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Wiring question

Discussion in 'Model 3: Battery & Charging' started by krishb, Aug 29, 2018.

  1. krishb

    krishb New Member

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    I have my main panel in my garage. For the time being I wanted to get a 50 amp breaker installed in the panel and then run #4-3 wire to a junction box in my garage. From there I wanted my electrician to run a #6 wire for a NEMA 14-50 outlet. My plan is to use the 14-50 outlet for the time being and later upgrade the breaker to a higher amp later for a dual Tesla HPWC setup if I get another Tesla.

    I had an electrician come earlier today for a quote. He said it is against the code to use #4 and #6 in the junction box. I see a number of people suggesting to use #4 from the main panel to for later flexibility. I am confused now. So, should I be only using only #4 everywhere. Also, if I have the junction box, can I wire to a second NEMA 14-50 outlet, assuming I use only one a time?
     
  2. jdcollins5

    jdcollins5 Member

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    I would ask the electrician to give you the Code Article he is quoting from.
     
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  3. Ejl80

    Ejl80 Supporting Member

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    My understanding as long as the breaker protecting the circuit is at the lowest ampacity of the wiring involved you are fine? I'm not an electrician though. You also aren't saving very much money dropping to the 6 wire for the second half.
     
  4. Lloyd

    Lloyd Well-Known Member

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    It’s pretty hard to wire a 14-50 with larger than #6
     
  5. Ejl80

    Ejl80 Supporting Member

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    A quality 14-50 will easily accept #4 wire.
     
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  6. Lloyd

    Lloyd Well-Known Member

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    Yes but the bends are difficult. I challenge you to do it in a standard depth box!
     
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  7. Cosmacelf

    Cosmacelf Well-Known Member

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    Yes, you're going to need a bigger box :)
     
  8. jdcollins5

    jdcollins5 Member

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    You can get a 4”X4” junction box and a cover that that fits a standard 14-50 receptacle. This gives you more room fo the larger wire size.
     
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  9. Rocky_H

    Rocky_H Active Member

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    I am wondering if there is some miscommunication somewhere, as far as what you are describing here or what the electrician is talking about, or something. It is very commonly done to do a thicker wire run to a junction box and do a smaller run out of that. I agree with @jdcollins5 to ask specifically what he thinks is wrong with it.
     
  10. eprosenx

    eprosenx Active Member

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    I have not seen anywhere in the code that this is disallowed, but it would not surprise me in the least if it was not allowed.

    The danger I see would be someone coming along later and seeing 4awg and being like "oh, I can change this up to a 70a breaker", etc... I wish I understood the code in depth enough to give an authoritative answer.

    One idea here that is common would be to take that 4awg (or even larger - you could consider aluminum) to an electrical panel in the garage and then do branch circuits off of that for receptacles or wall connectors. That gives you the most flexibility and it may provide for disconnect requirements, etc... (you can do one 14-50 and one wall connector for instance...)

    Anyway, just food for thought!

    If it was NEC code legal to do it, you would need connectors that let you splice 4awg to 6awg. I don't think there are any wire nuts that would support this.
     
  11. jdcollins5

    jdcollins5 Member

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    Splices with this size wire is typically done with split bolts and tape.
     
  12. Ejl80

    Ejl80 Supporting Member

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    Or Polaris connectors.
     
  13. jdcollins5

    jdcollins5 Member

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    What are Polaris connectors?
     
  14. Ejl80

    Ejl80 Supporting Member

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  15. karpetkutter

    karpetkutter Member

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    Use 6 Gauge all the way through. Its better to build in quality infrastructure. You wont regret it and it can handle the load.
     
  16. eprosenx

    eprosenx Active Member

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    You mean use 4 AWG? (Which is larger than 6awg)

    Either is fine for a 14-50 but 4awg will handle more amps if you later change to a wall connector or other hard wired EVSE.
     

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