EV Charging Approach - Difficult Choice

Status
Not open for further replies.
Here's another question that arose. Running SE 6/3 in the ceiling: Can I transition from ceiling cavity to PVC conduit along an inside wall of the garage and then run conduit through wall to exterior Tesla Wall charger. I assume a bushing at the conduit entrance in the ceiling, proper straps along wall and an LB body at the turn to the outside through wall are sufficient. The client has a Tesla and I think that that charger is appropriate for them.
 
Last edited:
ESolar said:
Here's another question that arose. Running SE 6/3 in the ceiling: Can I transition from ceiling cavity to PVC conduit along an inside wall of the garage and then run conduit through wall to exterior Tesla Wall charger. I assume a bushing at the conduit entrance in the ceiling, proper straps along wall and an LB body at the turn to the outside through wall are sufficient. The client has a Tesla and I think that that charger is appropriate for them.
Click to expand...
1657750747688.png
 
ESolar said:
FYI: The Tesla wall charger is GFCI.
Click to expand...
It's not, actually. EVSEs have some ground fault protection or other mechanism, but I don't believe it necessarily meets the same standards as a GFCI would. Also, if the outlet is required to be GFCI protected, the unit's protection is downstream of the outlet, so is immaterial for protecting the outlet.

But CA hasn't adopted the 2020 yet, so if the EVSE is hard-wired, you don't need GFCI protection for its outlet.

Cheers, Wayne
 
wwhitney said:
Also, if the outlet is required to be GFCI protected, the unit's protection is downstream of the outlet, so is immaterial for protecting the outlet.
Click to expand...
That's splitting hairs way too much. If a GFCI receptacle meets the requirement then so does any utilization equipment with built in GFCI.
 
wwhitney said:
(2020) 210.8(F) requires it for outdoor outlets, but in a garage, I don't see anything in 210.8 or 625.54 that would require GFCI for a hardwired EVSE.

Cheers, Wayne
Click to expand...

True. It’s not uncommon for EVSEs to be installed outside. I don’t think that’s the case with the OP, but we’ve strayed so far from his original question, we should consider it as well.
 
jaggedben said:
That's splitting hairs way too much. If a GFCI receptacle meets the requirement then so does any utilization equipment with built in GFCI.
Click to expand...

I don’t agree. The most common case that the GFCI protects against is incidental contact when plugging / unplugging at the receptacle. GFCI in the equipment doesn’t protect this.
 
jaggedben said:
That's splitting hairs way too much. If a GFCI receptacle meets the requirement then so does any utilization equipment with built in GFCI.
Click to expand...
Perhaps that would be a logical or fair result, but the NEC definition of outlet is clear. GFCI in utilization equipment (which we don't actually have in this case) does not protect the outlet, whether that's a receptacle or a hard-wired connection.

Cheers, Wayne
 
retirede said:
I don’t agree. The most common case that the GFCI protects against is incidental contact when plugging / unplugging at the receptacle. GFCI in the equipment doesn’t protect this.
Click to expand...
There's no plugging and unplugging involved in what we're talking about. To be clear, I only meant to refer to hard wired equipment with GFCI. For a receptacle that could have anything plugged into it, I agree the code requires GFCI now.

wwhitney said:
Perhaps that would be a logical or fair result, but the NEC definition of outlet is clear. GFCI in utilization equipment (which we don't actually have in this case) does not protect the outlet, whether that's a receptacle or a hard-wired connection.
Click to expand...

210.8 is completely vague about the location of the GFCI protection and says nothing that prohibits it from being at or in the utilization equipment. Also the simpler EVSEs don’t meet the definition of utilization equipment any more than a GFCI receptacle does. The real utilization equipment is the car.

There are already enough reasons that people install EVSEs without permits, we really don't need to add such a ridiculous overinterpretation to them.
 
wwhitney said:
(2020) 210.8(F) requires it for outdoor outlets, but in a garage, I don't see anything in 210.8 or 625.54 that would require GFCI for a hardwired EVSE.
Click to expand...

Note that the outdoor outlet requirement doesn't apply to >50A circuits. So even in the strictest interpretation, 48A (60A breaker) or higher EVSEs are exempt.
 
jaggedben said:
210.8 is completely vague about the location of the GFCI protection and says nothing that prohibits it from being at or in the utilization equipment.
Click to expand...
GFICI downstream of an outlet can't possibly protect that outlet. The outlet on hardwired equipment is the junction between the branch circuit wiring method and the utilization equipment in its wiring compartment. Maybe if that wiring compartment has a GFCI device on which you terminate the branch circuit wiring, it would meet the definitions and requirements for protecting the outlet.

jaggedben said:
Also the simpler EVSEs don’t meet the definition of utilization equipment any more than a GFCI receptacle does. The real utilization equipment is the car.
Click to expand...
That is a very good point. If you call the hardwired EVSE part of the premises wiring system, then the outlet is the J1772 connector.

Cheers, Wayne
 
wwhitney said:
GFICI downstream of an outlet can't possibly protect that outlet. The outlet on hardwired equipment is the junction between the branch circuit wiring method and the utilization equipment in its wiring compartment.
Click to expand...

The problem here is that you're insisting that the intentionally vague and overbroad definition of an outlet is narrower than it actually is, and all to support an illogical conclusion with no safety benefit. 210.8 states that the purpose is to protect personel, not the outlet or wiring or equipment connected to it. GFCI at the input of a hard-wired EVSE meets that requirement.
 
jaggedben said:
The problem here is that you're insisting that the intentionally vague and overbroad definition of an outlet is narrower than it actually is, and all to support an illogical conclusion with no safety benefit. 210.8 states that the purpose is to protect personel, not the outlet or wiring or equipment connected to it. GFCI at the input of a hard-wired EVSE meets that requirement.
Click to expand...
I agree with the above except that idea that the definition of outlet is vague or overbroad. But then again as a mathematician I expect precise definitions. Seems to me like the 210.8(F) wording just needs to be tweaked a little to cover the case you describe.

Cheers, Wayne
 
Great discussion re EV charging. I have concluded that the circuit from the subpanel is not an option at 40amps because the feeder to the subpanel is #2 aluminum SER feeding through walls. Please comment on my conclusion. The terminations, etc., are 75 C (90 amp rating), but the SER was run through the walls. With insulation contact that wire has a 60 C, 75 amp rating. The breaker is 70 amps. The panel supplies general lighting/recepatacles to approximately 1,700 sqft (19 amp demand at 3VA/sqft), an air handler (assuming 6 amps at 1,500 watts), and a central vacuum (12 amps name plate). The 20 amp garage circuit is also on that panel - but my understanding is that that would not figure into the load calcaultions. By my calculations the total existing load is 37 amps. And that assumes that nobody plugs in a space heater or other high amp device. That only leave 33 amps for the EV charger. For sizing the EV circuit I was using 32 amps (on 40 amp breaker). But I should have been using 40 amps (125%). So by my calcs the max amperage for a charger on that panel is 24 amps (30 amp breaker). (One lesson - up size the wires when installing subpanels).
 
jaggedben said:
210.8 is completely vague about the location of the GFCI protection and says nothing that prohibits it from being at or in the utilization equipment. Also the simpler EVSEs don’t meet the definition of utilization equipment any more than a GFCI receptacle does. The real utilization equipment is the car.
Click to expand...


wwhitney said:
That is a very good point. If you call the hardwired EVSE part of the premises wiring system, then the outlet is the J1772 connector.
Click to expand...
Agreed the utilization equipment is the car, the EVSE is the outlet, thats why its best to hard-wire those, and avoid the double GFCI issue.
 
I suppose given that limitation I could also propose this option: Wire a pigtail 10-30 plug to a Tesla Wall Charger and run through wall to plug into existing dryer outlet. Seems like there there would be/should be some kind of code violation here, but I can't identify it. Leaving 10-30 intact means that no upgrade is required.
1657816744265.png
 
ESolar said:
Great discussion re EV charging. I have concluded that the circuit from the subpanel is not an option at 40amps because the feeder to the subpanel is #2 aluminum SER feeding through walls. Please comment on my conclusion. The terminations, etc., are 75 C (90 amp rating), but the SER was run through the walls. With insulation contact that wire has a 60 C, 75 amp rating.
Click to expand...
That last sentence was true for all sizes for 1 (or 2?) code cycles in the past, but in the current NEC (2017 for CA), the limitations is only for #10 and smaller. See:


So you can use the 90A rating and upsize the feeder breaker accordingly, unless there is further derating by a factor smaller than 0.9 (90C ampacity is 100A).

Cheers, Wayne
 
wwhitney said:
That last sentence was true for all sizes for 1 (or 2?) code cycles in the past, but in the current NEC (2017 for CA), the limitations is only for #10 and smaller. See:


So you can use the 90A rating and upsize the feeder breaker accordingly, unless there is further derating by a factor smaller than 0.9 (90C ampacity is 100A).

Cheers, Wayne
Click to expand...
So that #2 Aluminum is good for 90 amps? What do you mean by "Unless there is further derating by a factor smaller than 0.9?"
 
Status
Not open for further replies.
Top