Pre-wire or conduit for EV charging circuit?

Also, don't forget that not all EVs have the SAE J1772 port in the same location, or even on the same side. Then there is the potential of fast DC charging becoming affordable someday (but I am sure it will be a few more years), but not sure how much prewiring you can do for that.
 
Dan (electron) said:
Also, don't forget that not all EVs have the SAE J1772 port in the same location, or even on the same side. Then there is the potential of fast DC charging becoming affordable someday (but I am sure it will be a few more years), but not sure how much prewiring you can do for that.
 
 
How is this DC charging supposed to work? Is the utility providing it, or do use a charging station to convert you AC current into DC current?  Sounds expensive converting 100amps of AC to DC.
 
As far as I know, there are no residential DC chargers on the marker yet, but now that even Chevy is going to support the Combined Charging System (which supports both Level 2 and Fast DC charging via 1 'connector'), this might change.  I'm guessing you would need some sort of battery based system in order to benefit from the speed.  Not sure how commercial chargers are wired, but they get more than the typical 2-phase residential power source.
 
Anyways, only brought it up in case you are going the conduit route, and want to plan for future tech.
 
I did some googling, it looks like the high amp DC chargers are just for quick charging when on the road, like filling your tank with gas, but instead of 5 minutes it takes 25 minutes.  The cost of those units is pretty high and really only makes sense when it is being used by many people to distribute the costs.  Plus, how often do you come home and only stay a few minutes.  It happens, but usually you come home and stay for hours on end, so why have a super pricey device that doesn't really give you any advantage.  Add that to the fact that the grid going up and down residential streets would need to be upgraded if any number of people own these things, and then there is the generation capacity issues as well.
 
As far as the cable, I think the point is that when you plug the car in, there is a communication that occurs, so the car sets things up to accept whatever current is coming from the charger.  While the super high amp DC charges will undoubtedly use a much higher gauge wire, they will still plug into the same socket on the car, keeping things a little simpler.
 
Like I said, I doubt it's going to be a consumer grade product anytime soon, but charging technology is rapidly changing (Level 1, Level 2, CCS, Nissan's fast DC charging, etc.), and there is competition between various technologies, so in the future, you might have 2 EVs with different charging tech, which might require 2 runs of different cables for 2 different EVSEs (the charger is actually in the car, the unit you mount on the wall just supplies the electricity).
 
Just wanted to make sure there is room for multiple runs of wire, in a safe way, plus the fact that you might want chargers in different locations, depending on the SAE-J1772 port on your car.
 
Had them install a 30A 220v section of romex to a single-gang box on the exterior.  Not live from the panel, but there's plenty of space for it if/when the time comes. 
 
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