Power Peak, when is too much?

In 1 room, how many lights can be ran in the standard 120volt outlet? I'm running 1 400 plus many fans, and a fluro. If I add a 600 watt light will the breaker go off? What do you do?

I believe standard household wiring in the US is 15 amp, but a breaker will trip if it's run at more than 80% of it's rated load for any length of time, so figure 12a. 12x120 = 1440w, your absolute maximum. If you add up the wattages of everything and it's getting close, I'd seriously think about running another line in there, to leave a bit of breathing room, and in case you want to add anything else.
Makes me feel lucky to live in UK, we get 240vx13a = about 2500w per circuit.

Bummer, how on earth are people running 2 1000 watt lights, and fans? I want to upgrade, but I am a renter and can't alter the electricity.

It's a fairly simple job to run a length or two of 20-30amp cable to your breaker box, depending where it is in relation to the room, so long as you own the property (or have a sympathetic landlord)
You could always run an extension from a bedroom or something to get a bit more juice in there. I'm not sure how it's done over there but in UK each room tends to be on it's own breaker, so if you do do that, don't run it from a room that might have high drain appliances like heaters or hairdriers running in it.

your 600 and 400 are fine on a standard 15a circuit, even a few low wattagen fans will be cool on there....assuming that its only running that room but in reality you need to add a circuit http://www.youtube.com/watch?v=sjbLYNePQGA check out this youtube video i did of my setup, im a renter also and i added a 20 amp circuit to my grow room with only putting a quarter sized hole in the wall that i can patch real easy when i move, in my setup i run 2 600's on their own 20a circuit then my fans and stuff are run on the 15 amp one that is standard in the room

Also keep in mind that a breaker will feed a few outlets. And not always one breaker per room.