TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

NEMA 14-50 plug or wall charger?

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

  1. eprosenx

    eprosenx Active Member

    Joined:
    May 30, 2018
    Messages:
    1,697
    Location:
    Beaverton, OR
    Also, if you do need to install a receptacle but you don't have a neutral wire, a 6-50 receptacle is always an option. It is kind of funny that 14-50's have become so popular for EV charging when really they have a superfluous neutral wire. I am sure the reason for that is all because of Tesla: They include the 14-50 adapter by default. And I am sure the reason for that is because 14-50's are a lot more common in the wild than 6-50's (i.e. every RV park in the US has them basically).
     
  2. brkaus

    brkaus Well-Known Member

    Joined:
    Jul 8, 2014
    Messages:
    5,195
    Location:
    Austin, TX
    I’ve noticed that 6-50 are more likely to be on a 40a breaker. Not sure why, or if this is the case everywhere. But that’s my experience.
     
  3. rdlink

    rdlink Member

    Joined:
    Jul 12, 2018
    Messages:
    499
    Location:
    Colorado
    Or.... maybe talk to the new owner?
     
  4. SSedan

    SSedan Active Member

    Joined:
    Jul 24, 2017
    Messages:
    1,381
    Location:
    Greenville Wisconsin

    Absolutely correct, my mind was just focused on having set it up now with the intent of 14-50 later, and if done right now it would be there but I absolutely should have included that thank you.
     
  5. drawfour

    drawfour Member

    Joined:
    Mar 10, 2018
    Messages:
    778
    Location:
    Seattle, WA
    Wait, what? That can't be up to code to have a plug that indicates it's 50 amp but is on a 40 amp circuit.
     
    • Disagree x 2
  6. brkaus

    brkaus Well-Known Member

    Joined:
    Jul 8, 2014
    Messages:
    5,195
    Location:
    Austin, TX
    Yes, it’s allowed. Reason - they do not make a 40a plug. So if you only need 40a your allowed to use a 50a outlet, 40a wiring, and a 40a breaker.

    Sucks, but true.
     
    • Informative x 1
  7. gfunkdave

    gfunkdave Member

    Joined:
    Aug 10, 2016
    Messages:
    42
    Location:
    Portland, ME
    Similarly, my kitchen range is plugged into a 14-50 but is wired with 8/3 Romex and on a 40A breaker.
     
  8. drawfour

    drawfour Member

    Joined:
    Mar 10, 2018
    Messages:
    778
    Location:
    Seattle, WA
    Wow, that's just stupid. They should either make a 40amp plug and outlet, or require that all 40-amp circuits are hard-wired, instead of using plugs for a higher amperage. Or they should not have a 40 amp breaker. That's just asking for someone to miss something. I'm sure a regular electrician would be fine with that - but a regular homeowner just looking at the plug to figure out what he can do is going to get a real shock.
     
  9. FourOhFour

    FourOhFour HTTP Error

    Joined:
    Jun 30, 2018
    Messages:
    44
    Location:
    Connecticut
    A problem that can be solved for $3.64.
     
    • Like x 1
  10. eprosenx

    eprosenx Active Member

    Joined:
    May 30, 2018
    Messages:
    1,697
    Location:
    Beaverton, OR
    For whatever it is worth, it is totally allowed by code. There are specific rules about receptacle types for ranges, etc... but if you are installing just a single receptacle on a circuit I think the only thing code says is that your receptacle needs to be rated at or above the rating of the circuit. Also, when installing it for a specific use case you need to make sure it is of sufficient ampacity for the intended load.

    The reality is that if you have just a 40a breaker (with appropriate ampacity wire) on a 50a receptacle then if you plug in something that needs a 50a circuit then really all that should happen is you may just get nuisance trips on that breaker. The really important thing is that you don't put a higher ampacity breaker on wire or a receptacle that is not of sufficient ampacity for it. (now with that being said, I am not advocating anyone do this - and also, NEC want's the double safety of both the calculated load being below the circuit capacity AND then the protection of the breaker - it is just not all that dire of a situation)

    I don't recommend doing 6-50 or 14-50 receptacles on 40a circuits if you are installing wire new, but if for some reason you only have 40a rated wire already installed there is nothing wrong with running a UMC Gen 2 on a 40a circuit. Totally permitted and code compliant (and safe).
     
  11. Dukeblue02

    Dukeblue02 New Member

    Joined:
    Sep 9, 2018
    Messages:
    4
    Location:
    McLean, VA
    Question for you guys in regards to installing my wall charger...

    1. Cost. A loca Tesla certified electrician says since my current 200amp Home panel is overloaded he needs to add a sub panel below it in order to install the 60amp wall charger and also move some of my current slots down to the sub panel. He says the new install with the sub panel and running everything from my basement to the garage will cost $2300. Does that sound reasonable?

    2. Location of installation. Should we install the wall charger on the left front wall of the garage or in the middle pillar between the 2 garage doors? I feel like the middle pillar gives us more options of where we can park but the front left side of the wall is where we park most of the time. We have the 24’ cord.

    3. I would like the wall charger to run through my current whole house generator but my electrician says that is not recommended by Tesla. It’s a 22kw Generac generator for a 4500 sq ft house- won’t that be able to handle the wall charger if the power goes out? If the power does go out for an extended amount of time I don’t want to be stuck with a car I can’t charge. He says he doesn’t know why Tesla doesn’t recommend charging through the generator. Can anyone shed any light on this?
     
  12. eprosenx

    eprosenx Active Member

    Joined:
    May 30, 2018
    Messages:
    1,697
    Location:
    Beaverton, OR
    $2300 for a small sub panel plus a single new circuit seems a bit steep, but it all depends on the complexity of the job. Can you post pictures of your existing panel (one where you can see all amperages of all handle ties, some with panel cover off if possible, one of the sticker on the door that is readable, and something that lets us see what all the circuit labels are)? Sometimes we can get creative of how to install "tandem" breakers, etc... to avoid the need for adding a subpanel (though there is a good chance that is the best option).

    Install location wise, I wish my Wall Connector was closer to the port on my car. I always seem to have an armful of stuff when going to use my car and I wish I could do all the charging connecting one handed. As it is, I need to unspool/spool one round of cable in order to plug/unplug which takes two hands. Sometimes when leaving I leave that coil on the ground since I don't have the second hand available and I am in a hurry.

    Generator wise: It all depends on the load calcs on the generator, etc... I am not 100% sure why Tesla says not to do it. Likely because they are worried about bad quality power on smaller generators. 22kW is pretty big though. I had my Tesla connected to a 30kW genny yesterday (was load banking the genny) and it worked fine (though I was only doing 16a at 120v since that was the only receptacle available). I have though about the situation you describe and here is my suggestion: I would not run the Wall Connector through the genny panel since that can be a massive load. I would on the other hand add some kind of receptacle (perhaps up to a 14-50) off the genny that in a real emergency you can plug your UMC into and just dial in the number of amps you think the genny has available. This will likely be my solution when I build my next house.
     
    • Helpful x 1
  13. KenC

    KenC Member

    Joined:
    Sep 4, 2018
    Messages:
    209
    Location:
    Maine
    I have a 12kw GE standby generator, and during one power outage, it charged my Chevy Volt, but that's at 12amps/240v, not 48amps. If the high power draw is the concern, just dial it back. If it's the 5% THD, that these standby generators are typically rated for, then perhaps, consider taking it to a nearby Supercharger instead.
     
  14. eprosenx

    eprosenx Active Member

    Joined:
    May 30, 2018
    Messages:
    1,697
    Location:
    Beaverton, OR
    So I am curious about whether the power quality from various small generators is good enough for a Tesla. The thing is, the Tesla is a pretty easy load in a lot of ways. It is just rectifiers, and it is electronically controlled so it ramps in the load relatively slowly (as opposed to an electric motor with a huge surge current). I would expect it to be a power factor corrected power supply (so pretty close to power factor one). Though I wonder if there are any weird harmonic issues or anything? I know that in large datacenters historically they have had 480v generators that were then stepped down to 208v. But then Facebook built a datacenter with 277v servers and they had issues with the generators. I think their solution was 480/277 to 480/277 isolation transformers (so no voltage change, but just isolation).

    I would like the ability to charge my car in a true emergency off my home generator in my next house. Desperate times call for desperate measures sometimes...
     
  15. drawfour

    drawfour Member

    Joined:
    Mar 10, 2018
    Messages:
    778
    Location:
    Seattle, WA
    Washington State follows 2017 NEC without modifications, at least according to NEC® adoption maps - NFPA. My electrician put a 14-50 outlet on a 40-amp circuit, and did not install a GFCI breaker, and the outlet is not GFCI either. That circuit just passed inspection today, and the inspector unplugged my UMC from the outlet before he inspected it, so he knew it was for an EV.

    So YMMV on needing a GFCI.
     
  16. Toadmanor

    Toadmanor Member

    Joined:
    Nov 22, 2016
    Messages:
    43
    Location:
    Minnesota
    I have GFCI as part of my 50 AMP breaker with a 6/3 NM-B hooked to a 14-50. Periodically the breaker trips. Someone thought perhaps the GFCI part of breaker is broken. The car (M3) doesn't pull more than 32 AMPS so that can't be tripping it.

    Any thoughts or ideas?
     
  17. eprosenx

    eprosenx Active Member

    Joined:
    May 30, 2018
    Messages:
    1,697
    Location:
    Beaverton, OR
    It was a last minute "emergency" addition to the 2017 NEC. Many (most?) inspectors don't know the requirement is there. It is at the end of NEC Article 625. Many get away without requiring it.

    I personally think it is dumb for 14-50's installed indoors in garages... The EVSE has a GFCI built in, so the risk is only in the 12" from the receptacle to the UMC. The real risk is plugging / unplugging the UMC in the rain. The car end is GFCI protected by the UMC so that is fine to be wet.

    Yeah, 32 amps should not be blowing it. Does it give any indication if it blew due to GFCI vs. due to overload? Or is it just a tripped breaker either way? (the combo AFCI / GFCI ones sometimes have flash codes to tell you which tripped it)

    I would check to make sure the wire connections at the breaker end are tight. Loose connections could cause heat buildup and be tripping the breaker.

    You could also have a bad UMC or car that is leaking current to ground, but that seems unlikely. Much more likely that the GFCI breaker is bad - GFCI's are notoriously bad at going bad. Sadly though, the big breaker ones are like $100 to replace! How long ago was it installed? Maybe it is under warranty still or can be returned to the place of purchase...
     
  18. Toadmanor

    Toadmanor Member

    Joined:
    Nov 22, 2016
    Messages:
    43
    Location:
    Minnesota
    @eprosenx Thanks for helping. No, it does not give any indication of what trips it. The wiring was just hooked up to the breaker two days ago and it was torqued pretty hard so I doubt that loose wiring is the issue.

    I am also thinking the breaker is bad. The house was built in 2008. Can they go bad that soon? I am aware of the high cost but also wonder if I need to get another GFCI breaker. Would a standard 50 AMP breaker do the trick? The potential problem with that however, is that IF the GFCI fault is real and I install a standard breaker what might the potential downside be?

    I wish there was a way to "test" the breaker. I have pushed the "test" button and all behaves as one would expect.
     
  19. eprosenx

    eprosenx Active Member

    Joined:
    May 30, 2018
    Messages:
    1,697
    Location:
    Beaverton, OR
    I am confused, it was just hooked up two days ago, but the breaker was from 2008? Was it previously for a spa or something?

    Where is the receptacle located? Inside or outside? Could it even be wet in the location you plug it in?

    We see people report issues with GFCI outlets all the time on the forums, but normally they are older units and replacing them does the trick. But if this is a brand new bereaker that is interesting. Frankly, not many people have 50a gfci breakers. This was not a code requirement until 2017 code was adopted. The failure rate on GFCI units is astronomical.

    So I personally would have no issues swapping that breaker to a non-gfci one if the receptacle was in a non-wet location.

    Just think- I have never seen a 50a RV receptacle with GFCI out there and there are tens of thousands of receptacles in the USA.
     
    • Helpful x 1
  20. Toadmanor

    Toadmanor Member

    Joined:
    Nov 22, 2016
    Messages:
    43
    Location:
    Minnesota
    @eprosenx Once again thank you. Yes, the breaker is from 2008 when the house was built. It was originally for a Hot Tub which I have removed a couple of years ago. The breaker was turned off for a couple of years and I have now just wired the 14-50 into that breaker after unwiring the run that went to the Hot Tub. The breaker and panel are located in my basement which is dry.
     

Share This Page

  • About Us

    Formed in 2006, Tesla Motors Club (TMC) was the first independent online Tesla community. Today it remains the largest and most dynamic community of Tesla enthusiasts. Learn more.
  • Do you value your experience at TMC? Consider becoming a Supporting Member of Tesla Motors Club. As a thank you for your contribution, you'll get nearly no ads in the Community and Groups sections. Additional perks are available depending on the level of contribution. Please visit the Account Upgrades page for more details.


    SUPPORT TMC