l6sman wrote: ↑
Sun Dec 27, 2020 9:03 am
OK thanks. Then does it hurt using the original Nissan charger since it seemed to work fine?
To my knowledge, the only hazard the NEC is seeking to avoid with the requirement of a maximum 80% continuous load on a breaker is the hazard of repeated nuisance tripping. This is a real hazard, as if the user gets in the habit of just resetting the breaker, then the breaker will wear, and the user will not be able to tell if it starts tripping for some other reason.
Also, I believe you mentioned that your garage is fed by a 30A 120V/240V circuit, and that it has other loads. Even if your breaker holds with the continuous 27.5A load of the Nissan Leaf alone, there is a significant probability of it tripping when other loads happen to come on. I.e. just because you tried the garage door opener once doesn't mean that there isn't a 1% or 5% chance of it tripping each time you use the garage door opener. Sticking with the 24A continuous EVSE would give you more headroom.
Lastly, I don't know what pilot signal the Nissan EVSE uses. If it advertises 30A or 32A, and you ever plug in another EV that can charge at that rate, you're quite likely to trip the 30A breaker.
So for those reasons, it is more prudent to use the 24A continuous EVSE, rather than the Nissan EVSE.
PS For those less familiar with the NEC, the requirement for continuous loads is written in terms of providing conductors with an ampacity (amp capacity) of 125% of the continuous load. Which at first glance suggests that the conductors themselves are in need of upsizing for continuous load. But basically every instance of this requirement has an exception stating that if the circuit is supplied by a "100% rated" breaker, then the conductors may be sized at 100% of the continuous load. A "100% rated" breaker consists of a single breaker in its own enclosure (to avoid heat buildup from other breakers) that has been tested to hold at a continuous current matching its rating. [And they basically don't exist smaller than 100A.] This shows that the continuous load requirements are due to the limitations of standard breakers, and nothing else.