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Which AWG Wire? Someday want to upgrade 14-50 NEMA (50A breaker) to wall charger (90A breaker)

Discussion in 'Model X: Battery & Charging' started by ctn531, Jul 19, 2018.

  1. ctn531

    ctn531 Member

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    I'm 4-6 weeks out from getting my MX (100D). For now I plan to wire a 14-50 receptacle (50 Amp breaker) because it is cheap (relative) and easy. At some point down the road I'm hoping to score a referral and get a free wall charger (or maybe find one on Craigslist or ebay - anybody out there ???).

    Anyway, I want to size the wire so that when I do install the wall charger, the AWG will be sufficient to support the 90A breaker (72A charging). I'm guessing folks out there have done this. What gauge copper wire is required. FYI - the run from the panel to the wall charger is approximately 60 feet.

    I'm fairly certain 2 AWG copper will work. How about 3 AWG copper?

    Thanks-
     
  2. P85_DA

    P85_DA Supporting Member

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    #2 wont fit the 14-50 plug ..,for that run just put the #2 now and get HPWC

    Also #3 won’t fit the 14-50 ..best u can get by for 14-50 is #6 ...but than than won’t be able to support 72a down the line ..
     
  3. ctn531

    ctn531 Member

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    Sorry - left that part out. My plan was to install a junction box adjacent to the 14-50. This way I can downsize the wire going to the 14-50. Once the HPWC goes in, the 14-50 outlet and also the junction box goes away and everything will be hard-wired within the HPWC. The HPWC does not use the neutral wire, so I suspect I will cap that wire within the HPWC.
     
  4. P85_DA

    P85_DA Supporting Member

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    .ok so what does ur run look like to j box ?
     
  5. SSedan

    SSedan Member

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    I believe it prudent to have a redundant charging solution, that means $300 for a second UMC capable of just 32amps or a $500 HPWC capable of all 72amps your MX could take.
    The cost to run does not have to be that different. I priced out the wire yesterday and 3gauge copper is $1.02 a foot, HPWC uses 2 that size and a smaller ground. 14-50 often uses 6gauge which I priced at $.88 wire but needs THREE wires that size(might be able to do 8gauge) and the ground which can be smaller plus purchasing an outlet, the $7 one may not take a lot of plugging unplugging well a middle of the road outdoor RV enclosure would be $30-50, and the heavy duty outlet that will handle plugging and unplugging often is like $70 and again you.

    I priced 50 vs. 100amp breakers and the price was $30-40 different. You will likely have to upsize conduit a little too. That said with the 2 large cables vs. 3. Just off the cuff wash the three 6-8gauge cable vs. 2 3gauge ones. Wash outlet cost vs.the conduit upsize, which you are doing anyway.

    If you are going to just risk owning a single UMC then yeah the $500 pricetag of the HPWC is all new cost but if you are going to buy a second UMC then the HPWC is only $200 more.

    There is also the fact that even on the same wire as a 14-50 would have used the HPWC will give you 40amps instead of 32.

    More I look at it the more I fail to see a real case for a 14-50, I suppose if you live close enough to something you feel OK using for all your charging for a few weeks should your UMC die you can call that your backup plan.
     
  6. P85_DA

    P85_DA Supporting Member

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    Looks like OP is running to a sub panel the cost is in the conduit and labor to run 60ft ...with a sub panel assuming he has capacity at main he can have both 14-50and HPWC ...there are some pics where folks use a disconnect so only one can be active either the HPWC or 14-50 depending on his load
     
  7. aesculus

    aesculus Still Trying to Figure This All Out

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    That's what I did. I have a small sub panel with breakers for both the HPWC and the 14-50. If the HPWC fails I can switch the two breakers and use the 14-50. 20160430_141251.jpg
     
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  8. Rocky_H

    Rocky_H Active Member

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    I see that you live in Greenville, Wisconsin, which is pretty sparse and adventurous for having charging available, so I do get that you have a pretty valid concern there. But in most bigger cities, the local Supercharger would be the redundant charging solution if needed for a couple weeks, so I find this suggestion of always needing a backup high power charging method to be odd coming from a lot of other people.
     
  9. patrick40363

    patrick40363 Member

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    When I had my plug installed I had the electrician use the largest wire he could fit in the conduit and plug. It was #4 wire.
     
  10. SSedan

    SSedan Member

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    Actually since I bought the car last August, they put in superchargers in Green Bay 40minutes away, and Oshkosh 30minutes away and Bubolz Nature center 10 minutes away has destination chargers on solar, the Bergstrom dealers all have J1772, and the Menasha Festival foods has some really crappy Charge point. But I also have a 4yo car with 75k and can only pressum the UMC is original. The Superchargers we're late last year the close destination chargers were this year.
    With no service center in the state a new UMC would be a week away.
    In the cold weather we have here I found the 30amp circuit I was using insufficient for consistently timing charging since it is less power than the heaters use, and I have some indication my UMC plug is worn.
     
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  11. davewill

    davewill Member

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    You can always use a pigtail to wire outlet. You can also use a cutoff switch, small panel or load center, as noted by others, to create a local cutoff and make the conversion to the smaller wire.
     
  12. P85_DA

    P85_DA Supporting Member

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    I have seen folks do the pigtail thing to HPWC but I thought

    -not UL certified this way ?
    -it looks horrible pigtail to HPWC :(:eek:
     
  13. ctn531

    ctn531 Member

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    I'm definitely not going to pigtail to HPWC. Once the HPWC goes in, the junction box & the 14-50 outlet are both coming out. The feeder wire will be terminated directly to the HPWC.

    The sole purpose of the junction box is so that I can down-size the wires going to the interim 14-50 outlet ...
     
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  14. davewill

    davewill Member

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    Why would it look horrible? It would be inside the receptacle box. And you'd remove the pigtail and run the big cable all the way in when wiring the wall connector.

    But a small load center or panel is the way to go, I think. Gives you an easy way to wire a second wall connector on the future or even keep the 14-50 around as a backup.
     
  15. tga

    tga Supporting Member

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    If you're planning to charge at >60A, NEC requires a local disconnect (some inspectors will allow a subpanel within site of the HPWC to count), so you could use that as your junction point. Run the heavy gauge wire to the disconnect, then smaller gauge from the disconnect to the outlet. This assumes the two sets of terminals' allowable wire size ranges overlap.

    Personally, for planned 72A charging, I'd get a 100A switch with a Cu/Al rating on eBay (used ones are a cheap and plentiful), run 2Ga Al SER from the panel to the switch, and a short run of 2 or 3Ga Cu to the HPWC. No point in paying for copper for that long run.
     
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