a small bedroom is 15 amps. any electrician with his head not up his ass would never waste a 20 amp breaker on a bedroom circuit.
rule of thumb- 1440w of grow equipment per dedicated #14awg cable, 15 amp breaker, max.
1920w of grow equipment per dedicated #12awg cable, 20 amp breaker, max.
2880w of grow equipment per dedicated #10awg cable, 30 amp breaker, max.
those wattages are good for 120v only. it changes if your going to go 240.
and ps- those numbers are factored for continous duty operation. dont play with them. i know you can get more wattage out of the breakers, but if you try to run them with higher wattage than i posted above, the breaker will heat up and trip after a cpl of hours.
stick with those numbers and you cant go wrong.