IM 51011-01EN
52
21. Illuminance Measurement Method
(Extract from the JIS C 7612 standard)
For general lighting, illuminance of a horizontal surface is typically
measured and averaged.
Unless otherwise specified, the height of the measured surface
shall be within 85 cm from the floor, 40 cm from the tatami floor
in the case of a Japanese-style room, or the surface of the floor
or ground in the case of a corridor or in outdoors (if it is difficult to
measure the illuminance on the floor or ground, the height shall be
within 15 cm from the floor or ground).
The location for measurement shall be divided into equal areas
by vertical and horizontal partitioning lines, and the average
illuminance for each area shall be calculated. The calculated
average of the areas shall be the average illuminance of the total
area measured.
There are two methods to determine the average illuminance for
each area: the 5-point method and 4-point method.
(JIS: Japanese Industrial Standards)
5-point method
The middle of each side (the
m
point) and the center of gravity
(the
g
point) shall be measured to obtain illuminances Em and
Eg, and then the average illuminance for each area shall be
determined according to the following expression:
E
0
= (Em
1
+Em
2
+Em
3
+Em
4
+2Eg) = (∑Em+2Eg)
1
6
1
6
m4
m3
m2
m1
g
Summary of Contents for 51011
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