The effective intensities are based on providing at least
0.405 lumens/m2 at the middle of the bottom edge of the
coverage area, 0.246 lumens/m2 at the bottom of the corners,
and 0.243 lumens/m2 at a height of 1.5 m in the corners
by a visual alarm device with the minimum distribution of effective
intensities of ANSI/UL 1971, Standard for Signaling Devices
for the Hearing Impaired of the United States.