I'm not a fan of this:
Using a circuit breaker as a switch, especially the older ones, can lead to early wear of the contacts and spring that
could reduce the effective current handling. More modern ones are less likely to suffer from this kind of wear but they are pricy:
https://www.mikeholt.com/mojonewsarchive/NEC-HTML/HTML/ElectricalCircuitBreakers~20020419.htm
Likewise in a parallel manner; we say that a circuit breaker can control and protect an electrical circuit. An electrical relay is an example of an operating control; it opens and closes the circuit. Circuit breakers are not designed as replacements for relays, operating controls.
There is as you may intuitively have anticipated an exception. Some circuit breakers are manufactured for use in a specific type of application. When a circuit breaker is designed to also be routinely used as an on-off switch to control 277 volt florescent luminaires they are marked SWD, for switch duty. This does not mean that a switch duty breaker can be used to manually control a traffic signal light where it will be cycled 1,000 or more times per day. The point is; the listing for switch duty (SWD) does not mean a circuit breaker can be used as a high frequency cycling operating control, such as a relay that has a life span rated in tens, if not hundreds of thousands of duty cycles.
While circuit breakers can be legitimately and safely used as switches, the frequency and duration of such use is very limited. Routinely circuit breakers are manually operated for service-maintenance, and repair type activities. With the preceding enhancing our understanding; we can say that circuit breakers can legitimately be used as switches, generally they are not intended for prolonged frequent or repetitive manual breaking and making type control of electrical energy utilization equipment.
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My experience is that the current limit of a circuit breaker tends to decrease the more often it cycles. When they trip or are switched, there is a
tendency to 'arc' and that pits and oxidizes the contacts. This can lead to warmer operation and a lower current. Of course there are circuit breakers that are designed to be switches.
The safest way is to disconnect the plug from the car as this first opens the "presence" line, a no power signal line. Both the car and the EVSE will take power off safely and minimize any relay contact arcs. An equally valid approach is to command either the car or the EVSE to stop charging. Again, the power is taken off first.
GOOD LUCK!
Bob Wilson