All of the outlets in the room are running off of one circuit, and while it's important not to overload a single outlet, you should never exceed the rating of the room you'll be growing in. I'm sure there are plenty of people who could give you much more detailed information about circuitry, overloading breakers, etc., but you should be just fine running a 600W light, plus all the fans & other utilities you'll need in that room. If you are unable to plug the utilities directly into outlets in the room, make sure that any extension cords you use are thick and rated for the wattage that you'll be pushing through them. I have two industrial sized power-strips (surge protectors) that feed from two different electrical outlets. I'm not sure what the gauge of the power wire is, but it's a freaking monster...and never gets hot. One would be more than enough to run just about all of my utilities, but I use two for good measure.

Make sure that you don't have cords & power strips scattered all over the floor of the area you're growing in. This can be a trip hazard, and can also become an electrical hazard if water is spilled around them. Most surge protectors have slots in the back of them that can attach to screws/studs in the wall. I keep all of my electrical components (ballasts, fans, lights, etc.) suspended as well as all of the correlating power cords & power strips. No mess, and if there is a spill, I simply just mop it up...as opposed to freaking out about whether or not I'm going to be electrocuted the next time I plug something into an outlet. Or worse yet, starting a fire and possibly killing my family. I take these things very seriously, and always make sure that safety comes first...even if it hinders functionality.