No dedicated circuit is needed, but it should be on a 15 A breaker and if the circuit is shared with other loads, make sure the total does not exceed more than 3A while you are actively charging the car. The car uses 12A max while charging. If you have a smaller 10A breaker or must use more Amp for other electronics, then you have an option of charging your car at 8A by setting the charging amp on your car. I use a 120v outlet in a circuit on a 20A breaker, but it is shared with a full-size freezer and several lights and garage door openers. I have not had a breaker trip in the last 5+ years.
In addition to this, It would be nice to know what else is on the same circuit your plugging the car into - to avoid popping your circuit breakers. This can be accomplished by using a 'fox & hound' circuit tester - . This way you'll know what circuit breaker to go after and what appliances to move off of the circuit, when your car is charging.
It is not required. ONLY RECOMMENDED. While a dedicated circuit would be safer, IMHO, similar to the use of an extension cord, with care, it is fine to use a common circuit shared by other outlets/electronics. I never installed a dedicated circuit. As I stated, I have been using on 20A circuit to outside and garage shared by other outlets with actively connected to several electronics.
