Well, I'm not going to bash you here man. I would go and talk with my brother out of respect for his home. Maybe he'll let ya play around with your little personal grow. Hell even if he doesn't smoke he may be interested in seeing how much fun it is to grow this plant. Then you and your bro are on cool terms and you can make way for a little more advanced setup. It's respectful to go this route. Family is more important than marijuana =)
Also, I push a 30 amp grow out of an apartment. I say 30 amps because thats how I personally gauge my electricity usage. I run ALOT of wattage on these two 15 amp breakers. 1000watt HPS, 400 watt MH, 9000BTU AC unit, 2 humidifiers, 1 dehumidifier, 2 inline fans, 5 oscillating fans, 1 T5 clone light, an alarm clock (so I'm not late for work) lol. I'm using about 24 amps out of the 30 with this setup and my bill is about $80 extra a month. Nobody is looking at your electricity bill so long as you pay on time with no hassle.
Oh and if you have to juggle breakers like I do, never let all of your crap kick on at once, Amperage spikes when your ballasts etc kick on then settle at the rated running amperage (for instance my 1000 watt runs 9 amps, but on startup it spikes up to 11.5 amps just to kick start it)
As for your brother, yeah definately have a bro to bro talk with him and let him know you would really like to do this, offer to do the dishes or clean the house for him etc. Make it sound fun and how you promise not to sell it, yadda yadda, I'm sure he would be more inclined to understand =)
Good Luck