Figure 6-19.Isofootcandle curve.
Figure 6-20.Roadway perspective view.
For lighting extended vertical surfaces, such as
smoke stacks or towers, mount floodlights so distance
between floodlights or groups does not exceed twice
the distance from the floodlight to the illuminated
4. Class OISame as Class O except with an
auxiliary inner reflector to modify the beam
The suffix letter B should be added to the above
class designations to indicate when an integral ballast
Use a smaller number of large floodlights
Example: A heavy-duty floodlight with an integral
instead of a larger number of smaller floodlights.
ballast would be designated as a Class HDB floodlight.
SELECTION OF LUMINAIRES
The National Electrical Manufacturers
Association (NEMA) has classified floodlighting
luminaries into four classes according to construction:
1. Class HD (Heavy Duty)Enclosed with an
outer housing into which is placed a separate and
removable reflector, or an enclosure in which a separate
housing is placed over the reflector
2. Class GP (General Purpose)Enclosed with a
one-piece housing with the inner surface serving as a
reflector and the outer surface being exposed to the
3. Class O (Open)One-piece housing without