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Extending/Converting exisiting Nema 10-30R to Nema 14-50R

Discussion in 'North America' started by Hometheatremaven, Dec 27, 2012.

  1. Hometheatremaven

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    My house was built in 1969 and has the dreaded Zinsco circuit breaker panel. As an aside, I think the house also has aluminum wiring. Anyway, as a result of the Zinsco panel, Solar City wouldn't install a Nema 14-50 outlet without replacing the panel.

    Probably not a bad idea to replace it, but since I have an unused Nema 10-30R (receptacle) dryer outlet in the garage, I'd like to adapt it to charge my to-be-delivered-this-Spring Red Tesla S.
    The existing outlet is 250v 30A, controlled by 2 ganged 30A breakers. I used my multimeter and the outlet tests fine.

    I called Tesla, thinking I'd just get the Nema 10-30 adapter instead of the 14-50, but was told the 14-50 comes standard and I'd have to buy the 10-30 adapter for $100. Rather than going that route, I'd like to convert the 10-30R to 14-50R by creating an extension/conversion cord. The extra ground wire from the 14-50R would run to a copper cold water pipe.

    My idea is to extend my power by buying a 10-30P (plug) and wiring it to a 14-50R. My wife doesn't want it on the garage floor, so I plan to run it over the ceiling of the garage and down the wooden center post.

    So my questions are:

    1. Does the Tesla S automatically sense the incoming voltage and amperage and adjust it's charging accordingly? I know the 10-30R only supplies 250V @ 30A, but I think that will be plenty for the small trips I normally take. But will the 14-50 adapter cause the Tesla to "look for" 40A?

    2. The existing 10-30R is about 34 feet from where I need the power. What gauge wire should I use to extend the 250v 30A receptacle 34 feet? Can I use 10/3 with ground (Home Depot said this should work) or should I use 8/3 with ground?

    P.S. I know this isn't to code and would take it down when I sell the house.
     
  2. FlasherZ

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

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    #2 FlasherZ, Dec 27, 2012
    Last edited: Dec 27, 2012
    Under no circumstances would I ever, ever, EVER do that with a Zinsco panel. No, NO, NO!!!

    If you forget to turn the car down from 40A and it attempts to draw it, and your Zinsco breaker fails (roughly an 80% chance), you will melt the wiring and burn down the house.

    To your questions:

    It will cause the car to draw 40A. It can't tell what kind of wiring you have or what type of breaker. If your breaker trips, you'll be safe; if not, you'll be creating a giant space heater in your walls with the wiring!!!

    For a 24A (NEMA 10-30R) application, 10/3 is what you should use. But as I mentioned earlier, DO NOT DO WHAT YOU WANT TO DO! You *will* burn your house down!!!

    Please, please, PLEASE do not do what you want to do. You're buying an expensive car, don't burn down your house. Zinsco panel replacement will cost you $1500-2000. Your deductible is likely to be about half that, or more. It's not worth risking your life and every one of your possessions.

    - - - Updated - - -

    I'm sorry, I have to post this again. Please do not do this. Just buy the NEMA 10-30 adapter for $100. It's only $100. There's a very, very strong reason that Solar City refused to do that install. I have seen houses burn this way.

    (This type of stuff is what really concerns me about the equivalent of putting a gas pump at everyone's home...)
     
  3. brianman

    brianman Burrito Founder

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    Flasher, do you have a guess on the impact replacing the panel might have on resale value? That might help tip the scales in the financial calculation.
     
  4. FlasherZ

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

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    #4 FlasherZ, Dec 27, 2012
    Last edited: Dec 27, 2012
    Considering that most insurance companies will no longer insure a home with a Federal-Pacific Electric or a Zinsco panel (if they know of it), it's likely going to be something that will be a condition of sale. An inspector WILL point it out and recommend replacement before you buy the home. As to whether you must replace it, or the buyer chooses to do so, will depend upon buyer or seller's market.

    The aluminum wiring isn't so much of an issue. The proper use of NoAlOx and AL-rated devices helps, and you should always use an electrician to install them (because AL becomes brittle with age).

    Finally, the OP should also be aware that if the house does burn, and it's found that you used the adapter cord to plug a 50A device into a 30A outlet, most insurance companies can refuse to pay the claim, because a non-listed device that violates provisions of the NEC was used.

    With a Zinsco panel, you should assume you don't have any protection for overcurrent at all. It is going to be too easy to forget to set the charging amps down, and draw too much current.

    For example, consider if you plug in the car in the late afternoon. A new update comes to the software, you click "install at 2 am". The software installs at 2 am while you're sleeping, and for some reason the preferences are wiped out (because it's a new major version). The car boots the new software, then attempts to charge post-update at 40A (because it lost the 24A preference), right around 3:30 am, and your breaker refuses to trip. The wiring in the wall heats up... you project the rest.
     
  5. dsm363

    dsm363 Roadster + Sig Model S

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    I don't know the details like FlasherZ does but agree that it's not worth messing around with things like this. If you're going to spend $60,000+ on a car then $100 for an adapter to be safe is worth it. Sounds like you should probably get the panel upgraded anyway if you are planning on staying in the house a few years.
     
  6. brianman

    brianman Burrito Founder

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    Thanks, Flasher. If I was in the OP's situation, it would be a no brainer. If there's a decsion to be made for financial reasons, it would be about what option to remove from the Model S to cover the house upgrade cost.
     
  7. mknox

    mknox Well-Known Member

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    As a 34 year electric utility veteran, I agree 100% with FlasherZ's assessment.

    One note of caution with Al wiring: it is susceptible to nicks when stripping the insulation which can lead to breaks and overheating. (Cu is a softer metal and less prone to this). Anyone doing their own work with Al wiring should be very careful when stripping the insulation, and always use properly rated devices.

    I think they've backed off on this a bit, but at one point insurance companies were balking at aluminum wiring too.
     
  8. strider

    strider Active Member

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    Why not just get the 10-30 adapter from Tesla? I'm sure if you talked to your DS they would give you a 10-30 instead of the 14-50 for free. Heck on the TM/com site it said that Model S comes w/ a 120V adapter and a 240V adapter of your choice. So by the time you get your car they'll have the 10-30 through UL and just get that with your car. Am I missing something?
     
  9. Hometheatremaven

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    FlasherZ:

    Thank you so much for your impassioned answer. I got the idea for my extension/conversion from here: http://www.teslamotorsclub.com/showthread.php/10570-Nema-10-30
    It seems that I remember after reading this link, that I could do what I proposed. Do you disagree with this link?

    I respect your expertise and don't want to do anything stupid. In order to talk to an electrician intelligently, I need to know:

    1. Can I program the Tesla S to only draw 30A 250V (the capacity of my Nema 10-30R) if I'm using the Nema 14-50 adapter? The advantage of using the 14-50 adapter is the flexibilty of using it at RV parks etc. Also, what if the 10-30 adapter isn't available by the time I get my Tesla?

    2. Will the Tesla automatically try to draw 40A with the 14-50 adapter, or will it simply draw what it's given? Your previous answer seems to indicate it will try to draw 40A, but I want to confirm this and see if this can be overridden (per #1 above).

    3. If I just extend the 30A 250V 10-30 receptacle 35 feet and terminate it with another 10-30R (assuming I can get the 10-30 adapter), should I use 10/3 or 8/3 wire? Obviously I don't need ground if I do this.

    4. Why did you say that the Nema 10-30R is 24A? I believe it's rated at 30A. I have 2 30A ganged breakers on the old dryer line which I planned on using for the Tesla.

    5. Assuming the Zinsco box is still functioning properly (which it believe it is) is there any reason using the Tesla 10-30 adapter wouldn't charge my Tesla properly at 30A?

    Thanks everyone for helping me make an informed decision.
     
  10. Doug_G

    Doug_G Lead Moderator

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    They must have because the stuff is still being installed. My 2001-vintage house has copper wiring, but when I had the service upgraded to 200A I noticed the original meter-to-panel connection was aluminum. It was switched to copper during the upgrade, though.
     
  11. FlasherZ

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

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    It's different for service-entrance cables versus in-wall circuit wiring. Service entrance cables are almost always AL because they're short runs inside the home, multi-strand, rarely touched once installed, and they are very, very expensive for CU. It's the in-wall wiring, which gets moved around, modified, etc. that AL is no longer used. There was a brief period in the mid-60's to mid-70's where AL wiring was used in homes.
     
  12. Zextraterrestrial

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    You could put a sub panel w/ a 30A double breaker for about $50 before the 10-30 outlet
     
  13. FlasherZ

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

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    Yes and no. It would make it safer, but touching the existing circuit invalidates the use of a NEMA 10 receptacle and he'd have to replace it with a 6-30 or 14-30.

    It's just really inappropriate to keep such a dangerous installation. It really is a serious fire hazard. Why would you even think to keep such a nightmare there?
     
  14. mknox

    mknox Well-Known Member

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    Insurance companies have weird rules. A friend of mine bought an old century-home with a 60 amp main service and knob-and-tube wiring. They wouldn't insure her with a 60 amp main, but made no mention of the knob-and-tube wiring (the bad part). 60 amps was plenty for her load (all gas appliances) but she dutifully replaced it with a 100 amp main and got her coverage. The knob-and-tube remained! She has since sold the house.

    There is nothing inherently dangerous about Al wiring (electric utilities use it all the time on both overhead and underground distribution lines) as long as it's handled and installed correctly.
     
  15. TXjak

    TXjak Owner/Investor/Advocate

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    If it is the breaker, there are other brands that can be used (search Amazon for Zinsco breaker). If not, what is it about the panel that makes it inevitable that the breaker will fail?
     
  16. Hometheatremaven

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    FlasherZ:

    Thank you so much for your impassioned answer. I got the idea for my extension/conversion from here: http://www.teslamotorsclub.com/showt...570-Nema-10-30
    It seems that I remember after reading this link, that I could do what I proposed. Do you disagree with this link?

    I respect your expertise and don't want to do anything stupid. In order to talk to an electrician intelligently, I need to know:

    1. Can I program the Tesla S to only draw 30A 250V (the capacity of my Nema 10-30R) if I'm using the Nema 14-50 adapter? The advantage of using the 14-50 adapter is the flexibilty of using it at RV parks etc. Also, what if the 10-30 adapter isn't available by the time I get my Tesla?

    2. Will the Tesla automatically try to draw 40A with the 14-50 adapter, or will it simply draw what it's given? Your previous answer seems to indicate it will try to draw 40A, but I want to confirm this and see if this can be overridden (per #1 above).

    3. If I just extend the 30A 250V 10-30 receptacle 35 feet and terminate it with another 10-30R (assuming I can get the 10-30 adapter), should I use 10/3 or 8/3 wire? Obviously I don't need ground if I do this.

    4. Why did you say that the Nema 10-30R is 24A? I believe it's rated at 30A. I have 2 30A ganged breakers on the old dryer line which I planned on using for the Tesla.

    5. Assuming the Zinsco box is still functioning properly (which it believe it is) is there any reason using the Tesla 10-30 adapter wouldn't charge my Tesla properly at 30A?

    Thanks everyone for helping me make an informed decision.
     
  17. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Yes, you can set the charge level.


    A continuous load is only allowed to be 80% of the rated load to prevent overheating of the wires. That's why it's 24 amps. Same thing for the HPWC, it needs a 100 amp circuit but can only charge at 80.


    That is the problem, Zinsco boxes have been proven not to function properly. There is no such thing as a properly functioning one.


     
  18. FlasherZ

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

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    The buss bars in Zinsco panels tend to burn because the breakers don't maintain good contact. This causes intense heat which can weld breakers closed so they won't trip.
     
  19. FlasherZ

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

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    #19 FlasherZ, Dec 28, 2012
    Last edited: Dec 28, 2012
    I disagree with anything that violates the NEC... except AFCI breaker rules but that's another story...

    The reason I reluctantly tell people how to make these adapters is because people will rig something up anyway and I try to make it as safe as possible for them. But since you told me you have an FPE or Zinsco panel, I cannot in good conscience tell you to do anything else than replace that panel... it's deadly.

    You can, but there is no guarantee it will retain that setting. Consider the case I mentioned where a software update would reset the preference. If that happens at my house, the breaker trips. I'd that happens at your house, the house burns down... at 3:30 am. While you're sleeping.

    It can be overridden to lower values but cannot go above 80 pct of circuit size. By default it will try to charge at 40A (80 pct of circuit). As I mentioned though... if that setting gets lost or accidentally upped, you should consider it as if you have no protection with that Zinsco panel.

    NEC requires ground for any new installation to include your extension. Furthermore you cannot install another 10-30R where there is not one today. Your insurance company will refuse to pay a claim if it is discovered your home burns with this modification, whether or not it caused the fire... trust me, I've seen this happen.

    The Tesla charger qualifies as a continuous load because it typically operated for more than 3 hours. Continuous loads must run at a maximum of 80% capacity except in a few circumstances that cost far too much.

    There is no way to confirm this test short of specialized equipment and even in that case a successful trip can set up a failure to trip the next time. That's why these things are so dangerous.

    The 24A limit is due to continuous load requirements as mentioned above.


    Please don't endanger your life and others who live in your home by trying to rig up something. Really, it's not worth it.
     
  20. herbvdh

    herbvdh Member

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    Please read this here What Is A Zinsco Panel and Why Should I Care? | U.S. Inspect this is scary. I would replace it immediately if not sooner. I have my PhD. in engineering and did enough EE study to know that Zinsco is a NONO! I remember in class that we were told circuit breakers were no good because they weld together etc. now I have a better understanding of what we were taught.
     

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