I want to install a 40A electric vehicle charger (probably a ClipperCreek HCS-50) in my unfinished attached garage in the Puget Sound area of Washington State. I intend to have this inspected and permitted, but it's been a good learning experience in a variety of ways already.
I haven't installed a branch circuit before, but this seems about as dirt-simple as it could get: the location I'd like to put the EVSE is about 20 feet away from my service panel, which has open slots on it and sufficient extra capacity in the 200A mains breaker.
To do the install, I've purchased 25 feet of 6/3 NM-B (ampacity 55A) and a 240V 50A breaker that matches my panel brand. I will run the 6/3 along the same path of already drilled holes in the exposed studs to the point where I'll put a NEMA 6-50 receptacle.
- I'm not clear on whether it's necessary to have a bushing on the entrance to the box where the receptacle will go, but intend to add one to err on the side of caution.
- I believe the routing through the studs means that I shouldn't need any further protection from physical damage. I think the hole bored through the stud counts as supports, but the cable will still need to be secured within 12" of each end. I'm not sure how proscriptive this is, but I'd like to use screw-in cable guides similar to this:
- The path of the cable is near EPS insulation, but there's only one cable there now, so 310.15(B)(3)(a)'s adjustments shouldn't apply.
- It's indoors, it's a dry location, so normal NM-B is sufficient.
Are there any major obstacles I haven't accounted for, or any likely gotchas that I'll hit during an inspection?
This is similar to the question Questions regarding my plan for new 50A circuit (with pictures), but I believe it's sufficiently different to merit its own question.