1/4" wire glass and ceramic glass are the most
common types of glazing used in fire rated
doors. The hourly rating of the door dictates
the number and maximum size of the vision
lights used in the door. Table 2 shows the
limitations of size, area and number of vision
lights in a door. Vision lights are not allowed in
3-hour rated fire doors, unless allowed by the
local authority having jurisdiction. The vision
light kit or window frame must be approved for
use in a fire rated door.