical type myself. Tesla does sell NEMA 10-30 and 6-30 3 prong connector for the UMC. So it seems the UMC should accept this one way or another. I suppose I could adapt the 10-30 to 14-50 for the extension, then adapt it back to 10-30 and get an official Tesla 10-30 connector. But if the 14-50 connector would take the output of the extension missing a prong it would be a whole lot easier.
     
  4. drees

    drees Active Member

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    stayonline.com has a bunch of different types of extension cords and can even build custom ones, but there's not a lot you can do when you configure one with a NEMA 6-30 plug.

    Using their custom cord configurator, I was able to configure one with a NEMA 10-30 plug and a NEMA 10-50 connector.

    Not that cheap, though. A 25ft 10awg extension cord will cost $160. Of course, even if you built one yourself, you will spend very close to that amount once you source quality connectors, so it's not that bad.

    Still ideally, I'd see if you can get the dryer plug properly grounded as that gives you a lot more options and also gets you up to code and should be safest.
     
  5. sublimaze1

    sublimaze1 8Dec2012 / Leeroy Jenkins

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    I agree with all the above - plus:

    (1) Extension cords are a bad idea when you are running 30+ amps. Not saying they won't work, but sometimes you can keep a ladder attached to your roof rack with twine too ...

    (2) A NEMA 14/50 in your main breaker is the best choice. A Square D 50 amp breaker with 6 ga wire (you don't need much of a run if you install it on that same wall) is the cheapest solution. It is still $180-$300 depending. Maybe more in your area. But you home will be less likely to be visited by the men in a red truck.

    (3) anytime you can get more amps to your car, it will charge faster. I have a 220/16.9 plug for a welder in my garage, but opted for the 14-50 due to reading all the wonderful posts in the forum.


    Now, I am not an electrician, so something I have said above may ring perilously in the ears of one who is an electrician. I would gladly accept any criticism if something is awry above.

    WJ
     
  6. dadaleus

    dadaleus 4GETOIL P85#S70,FdrX,S85D

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    Drees: Thanks. I'm going to check this out.

    Sublimaze1: The problem is the breaker box is on the far end of the house from the carport and driveway. So they'd have to run something like 150 feet of wire on the outside of the house to get to the carport. And I visit maybe 3 or 4 times a year. I think a kluge solution isn't necessarily such a bad thing under these circumstances.
     
  7. TEG

    TEG TMC Moderator

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    I have a personal adapter I made to charge my old RangerEV at a friend's shop.
    It has NEMA10-30 plug, NEMA14-50 socket, and the ground comes out as a long wire with a beefy aligator clip on the end.
    (My old Ranger AVCON EVSE has a NEMA14-50 plug on it to be somewhat portable.)
    I clip the grounding wire to the metal wiring conduit that is coming from the breaker box (which is very close to the 10-30 outlet) before plugging in anything else.
    I verified, using a VOHM, basically no resistance between the grounding pin on the 14-50 and the grounding rod going into the physical ground behind the breaker box.

    It all works, nothing has fried, popped, or had any problems - but with that said, I can't recommend anyone else do this.
     
  8. doug

    doug Administrator / Head Moderator

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    I was going to say maybe you can just wire your own ground, but I didn't realize that Tesla is offering a NEMA 10-30 adapter.
    http://www.teslamotors.com/models/charging#/outlet

    So that might indicate they have the ground-neutral thing worked out.

    I'd just make my own extension and make sure the wires connect straight through.
     
  9. qwk

    qwk Model S P2681

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    Now I dont know about a model S UMC since I havent used one, But a roadster doesnt need the ground to charge. I'm guessing that the Model S should be the same.
     
  10. FlasherZ

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

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    You really, really need a safety grounding connector of some kind, and I believe that the Tesla chargers will refuse to charge without a ground of some sort (although I can't confirm, I do recall some posts about Roadsters sensing ground faults). You do not want to simply leave the ground conductor unconnected, you need a path to ground to trip your breaker in case of a short of a hot wire to the chassis. Otherwise a human touching the car could create a path to ground and die.

    As Tesla can charge fine on a NEMA 6 series, it doesn't require a neutral, and only draws on the hot pins. In fact, Adelman said on the NEMA 6-20 thread that the neutral was left unconnected.

    I'd recommend 2 approaches, depending on whether you intend to leave the adapter at your parents' home, or whether you want it to be portable.

    1. Semi-permanent use: Do basically what TEG says above... take a length of 10-3 w/ ground. Attach the 2 hot legs and neutral to the correct pins on a NEMA 10-30P plug and NEMA 14-50R receptacle. Attach the bare ground to the 14-50R's ground pin, and attach it properly to a grounding location (either a properly-connected metal electrical box, a cold copper water pipe, metal electrical conduit, or some other source of equipment safety ground). Test this ground by using an ohmmeter between the ground pin on the 14-50R and a known good ground. I would recommend against what TEG did -- alligator clips, even beefy ones, don't always make or keep the best connections -- you can use them, but test the ground EVERY TIME before you use it, as he did. Label the 14-50R with "FOR TESLA CHARGING USE ONLY -- 30A MAXIMUM". Check that the breaker is 30A maximum.

    2. Portable use: If you want to use the NEMA 10-30 receptacle at your parents', you can wire up a cable that has the NEMA 10-30P on one end and NEMA 14-50R on the other end. Tie the NEMA 14-50R's ground and neutral pins together and feed from the neutral on the 10-30P. Mark the 14-50R with "FOR TESLA CHARGING USE ONLY -- UNGROUNDED RECEPTACLE -- 30A MAXIMUM" or something similar. 2 hot conductors must be minimum #10 AWG, ground can be #12 if you're using separate conductors (otherwise just use 10/2 w/ ground). Confirm your parents have a 30A breaker before using, as I've seen NEMA 10-30's on larger breakers before, and you wouldn't want a fire created by accidentally leaving the Model S at a higher amperage that didn't pop the breaker but burned up the wiring.

    Obviously, the use of any device like this is at your own risk, and the proper way to do this is to have a 14-50R properly installed. :)
     
  11. qwk

    qwk Model S P2681

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    I think you are confusing neutral with ground. While both are grounded to the breaker box, neither a 10-50 nor 10-30 have grounds, only neutrals. You could do two things that are not up to code if you have a long wire run and for whatever reason dont run a new seperate ground wire to the 14-50 or 14-30. One is leave the ground unconnected, the other is hook the ground and neutral together(not recommended). If you leave the ground not connected to anything, you just have to remember to not plug in any device that requires both a neutral and a ground, or it may cause problems.
     
  12. dadaleus

    dadaleus 4GETOIL P85#S70,FdrX,S85D

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    Thats for the well thoughtout responses. What would be cool is an adapter that takes the 14-50 hots and neutral to the 10-30, and also has a 5-15 plug just for the ground. But sure, I could semi permanently wire in something for the ground. I just have to be able to unplug it to plug in their dryer.
     
  13. FlasherZ

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

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    Are you referring to me?

    You *never* want to leave the equipment safety ground conductor (the "ground") of a NEMA 14-series receptacle unconnected. It creates a safety hazard if one of the hot wires ever becomes broken and/or shorted to the chassis.

    The only reason that you can tie neutral and ground together when converting from a 10-30P to a 14-50R for model S is because a) NEMA 10 series applications generally expect equipment chassis ground to be done through the neutral conductor, and b) Tesla doesn't require the neutral conductor, and therefore does not use it as a current return conductor. As a result, the neutral wire can act as a safety ground in this case without too much risk. Mark the adaptor properly, ensure it's not used for anything else, and throw it away when the model S goes away. As I said, the proper way to do this is to wire a 14-50R properly, but if all you have is a NEMA 10-30, this will do and is reasonably safe for charging a model S. (I believe if you purchased a NEMA 10-30 plug for the UMC and looked at the pin-outs, you'd find they effectively do the same - car chassis to the neutral, and hot-hot to the chargers.)

    You do not want to use this cable for any other appliances, especially those that make physical electrical contact with earth ground, as it can create effectively a second neutral-ground bonding point, which is only supposed to happen at one point -- the service panel.
     
  14. dhrivnak

    dhrivnak Active Member

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    I made such a connector and have used it successfully. I needed to charge at my Son's apartment and while i have a NEMA fourteen fifty his dryer is NEMA ten thirty. I tied neutral to ground as they tie back to the same place. A trip to Lowes and less than forty five dollars i was set.
     
  15. qwk

    qwk Model S P2681

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    I think we are saying the same thing, just using different wording. The only difference I can see is on the connecting the ground to neutral which works, but isn't needed as the car just uses the neutral as ground like you mentioned.

    - - - Updated - - -

    To the OP, I think that waiting for the 10-30 adapter from Tesla is the thing to do in your case though. It's very simple, and just plugs in without much risk. All of this rewiring outlets temporarily can not only be time consuming, but you definately need a multimeter, and the necessary tools there when you attempt this.
     
  16. FlasherZ

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

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    Well, we want to be crystal clear here for safety, so I'm happy to clarify. You left me with the impression that you would prefer leaving the ground "unconnected" over tying the neutral and ground together in this statement:

    Leaving the "ground" pin unconnected on a NEMA 14-50R is a very, very bad idea, and I don't want to leave anyone with the impression that you should leave it unconnected. That's all. In preference order, 1) you want to run a separate ground from the NEMA 14-50R's safety ground to a safety ground conductor somewhere, so that it's unconnected to the neutral bus; 2) you connect the safety "ground" terminal on the NEMA 14-50R to the "neutral" return terminal on the NEMA 14-50R, then connect that to the NEMA 10-30P's "neutral" pin; 3) you connect the safety "ground" terminal on the NEMA 14-50R to the NEMA 10-30P's "neutral" pin and leave the 14-50R's "neutral" terminal unconnected, making sure there is PERMANENT-QUALITY MARKING that neutral is not present. There isn't a 4th option to leave the ground unconnected, it's a giant safety hazard. For #3, (the suggestion that you not connect the neutral pin on the NEMA 14-50R), see the NEMA 6-20 thread. If your cord is properly marked, it's not so much a big deal but you never want to do this on a permanently installed receptacle (it would unlikely pass inspection).

    In *most* cases, the NEMA 10-30R you plug into will be served from a run to the service panel, where neutral and ground are bonded together, and as a result in combination with the fact that the UMC doesn't require neutral, there will be no functional difference between a 10-30R and a 6-30R there.
     
  17. qwk

    qwk Model S P2681

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    Can you do me a favor and just do a continuity test on a roadster UMC between the neutral and ground pin of a 14-50 adapter, and tell me how a ground that is not connected to anything helps in terms of safety?
     
  18. ahimberg

    ahimberg Member

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  19. FlasherZ

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

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    The continuity tester on the UMC will simply tell you that the two (neutral and ground) are not connected, and it's because the UMC doesn't need the neutral, and so it's left unconnected. That does not mean the ground pin is not needed. It's connected to the car's chassis, which is what's required for safety reasons. If you do a continuity test between the car's chassis and the ground pin on the UMC's plug when the UMC is attached, I believe you will find they are connected.

    Without that ground being present, if there is a failure of one of the hot legs and it shorts to the car's chassis, a human touching the car while standing on the earth will produce a path to ground and will get one hell of a shock. With it present, it provides enough of a path to trip the circuit breaker immediately. I believe I recall the UMC having GFCI circuitry to provide another safety here, so you have that as well.

    As a rule, equipment safety ground should ALWAYS be present, no if's, and's, or but's about it -- that's why NEMA 10 receptacles are no longer permitted for new installations post 1996 NEC.

    - - - Updated - - -

    The 30-amp connector there is a NEMA TT-30P, and is 120V. The NEMA 10-30P has an L-shaped neutral pin. I did a very quick search last night to find an RV cable to go from a NEMA 10-30P to a NEMA 14-50R for this post last night, but didn't find any in my quick search. It's likely because of the implications of its use and providing a ground.
     
  20. qwk

    qwk Model S P2681

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    Ok, so I dont even know what you are arguing about here. Of course you need a ground to charge(whether you call it neutral or ground), but having both the neutral and ground grounded is not necessary, and can be detrimental to other devices that are plugged in to the outlet. In fact, connecting them together on a outlet receptacle is more risky than just having one not connected. In the case of the roadster, having both connected is in fact the same as having only one connected as it only uses one to charge(as verified by the continuity test). Connecting both would accomplish exactly nothing.
     

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