I am having an electrician install a hardwired 50 amp Level-2 charger in my garage. A NEMA plug based charger on 50 amp circuit can only charge at 40 amps or so, but if you hardwire you can use full capacity of charger. So far, charger vendor and electrician agree on that.
However, charger vendor says that #6 copper and 60 amp breakers are sufficient because the car charger is “like a hardwired welder” but electrician’s interpretation of code is that we should use #4 and 70 amp breakers. Extra cost of wire needed is maybe $200, given sky high copper prices.
I am inclined to play it safe and go with electrician’s interpretation of code, since why burn house down to save $200, but interested if any electricians have more experience with hardwired chargers and code requirements,
PS - I have ordered a Primecomtech 50 amp charger because the pre sales support and question answering were so good. Chargepoint did not answer my emailed pre-sales questions while the Primecomtech guy emailed right back and also took a phone call from my electrician (!). I checked out Chargepoint reviews and saw complaints that the lugs you have to hardwire to can only handle max #6 wire, and some reviewers were insisting this means you cannot meet the code for a circuit with 50 amp load. But maybe Chargepoint knows about the “hardwired welding circuit” It seems like a welder would be intermittent use while charger would be 50 amp draw until car battery gets to 80%.
Finally, there is 30% credit for installation cost of level 2 home charger up to max of $1000 (the credit) good through end of 2021. This is why we are doing charger now, buying car later, Also the charger install is a piece of upgrade from 100 amp to 200 amp service, making it easy to get the max credit.
I’m an electrician without ev charging experience.
Your electrician is correct that if you want 50a continuous you’re gonna need the #4’s, 70 and a hardwired connection to be compliant. Lockable disconnect may be required. If this is going to be in an enclosed space then ventilation may be required and would probably be a good idea anyways.
Definitely heat. The faster you pump electrons into the battery, the more heat is generated. Higher voltage/amperage means more wasted energy (i.e. the heat), so if you can get away with a slower recharge, it’s best to do so. Also faster charging degrades the battery more.
It’s to prevent the accumulation of an explosive amount of hydrogen gas that comes with charging lead acid batteries. Ventilation and hydrogen gas detectors are required for battery rooms elsewhere in the same code.
Even if they don’t still use batteries that off-gas in EV’s(I have no idea if they do) they probably did when the code was written.
As with everything NEC there are various exceptions, limitations and interpretations for different circumstances, conditions, occupancies etc and it changes every three years. To make it more confusing many jurisdictions make their own amendments and sometimes choose to continue enforcing the older versions instead of adopting the latest.
You’re local electrician should know what’s required in your area and should also know what your local inspectors are enforcing.
Plug in EV’s and Plug in Hybrids use Lithium batteries, not lead acid, so I don’t think hydrogen gas is issue with charging in confined space. Car will be in attached but unheated garage.
The charger is represented as capable of 50 amp charging, not 48. Going with the 70 amp and #4 anyway so we aren’t planning to skimp even if vendor claims 60 amp and #6 is sufficient.
Maybe they don’t use lead acid but if there aren’t exceptions to any ventilation requirements triggered(and there may be) then that doesn’t matter from a code perspective.
If there is a discrepancy between the manufacturers documentation and the code requirements the most conservative option is usually best, if not for functional reasons than for practical reasons.
See above. The charger appears to be capable of being internally configured to various charging amperages, including both 48A and 50A. The former requires a 60A breaker, the latter requires 70A.