Notification Appliances—E Series Speakers and Strobe Speakers 7
UL 1971 requires a polar light distribution pattern to enhance the likelihood of alerting
hearing impaired individuals throughout an area. Figure 2 illustrates the way the standard
measures light intensity, both horizontally and vertically. Tables 3 and 4 list the UL
minimum requirements and the actual value of the light intensity of the strobe signal.
Figure 2: Light Distribution Comparison
Light Distribution
lightdis.drw
Wall Mount Horizontal Light Distribution
Wall
L ight
9 0
4 5
0
-90
-4 5
Zero Axis
Wall
Floor
0
5
10
15
20
25
9 0 85 80 75 70 65 6 0 55 5 0
4 5
4 0
3 5
3 0
Wall Mount Vertical Light Distribution
D eg ree s
P erce n t
of R ated
L ig ht O u tp u t
1 0 0
9 0
6 5
4 8
3 4
2 7
2 2
1 8
1 6
1 5
1 3
1 2
1 2
1 2
0
5 -30
3 5
4 0
4 5
5 0
5 5
6 0
6 5
7 0
7 5
8 0
8 5
9 0
D eg ree s
P erce n t
of R ated
L ig ht O u tp u t
1 0 0
9 0
7 5
5 5
4 5
4 0
3 5
3 5
3 0
3 0
2 5
2 5
0
5-2 5
3 0 -45
5 0
5 5
6 0
6 5
7 0
7 5
8 0
8 5
9 0
