For common flood lights, the height can be 2.24-2.65 meters. And if you want brighter light, you can shorten its distance from the ground to 1.5-1.7 meters. As for those flood lights that light up the outside corridors, the height should be about 1.8 meters above eye level. And the distance between the light and the wall should be about 0.1-0.4 meters.
More reading: Height of Street Lights: How Tall Should They Be?