Oh, okay. Don't really hear of people doing that but I guess in theory it's safer. Normally you think of the purpose of a circuit breaker as protecting the house wiring and receptacles from a device or devices overloading the circuit beyond its capacity, not protecting the devices plugged into the circuit (unlike GFCI which is designed for that purpose). I mean we plug in 18 gauge lamp cord into 15 amp circuits, which is kind of the same thing. Although I understand with 50 amps the power level is higher, but then again the EVSE does not use lamp cord it is using much higher gauge wiring, so it probably becomes relatively the same situation. Obviously if the 20 amp circuit breaker is still in there when you sell the house you will need to install a 50 amp breaker otherwise the next owner will plug in their EV and wonder why the circuit breaker keeps tripping, but I'm sure you already plan to do that. Anyway thanks for clearing up what you are doing.