You best figure out if they are all on the same circuit. Likely they are. You mostly run into problems with amperage, not wattage. Most household circuits are 15 amp, but there is a possibility of them being 20 amp. It's easy to tell just by looking at them. But if your using a digital ballast, they use 5.7 amps each. You generally want to be a little under the limit of the circuit just to be safe, ie you dont want to run exactly 15 amps on a 15 amp circuit continuously but around 13 or so.
So yes, if your using digital ballasts, then you can't use all 4 in that room.