My Google-Fu found the following, hope it helps.
From the Texas drivers handbook
6. Additional lights—any motor vehicle may have up to three additional
driving lights mounted on the front—not less than 12 nor more than 42 inches
from the road surface.
And from the Texas vehicle inspection program Clicky
From what I've read, if it's DOT approved, then it doesn't matter what the wattage is. Of course this may change from state to state. California requires off-road lights to be coverd while on-road.