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a division of elemental LED
HOW TO READ AN LM-79 DISTRIBUTION REPORT
Polar Candela Distribution & Intensity Candlepower Summary
The Polar Candela Distribution graph (left) and Candlepower Summary (below) matrix portrays
luminous intensity, and is measured in candelas. It’s valuable for providing an understanding of the
shape and intensity of light that will emit from the LED tape light/luminaire.
Vertical Angle Candlepower at defined angle Total lumens for 5° zone
For example, according to this matrix (above), at a 25° vertical angle the Candlepower of this
luminaire is 38 candelas. Between the 20-25° angle the total light output is 9 lumens. This plot is
marked on the graph (left) by the green circle.
Zonal Lumens & Percentages
The Zonal Lumens & Percentages matrix (left) provides data of the luminaires’ Lumens and Total
Luminaire Output in a specific Vertical Zone. It is specifically used for determining qualifications for
Vertical Zone Lumens %Luminaire energy efficiency programs such as Energy Star, CEC Title 24, and Design Lights Consortium.
Example Image
90˚
80˚
70˚
60˚
50˚
Vertical Zone
Advertised valueAlong Luminaire
40˚
Data at defined zone
30˚
20˚
0˚ 10˚
In the Example Image (above) you can see the highlighted zone 0-40. According to the Zonal Lumens
& Percentages matrix (left) there are a total of 68 lumens in this zone and emits 36.05% of the total
luminaire's light output.
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Cone of Light Tabulation & Cone of Light Plot
0 Mounting Surface The Cone of Light matrix (far left) is
helpful for providing a representation
of max illuminance (footcandles) and
4 diameter of beam spread at different
distances away from the luminaire.
6 It’s useful for determining how far
Mounting Height (ft.)
away the fixture should be mounted
8
from the illuminated object.
10
Diameter (ft.) For example, if the luminaire is
H N D 12 mounted at 8 ft., the diameter of
the beam spread is 9.84 ft., which
14
Nadir (0°) produces 0.664 footcandles at nadir.
16
Spacing Criterion (SC)
Spacing Criterion indicates how far apart luminaires can be spaced while providing acceptable
uniformity of illuminance to the working plane (surface).
Luminaire Spacing = SC (Along) x Mounting Height
In relation to
Mounting Height
In relation to 0°-180° In relation to 90°-270°
Horizontal Horizontal
Luminaire Spacing = SC (Across) x Mounting Height
In relation to
Mounting Height
In relation to 0°-180° In relation to 90°-270°
Horizontal Horizontal
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®
a division of elemental LED
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Specifications are subject to change without notice.
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HOW TO READ AN LM-79 REPORT | SS082317-1.0 | 2 OF 2
