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SUGGESTED LIGHT
LEVELS: (footcandles)
Offices, Classrooms 30-100
Industrial High-bay 30-50
Manufacturing (on task) 30-150
Hallways, Corridors 5-10
Merchandising 30-150
Roadway 0.3-1
Baseball, home plate (PRO) 350
Indoor Parking 2-5
Outdoor Parking 0.5-2.0
Illumination is
measured in footcandles. One footcandle is the illumination one
foot from a standard candle; 30 foot-candles (abbreviated fc)
is thirty times higher.
A
typical light level for an indoor space is 30-50
fc.
The human eye
is very adaptable: full sunlight is about 8000 fc at noon; full
moonlight is only 0.01 fc (one hundredth of a foot-candle!). If
you reduce the light level people may adapt but there may be a
cost.
Lower
light levels can lead to poor morale, reduced
productivity, increased errors and so
on.
There has been speculation
that the human errors that caused nuclear problems at
Three-Mile Island and Chernobyl could have been avoided if the
light levels in the control room had been higher: workers would
have been more alert, even at 4:00 a.m. Talk about the cost of
poor lighting!
There are
intelligent ways of reducing energy costs (retrofit with newer
technologies) and there are "not-so-intelligent" ways of
reducing energy costs (simply remove one lamp from a 3-lamp
fixture).
What Does an "IP" Rating
Mean?
An "IP Code" which can usually be found in a brochure or user's
manual. The "IP Code" stands for "International Protection
Rating" or "Ingress Protection Rating" which classifies the
level of protection that electrical appliance
provide
against the intrusion of solid objects or dust,
accidental contact, and water. To be
clear it has NOTHING to do with how well a particular
device can withstand a drop or shock.
The code is expressed as IPXX with "X" being numbers. For
example, has an "IP" Rating of 55.
The first numerical digit indicates the level of protection
against solid particles such as dust, dirt or other
matter. The second numerical digit indicates the level of
protection from harmful ingress of water. The higher the values
of each number the higher the resistance to these contaminants.
With lower
values are more likely intended for use in offices,
schools, churches and similar "carpeted areas." With higher
numerical "IP" ratings are designed for use anywhere, but
especially in environments where dust and moisture could be
prevalent. You can use an "IP" number to determine if it's
built for the environment you intend to use it or store it in.
If you find that it has a letter "X" in its "IP" Rating, it
means a value has not been assigned for that type of ingress.
For example, you may find a product with an "IP" Rating of
"X4."
Here's the scale you can refer to:
First Number
Effective Against
0
No protection against contact
and ingress of objects
1
Any large surface of the body, such as the back of a
hand,
but no protection against deliberate contact with a body
part
2
Fingers or similar objects
3
Tools, thick wires, etc.
4
Most wires, screws, etc.
5
Dust protected--Ingress of dust is not entirely
prevented,
but it must not enter in sufficient quantity to interfere
with
the satisfactory operation of the
equipment
6 Dust
tight--No ingress of dust; complete protection
The second numerical digit indicates the level of protection
from harmful ingress of water: Second Number
Effective Against
0 Not
protected
1 Dripping
water
2 Dripping
water when tilted up to 15 degrees
3 Spraying
water
4 Splashing
water
5 Water
jets
6 Powerful
water jets
7
Immersion
up to 1 meter
8
Immersion
beyond 1 meter
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