LIGHTING EQUIPMENT
91
Variable Distributions.
A
fixture
which gives two or more desirable
light dis-
tributions of a different character will be credited with
the
maximum
distribution
is
Freedom from
points not obtainable where only one light supplied.
Glare.
The points to be accorded to a fixture under this heading are determined by a comparison test of the lighted fixture with a device known as a glare standard. This consists of five 6-inch crystal globes frosted on the inside and equipped with incandescent lamps, 10, 15, 25, 40 and 50 watts respectively, which represent a very definite scale of comfort or discomfort, and against which separately compared and rated as follows:
the fixture
is
TABLE X.
COMPARISON TEST VALUES FOR RATING FREEDOM FROM GLARE Fixture
Points
Matching
Allotted
10- watt globe
40
15- watt globe
40 38 30 20
25-watt globe 40-watt globe 50-watt globe
Fixtures more uncomfortable to view than the globe containing the 50-watt lamp are rejected.
Mechanical and Electrical Construction. Fixtures should attain reasonable excellence in mechanical
and
electrical
construction to assure safety and
continuity of service without incurring needless increase in cost. Reference to the National Electrical Code may
be
made
rial,
mateand workmanship, wiring, operating temperature. for guidance in judging electrical safety,