The actual power is 120 W per fixtureCan get close enough to burn the leaves then its too close! 6-10" is about as close as I can get.
2400 watts in a 4x4 is a lot of light. Likely they are not drawing 1200 watts from the wall socket per light.
A 15A circuit is only 1800w so you wood be blowing fuses if they were on the same circuit.
Suggest checking the specs of you lamps and figure out the wattage "at the wall" or actual wattage draw. Anything close to say 1500w total on the same circuit will trip the breaker at start up if they both start at the same time (timer) and likely burn out your timer eventually.
To answer your question. Pin the lamps to the ceiling as high as they can go. Put a clip fan up there to keep the air moving. When/if the plants grow up to them, train the plants using LST and/or super cropping the tallest leaders.
To give you an idea how far you can go. I run about 800w at the wall in a 4x4 space with extremenly efficient LED lamps. I'm at max lighting without Co2 augmentation tho.I will have two of these fixtures in the 4X4 area