When using ground mounted flood lights to light up a sign, three factors must be considered:
- Setback Distance
- Fixture Spacing
- Aiming Height
Setback Distance
Install fixtures back, "setback", 3/4 times the building height.
Example:
Setback Distance = 3/4 x Sign Height
3/4 x 6 ft. = 4.5 ft.
Fixture Spacing
When spacing fixtures out, do not exceed two times the setback distance.
Example:
Fixture Spacing = 2 x Setback Distance
2 x 4.5 ft. = 9 ft. apart
Aiming Height
Flood lights should be aimed at least 2/3 the height of the building. To reduce unwanted glare, full or upper visors can be installed to the flood light.
Example:
Aiming Height = 2/3 x Building Height
2/3 x 6 ft. = 4 ft. high
2/3 x 6 ft. = 4 ft. high
Source: Lithonia Lighting