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NEMA 14-50 Question

Discussion in 'Model S: Battery & Charging' started by arlorose, Aug 18, 2017.

  1. arlorose

    arlorose Member

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    Hi, all!

    I feel like this is an "if you don't know, a professional should do it" kind of question... but here goes.

    I have a Bosh J1772 charger in my garage I had installed for my previous electric car. I have had zero issues with it and the adapter over the last few months of charging my Model S. But... I sure would like the auto hatch open, and the sleeker handle would give my significant other an extra inch or two room pulling into the garage.

    Here's my question. Can I wire a 14-50 wall outlet between the dedicated garage fuse box and the existing charger without issue? I could also unhook the current charger and have the wires end at the 14-50. Ultimately I'll get a Tesla wall charger, but it seems silly to do that if it's $12 for the outlet and a tiny amount of elbow grease to use the supplied plug-in charger.

    Thoughts?
     
  2. CLLACAB

    CLLACAB Member

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    Not quite sure, but I have the same setup. My other car is a Volt. I can say that the Bosch charger runs off of a 40 amp circuit and the Nema runs off a 50 amp circuit.
     
  3. TexasEV

    TexasEV Well-Known Member

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    (Sound of chalk grating on chalkboard)
    Saying something is a "Nema" is like saying something weighs pounds without specifying how many. It's a "NEMA 14-50" outlet he's talking about. All outlets are NEMA something. Dryer outlets which are 30A are NEMA 14-30 or 10-30, for example.
     
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  4. cybergates

    cybergates Member

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    well, for starters, see what Amp circuit breaker is there in the garage fusebox panel for the old EV charger - it's going to need to be a 50 amp fuse to be a NEMA 14-50 (max yield 40A and the "bare wires" 6ga recommended). Otherwise if it's 30 amps you can have a NEMA 14-30 like mine (old dryer outlet socket wired with 10ga romex) and charge using a Tesla 14-30 adapter from their site (which yields 24A). Even a 14-30 does remarkably well and gets me 17-18mi/hr of range...not too shabby overnight
     
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  5. Quick2Judge

    Quick2Judge Member

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    Another non pro answer for you but....#1 want to confirm you will end it at the new outlet, correct? If so I don't see a problem. Check the circuit breaker for the number( (30/40/50) When you turn the breaker off and replace the outlet and plug in your car the first time it will be identified in the car. Make sure the car is manually set for less amps than whatever is on the breaker. I have a NEMA 14-50 / 50 Amps and my car is set for 40 amps from it. That = 30 miles / hour which is plenty for me. Hopefully works for you. Good luck!
     
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  6. gregd

    gregd Active Member

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    How fast (what current) are you charging your car now? If it's 40 amps, then you should have (but be sure to check) a 50 amp breaker and 6 gauge wires. And, assuming there are all 4 wires present (two hots, neutral, and ground), then yes, the 14-50 can be installed, and a 14-50 pigtail connected to the Bosch EVSE to plug into it (something like NEMA 50A Input Cable). Likely as not, the Bosch doesn't use the neutral wire, so you can leave that unconnected on the pigtail (cap with a wire nut). If the neutral wire isn't present in the wall (because the Bosch didn't need it), it would be a code violation to wire up a 14-50 without it, even though the Tesla EVSEs don't use it either. You have to assume that someone in the future might plug something else into the 14-50 outlet that needs it, which would be a problem.
     
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  7. arlorose

    arlorose Member

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    These are exactly the little nuggets I was after. :)

    I know it's a 40 amp breaker in there now, so what I'll likely do is swap it out with a 50 amp and swap the Bosh out with a 14-50 outlet. Then, I could either leave it as-is or get a Tesla wall mount at some point and do the swap again.

    I'll look at my main panel and see if there are any issues with 50 amp sub-load.

    Thanks all!
     
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  8. Lloyd

    Lloyd Well-Known Member

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    Make sure you have wire sufficient for 50 amps! My guess is that it is smaller for a 40 amp load.
     
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  9. gavine

    gavine Petrol Head turned EV Enthusiast

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    I'm not an electrician and experts feel free to correct me, but do NOT simply swap the breaker without checking the wire thickness. If it's a 40A breaker, there's a good chance the wire is not thick enough to sustain 40A of current (via 50A circuit) without overheating the wire and the 50A breaker will let it through without tripping thus risking fire. If it is 6AWG wire, you're good. 8AWG can be okay if it's a very short run. 10AWG = keep the 40A breaker and use a 14-30 outlet with adapter or upgrade the wire.
     
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  10. wws

    wws Member

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    It is actually legal to put a 50 amp receptacle on a 40 amp circuit. There is an exception in the NEC for it. (See Table 210.21(B)(3). And don't draw more than 32 amps continuous from it.) However the other requirement for a 14-series receptacle is a neutral (white) wire - which might not be there in your case. You may have to use a 6-series instead.
     
  11. arlorose

    arlorose Member

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    Once again, I'm thrilled to have seen these replies. I have 8 gauge wire going from the main panel to the garage's subpanel, and 8 again, going from panel to charger.

    Becuase the neutral wasn't going to be hooked up to the outlet, thus it was already not to code, I left the 40amp breaker in the panel, and replaced the Bosh Lvl2 charger with the 14-50 box. Plugged in my Tesla portable charger and it worked like a charm! I got a little freaked out when I saw the car go to a 40amp draw, so I set it to 32amp and will keep an eye on that for a while. I'd imagine that if it was doing a 40amp draw and there was a draw or heat issue the 40amp breaker in the garage would trip (or the 50amp at the main panel, from heat)... but I'd hate to ever have to test that theory.

    Anyway, I'm pretty pleased with this, and the next step will be to at some point swap it out again with a Tesla wall-mount, which I believe I can hand-set when installing the charger.

    I'm pretty happy about this. The Tesla charger is sleeker than the bulky Level 2 + adapter I've been using for the last few months.
     
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  12. gregd

    gregd Active Member

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    You should probably look at the Bosch EVSE and see if there are some settings that will limit the charge current to 32 amps. It should have some switches internally to do this. The Tesla unit does, and should be set accordingly.

    The reason for this is that the cars have been known to "forget" the 32 amp settings, and revert to the full 40 amps. You will be fortunate if the breaker trips, vs the wire overheating, because a sustained 40 amp load risks eventually causing something fail.

    Also, do realize that your 14-50 outlet, wired without a neutral line, and with only 8 gauge wire, is a hazard. If nothing else, very clearly and permanently label it "for 32 amp EV charging only" or some such. If someone were to plug their RV into it down the road, really bad things could happen. If you sell the house, you may have a legal responsibility to disclose this.

    Finally, you mention that the garage panel is connected to the main panel with #8 also. What else is that garage panel feeding? If significant (e.g. dryer?), you may need to back down on the charging current even further - 24 amps or lower - in order to not cause problems there. That link might be the weakest one. Is there any way to upgrade the wiring?
     
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  13. arlorose

    arlorose Member

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    The Bosh (that's no longer connected) was maxed out at 30.

    I fully intend on this socket being gone, and the Bosh re-hooked up if I were to ever sell the place. It's not in a location where anyone could do anything with it without my explicit interaction, and I already labeled it because I'm anal about that kinda stuff. :)

    Nothing but the Garage door opener and two low voltage CFLs are on the line. That had occurred to me as well.
     
  14. tga

    tga Supporting Member

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    Instead of a 14-50, a 6-50 (no neutral) would work with the 6-50 UMC adapter.

    8 Ga is only OK for THHN, THWN, etc wire-in-conduit (75 deg C). 8 Ga romex on a 50A breaker is an NEC violation. 10 Ga on a 40A or larger breaker would always be an NEC violation, regardless of wire type.
    Ampacity Charts

    The outlet would be code compliant, but you can't plug anything in with a nameplate rating greater than the breaker without violating NEC. The UMC, with a 14-50 adapter, has a nameplate rating of 50A, so, no-go. - how does charger not blow circuit breaker?

    Devil's advocate - what if you got hit by a bus and your estate sells the house?
     
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  15. arlorose

    arlorose Member

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    It's a shame a 6-30 doesn't have the same plug layout. That would be fantastic.


    They'd see my clearly labeled outlet that says "TESLA CHARGING AT 32AMPS ONLY, NO NEUTRAL, 40AMP BREAKER, 8AWG WIRE TO HOUSE". :)
     
  16. arlorose

    arlorose Member

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    You know... maybe a 6-30 is the right thing to do, and grab this too:
    NEMA 14-50R to 6-30P Adapter

    But I'd rather not put any more money into this since it'll be replaced with a Tesla wall adapter in a year.
     
  17. wws

    wws Member

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    If it were me, and it was difficult to bring the circuit up to handling a full 50 amps + neutral to do a proper 14-50, I would install a 6-50 and get the Tesla 6-50 adapter for the UMC. Still needs to be dialed down to 32 amps though.
     
  18. cybergates

    cybergates Member

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    If the subpanel is in the garage already prob an electrician wouldn't charge that much to install a 14-50 w/ proper neutral wiring...u probably don't need to long a run?
     
  19. arlorose

    arlorose Member

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    It would be a pain. It's a detached garage behind the house. Not sure where the underground path is to take it to the house, but I'd bet fishing 6AWG to one end and pulling won't work well. I suppose I could try, but I also don't know how big the conduit is either.
     
  20. DarkMatter

    DarkMatter Member

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    Put in a 14-30 and a 30A breaker, or hardwire a Tesla Wall Connector and set it for the 40A breaker. Otherwise you're just inviting trouble, sign or no sign.
     
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