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Ground fault protection a new complication for EV charging?

Discussion in 'Model S: Battery & Charging' started by Plugsuvohio, Mar 30, 2017.

  1. Plugsuvohio

    Plugsuvohio Member

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    I'm finishing up installation of myTesla "HPWC" that among other things gets me 48A charging vs 40 I've used on that circuit with a traditional NEMA 14-50 outlet that most of use us. In walks the electrical inspector (I had a permit) and we start talking about electric vehicles and charging them. This is the first such outlet he has run into. I explained that 120V charging is entirely impractical for plug-in automobiles, not to mention small trucks and other vehicles which are coming to market.

    He starts scratching his head, and says "You know the National Electric Code is changing so that ground fault protection is required for 208/240 outlets" HUH?? :mad: He could not quote me details, but before he gets back for a final, I better know the answers. So I'm doing internet searches and finding a hotly contested matter going on last fall 2016. Apparently the EV manufacturers have made it clear that higher amp and voltage charging is more and more needed. And if this regulation quickly goes into effect and adoption by each state's own code - it will greatly impact selling EV not to mention confuse those who want to buy an EV; set up home charging; or set up destination charging all over the place. In essence any new installation (like the outlet you need for your shiny new EV on the way) will have to be protected like those in a kitchen, bathroom or outdoor outlet. If you use a cable with plug on the end into the wall outlet, this is you.

    Sounds like the electrical safety people, fire protection people, Underwriters Lab, etc are not in agreement about this. Supposedly this requirement had already gotten into the code for residential applications, especially when outdoor or damp locations. Due to some uproar, the mandatory Ground Fault Interrupter circuit got removed as a requirement. I'm not sure about other locations than homes. As a retired engineer, I do have some familiarity with circuits and electrical installation both home and commercial at my business. As I plan to travel lots with the Tesla, I don't want to rely on Supercharters. Destination charging is a must.

    Does anyone out there know the real skinny ? This means if you bought a "charger" with a line cord (like most on the market) it would not be legal to plug it in without your electrical panel also providing ground fault (tiny current leakage) protection. It is not clear whether fully hard wired systems require this same new code.

    We never needed this for our dryer and portable arc welders at 240V for instance. Why now force this on EV owners? How come the EV manufactures are not mentioning this when selling, or in the installation/operation manuals too? :confused::confused:
     
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  2. ColdRauv

    ColdRauv Member

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    I believe the requirement for GF protection is for receptacles up to 50A in non-dwelling locations, not your home. Effective whenever your jurisdiction adopts the 2017 NEC.
     
  3. Mach Schnell!

    Mach Schnell! Gearhead, Engineer & P100D(L) Pilot

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    Even if true, what's the big deal? At least for 50A charging circuit requirement, 240V, 50A, 2pole GFI circuit breakers are common, can swap out existing breaker, and cost under $100. I had to put one in when I wired my spa. Square D Homeline 50 Amp 2-Pole GFCI Circuit Breaker HOM250GFICP at The Home Depot - Mobile. Maybe I am missing something?
     

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  4. Plugsuvohio

    Plugsuvohio Member

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    I realized I left out another part of the concern. If you did install a GFI protected outlet, such as suggested by swapping out the main panel breaker, you wind up with 2 GFI systems in series. The one from the panel and another which is a function with the EVSE (electric vehicle service equipment) like Tesla's mobile cable or the HPWC. What I have heard is that such an arrangement is subject to a lot of nuisance tripping. I'd hate to wake up and go to work and find I'd not gotten the charging I expected overnight due to false tripping.
     
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  5. Mach Schnell!

    Mach Schnell! Gearhead, Engineer & P100D(L) Pilot

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    I agree with you. Don't want nuisance tripping!
     
  6. FlyingCookie

    FlyingCookie Member

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    So if the GFI is already built into the device that is required to plug into the vehicle, would it still be required to use a GFCI breaker on a panel serving a HPWC?
     
  7. gregd

    gregd Active Member

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    Sort of. The one word to quibble with is "use". When the new code gets adopted, one would be required to install a GFI on new 14-50 installations. But remember it's part of the go-forward code, and there is generally no requirement to upgrade existing installations, nor any issue if you plug your car into (i.e. "use") one of the then-legal outlets that pre-dates the change in NEC code. It's still legal for me to plug my car into the 10-30 Dryer outlet in my garage, for example, even though 10-30 outlets are no longer allowed to be installed.

    As noted earlier, having two GFIs in series can sometimes cause a false trip, but it is generally pretty rare. Mostly you should be fine. I had some trouble with my Roadster tripping the 120v GFI in the garage. Citing the above lore, I removed it from the charging cord. It still trips... So, it was the circuit's GFI itself that was at fault (no pun intended), not the fact that there were two in series. I now have a new circuit in the garage, and that one doesn't trip.
     
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  8. Svandevo

    Svandevo New Member

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    The high powered wall connector has built in GFCI protection. It is not required to have a GFCI breaker.
     
  9. Doug_G

    Doug_G Lead Moderator

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    Correct. In fact, having two of them on the same circuit is likely to result in problems.
     
  10. Plugsuvohio

    Plugsuvohio Member

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    #10 Plugsuvohio, Mar 31, 2017
    Last edited: Mar 31, 2017

    Ok, I've learned a lot more today and while parts of this will make sense because it adding more electrical safety, it could hamper getting more EVs on the road. First, a struggle has been going on for years (like 5) about electrical codes for circuits and electrical code specific to EV charging. The bottom line is that, as on the start of this year NEC 2017 is supposed to be in effect, and during the years up to this specific terms and features where evolving, resulting in a mixture of things on the market, and a mixture of correct code installations made relative to EV charging. While the NEC is a national standard, each state decides what to adopt for their codes, when they decide to make it effective, and even to make more stringent regulations. Then the local jurisdiction like a county or city building department can make future decisions about code, effective dates, and frankly variability in each inspectors decisions being made, The result is a very wide range of things already installed (which were correct at one time) but new work installed is supposed to be different. Then there is the matter of a manufacturer designing and selling a product which complies to various general and specific other standards which further box in what is supposed to happen.

    As of now, only about 2 states have fully adopted the 2017 NEC code. Hawaii for example I think is still using 2009 NEC codes. Here is what you are supposed to do now on new equipment manufactured for EV charge and installation of related circuits in buildings.

    First, a hard wired EVSE is the best approach. It is now termed a "permanent install" It is allowed to go higher amperage at 240VAC, no separate GFI protection is needed at the building panels or outlets, and the EVSE supervises ground fault and leakage not to exceed 20 milliamps. As before you must rerate the circuit to 80% of allowable breaker and wiring size. This is what I call the "gold standard".

    EVSE which have plugs used to connect into building receptacles are the problem areas, especially if they are in wet/damp/outdoor locations. The plug could come loose, terminals become exposed and an unlimited shock hazard results. Also consider that these traditional plugs and receptacles are tested to hundreds of in/out wear cycle testing and heating allowed. (The common 1772 car side connector is required to handle 4000 cycle testing) If you plug it in and leave it, the risk and wear out is very low. In and out every day is another story. So now compromises and limitations are being leveled, in particular to 240VAC input "portable" or "stationary" EVSE use.

    You may make and correctly install a stationary EVSE with a 12" cord and plug into a wall outlet. It can he hung on a bracket. BUT it is only to be unplugged to allow for maintenance, moving to a new position on rare occasions. This circuit (in the US with NEC 2017 now) MUST have a GFI at the breaker or the outlet with only 5ma trip level which was not previously the case. But the EVSE still has to have GFI internal and it is allowed to allow 20ma trip. So in essence, it is the 5ma safety device still controlling. Electronic circuits create ground fault line imbalances of a couple of ma on their own, taking up some of the safe margin. Plug your connector then into a vehicle and that level always increases depending on moisture and the charging device in the particular vehicle. More margin used. More potential for a nuisance trip even though there is actually little or no true leakage hazard. Today we set up a test with my soaking wet Model X in the rain, the tesla supplied mobile cable (2017 obsolete terminology) and regular 240VAC wire, conduit and breaker in an auto shop. Measured about 0 ma with nothing plugged in at the receptacle; 1 ma with the powered EVSE and cord but cord indoors and not connected on the vehicle end. Then I inserted it to start charging. It jumped briefly to about 8 ma and quickly lowered and became stable at 1.7 ma. So in theory, this would not have tripped what would typically be a 5ma GFI on the building circuit. Good for Tesla and a relatively new cable. We had professional level instruments attached to measure all this. But all installations are not likely to be this good and other design vehicle on-board charge systems not this good. So to refresh: New work installation for this under 2017 NEC MUST have the 5ma GFI; EVSE will have a 20ma GFI (effectively doing nothing); and our Tesla are likely to be free of nuisance trips.

    HOLD on however. Under new rules NO circuit feeding an EVSE "PORTABLE" classified EVSE can exceed 20A at the traditionally 208 or 240V level. Of course you must still derate a continuous loaded circuit like an EV to 80%, so the EVSE would not be allowed to provide over 16 Amps ! As I see it, Tesla could no longer provide you, in the US, the 40A unit that comes with the vehicle. The impact on charge rate is obvious, Not good.

    So has anyone out there seen changes in what is provided with New Tesla S or X? Has Tesla announced anything? Am I totally wrong?

    The Bolt and Ford plug-in only come with level 1 (120V) PORTABLE cables. The PORTABLE cable must be agency tested to handle -30deg impacts, being run over, high moisture levels, etc. It had not been this severe under the recently obsolete NEC called "MOBILE" connector EVSE equipment !

    Residential installations get more of a get out of jail free treatment as I understand it; but anything else (outdoor destination charging, commercial locations such as a service garage, store, hotel, public garage, etc) basically will need STATIONARY or PERMANENT EVSE systems and PORTABLE units like we have will be derated greatly as I described above. (Existing installations are grandfathered and we can still use our 40A mobile cables.) Good thing we have Supercharger options and can still charge the same at home (with a somewhat potentially more hazardous shock potential).

    Is Tesla engineering out there somewhere looking at the forums? I'd really like an expert to confirm or correct what I've found out with the new NEC changes.
     
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  11. Cosmacelf

    Cosmacelf Active Member

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    BTW, I believe the 8ma leakage current you saw at charging start was intentional. It is the EVSE testing to make sure that the there is a true ground available.
     
  12. Plugsuvohio

    Plugsuvohio Member

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    More confusing news, I will understand more soon. But a temporary interim action has been passed just following 2017 NEC EFFECTIVITY Jan 1 2017. It essently may remove the limitation for 240v charging which just got into code.



    ll
     
  13. Plugsuvohio

    Plugsuvohio Member

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    Actually they DO require that breaker in 2017 code UNLESS IT IS HARD WIRED"
     
  14. Doug_G

    Doug_G Lead Moderator

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    If it's not hard wired, then sure, I would expect GFI for a garage / outdoor installation. But this can lead to problems because the GFI leakage spec is more restrictive for outlets than what is allowed for EVs.

    If it's hard wired then obviously not needed.
     

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