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NEMA 14-50 plug or wall charger?

Discussion in 'Model 3: Battery & Charging' started by eddieb3, Aug 7, 2018.

  1. thecloud

    thecloud As rhythm raced inside, the ship came alive

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    #41 thecloud, Aug 11, 2018
    Last edited: Aug 11, 2018
    Possibly worth mentioning: the OP lives in San Clemente, so could make use of the local supercharger for those exceptional cases where a rapid charge is needed.

    Edit: I mention it because I live near a supercharger as well, and it provides the peace of mind, even though I've only used it once. Charging overnight at 32A has always been more than sufficient.
     
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  2. SSedan

    SSedan Active Member

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    I had to cut a vacation short because a family member ended up in the hospital near home. Got home with not enough to make the round trip to the hospital, charging on a 30amp circuit while unloading in a rush left me with a projected 5% after the round trip. Given the highway speeds summer temps etc. I decided to divert for a brief supercharging costing me 20minutes. Had I had the HPWC it would have charged enough while unloading the family.

    Just once in a year, bit it was enough to get me to spring for the HPWC right after.
     
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  3. Joelc

    Joelc Member

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    If your panel can support it, why not install both? Best of both worlds and also futureproof for the next EV.

     
  4. tpham07

    tpham07 Active Member

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    So a once a year instance was enough for you to disagree with my post, thats nice.
     
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  5. SSedan

    SSedan Active Member

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    Don't be so petty, that once a year that you "need" faster charging makes the few hundred dollars worth every penny. Hope for the best plan for the worst. Going with a wall connector also sets up for future proofing and circuit sharing.
     
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  6. Rocky_H

    Rocky_H Active Member

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    Yes, some people do live in smaller, more isolated places like Greeneville, Wisconsin without easily accessible Superchargers. That's no reason to generalize that for most people. @SSedan, you do have more of a need for faster home charging, while probably most people don't so much, as @tpham07 is referring to.
     
  7. dipstick1

    dipstick1 Member

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    I had a similar decision, New to EV's Fortunately my detached garage has a 100 amp sub panel and the prior owner had some kind of welding hobby , so lots of 240v outlets in 30 and 50a. I purchased a additional tesla I6TlgdgIQlSbrIbLwUXbmQ.jpg mobile charger , one to leave on the wall and one to use at work or travel. I self rewired a dedicated outlet - with a 14-50R with 6 gauge for the 2 hot and 8 gauge ground and set the car to 30a max ( on a 50 amp breaker) I set my charge to start at 1 am and have a no problems with every other day charging, 60 round trip mile commute.
     
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  8. SSedan

    SSedan Active Member

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    There are Superchargers in Oshkosh which I am pretty sure is under 30minutes and Green Bay which is maybe a little over 30minutes.
    Just because it is Wisconsin doesn't mean boondocks, charging at home is still easiest especially if the car is equipped for quick AC charging.
    I am sure many of us run into circumstances where 20minutes at home while you pack stuff for the kids or let the dog out and adding a few miles helps with range anxiety or avoids taking the ICE.
     
  9. eprosenx

    eprosenx Active Member

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    Question: Why bother setting it to 30a max? The UMC gen 2 already has a limit of 32 amps which is TONS of headroom/margin on a 50a circuit.

    Just curious if 30a is a special number for you for some reason? :)
     
  10. eprosenx

    eprosenx Active Member

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    Oh gosh, I just realized that I assume the "Tesla Only" label is because you have no neutral wire?

    That is super dangerous for anything other than a Tesla.

    I highly recommend replacing it with a 6-50 and then buying the $35 Tesla 6-50 adapter for your UMC.
     
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  11. dipstick1

    dipstick1 Member

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    I did order the 6-50 adapter and will replace the outlet ,
    , but have to use the existing until it comes in ,
    30A was just a even number, the 50A is safe at 80% rating (40A)
     
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  12. Skione65

    Skione65 Member

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    @eprosenx,

    Quick Q....I’m installing a Tesla Wall Charger. I have a 60’ run from my Main Breaker Panel in the basement through the wall to the adjacent 2 car garage. I want to future proof and run #2 AWG in 1” EMT from the garage wall up over both car bays and down the opposite wall to the Wall Charger.
    My question is my electrician wants to run Romex in the basement portion from the main panel to the garage wall and then run the #2 AWG Copper from there in EMT to the Wall Charger. Will this give me max Charge rate done this way or should I have him (my plan) run straight #2 AWG copper the whole way from the 100A double pole breaker in the Main to the Wall Charger?
    Any difference or pros/cons.....I’m concerned about max charge rate from Romex to the #2 Cu. (Looking at future proof for 2 Tesla’s load sharing in the future). What do you recommend.

    Any advice greatly appreciated.

    Ski
     
  13. tga

    tga Supporting Member

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    Romex can only be rated at 60deg C, so #2 romex is only good for 95A. Copper THHN/THWN (same stuff, just not wet/wet rated) is rated to at least 75deg, so good for [email protected], more at 90C. See this ampacity chart: Ampacity Charts

    If you use #2 romex, you're allowed to round up the breaker feeding it to 100A, since 95A is not a standard size breaker. But even though you feeding it through a 100A breaker, you are still restricted to only using 95A because of the wire rating. This means you can't set the HPWC to 80A (100A circuit); you are capped at 72A charge (90A breaker).

    If you really want the full 80A charge rate for 2 cars, you'll need to run wire in EMT the whole route (more labor, more $). Or something with higher capacity than #2 romex (#1 AL SER or #1/0 AL SER if running through insulation would work is running to a disconnect or sub panel in the garage). The electrician is probably pushing #2 romex to keep his labor down (although I don't know why he isn't proposing romex the whole way to make him more profit).
     
  14. eprosenx

    eprosenx Active Member

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    ^=== What he said

    A few comments though:
    1. Technically you could actually do #3 AWG copper in conduit if you can get it (might be slightly cheaper than #2). It is rated to exactly 100a in that use case. It would also be easier to shove under the HPWC terminals than #2.
    2. One option here might be to run SER style aluminum cable from your main panel to a sub-panel in the garage and then run EMT from that sub panel with #3 (or #2 if you prefer) over to the Wall Connector. This then gives you a very easy way to add the second HPWC later off a second circuit in the subpanel (also allows you to shut one down at a time for any maintenance). I should call out that circuits to EVSE's over 60a need a locking disconnect. My reading is that a little metal clip in the breaker panel to let you lock it off should be fine even if the breaker is a little ways away, but some AHJ's seem to insist on a disconnect right near the EVSE (or within sight) type of deal. So doing a subpanel might kill multiple birds with one stone for you. Some people will also add a 14-50 of a subpanel as a backup charging method in case their Wall Connector breaks. I would use the "non coincident loads" clause to argue that this extra plug does not need to be calculated in the load calc, though I have seen one person use an interlock switch in the subpanel to make sure that the 14-50 can't be used at the same time as the Wall Connector (I think this is overkill - just make sure your wire is all sized right and you have proper overcurrent protective devices).
    3. If you are planning a future second Wall Connector then think about where you will "split" the wire in the future if you add a second - if you don't do the subpanel then maybe do a junction box with a little bit of wire coiled/bent so you can later tap the second 100a run.
    4. I should also note that to the comment about needing 1/0 AL SER if in thermal insulation: I think they may have changed that yet again in the 2017 code. I think it may only force you into the 60c rating now for very small conductor gauges. Larger ones I think are still allowed to be rated at 75c (please check me ont his).
     
  15. Skione65

    Skione65 Member

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    @tga and @eprosenx,

    Much appreciated guys! I’ll digest this and run it by my electrician.

    Ski
     
  16. SgtTortuga

    SgtTortuga Member

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    I researched both the options of the NEMA 14-50 and the Wall Connector. My initial thought was to go with the Wall Connector, but ultimately went with the NEMA 14-50. One of the best pieces of advice I read was from a Tesla owner who said you do not need to drive around with the UMC on a regular basis, just take it on trips. I have found this to be true.

    I live in the Phoenix Metro area and there are plenty of chargers around if I needed to use one during my regular driving, but I have never needed to use one. There are free Tesla destination chargers in my office building garage, if I needed to use them, but they can be tough to get a spot in, despite the fact there are 6 of them and a 3 hour time limit. I have not used them since I got the NEMA 14-50 installed in my garage.

    I think you need to consider your daily use. I drive anywhere from 60 to 180 miles per day. I have a special time of use plan for EV owners that is 6.19 cents per KWh from 11pm to 5am. Using a NEMA 14-50 at 32A I have never had the M3 charge past 5am. Usually about 2 to 3 hours of charging is all that is needed at 32A.

    If my battery was particularly run down, I would start the car charging earlier in the evening. My wife has an ICE car if we had an emergency and the M3 was not charged.

    Here is a picture of my setup. The power box is on the opposite side of the wall, so this did not require a very long cable run. The holder fro the UMC was purchased on Etsy from someone with a 3D printer.
    Charger.jpg
     
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  17. DUBM3

    DUBM3 Member

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    Due to the sub panel location and setup, my licensed electrician suggests me to install the 50Amp breaker and NEMA 14-50 outlet then connect the HPWC through the 14-50 plug.
     
  18. Toadmanor

    Toadmanor Member

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    Does any one know about length of wire run. I am interested to determine if there are any limitations to the run length for either the 14-50 or the HPWC. I have perhaps a 110 foot run and am curious if any problems with this.
     
  19. tga

    tga Supporting Member

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    Your licensed electrician is suggesting an installation that is (technically) in violation of the NEC. Code requires the installer to follow the manufacturer's instructions, which state the device must be hardwired. Therefore, plug installs are technically a violation. Yes people do it, but they aren't supposed to.

    That's fine. That's not really a long enough run for significant voltage drop. 100 ft of 6ga copper feeding 40A @ 240V gives a drop of ~3V, ~1.3%. No problem.
     
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  20. DUBM3

    DUBM3 Member

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    Thanks for your reply. That’s why he only installed the NEMA 14-50 plug and let me install the plug to the HPWC myself.
     

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