LABORATORY
LIGHTNING SYSTEM
Incorporation of large windows in
laboratory buildings provides sufficient brightening or illumination for most
of the work done in the day.
However natural light in the laboratory
should be supplemented with artificial electrical lightening system used in the
lab is either incandescent (lamp with heated filament) or discharged source
i.e. electric lamp using gas. Nevertheless, incandescent type is now been
replaced entirely by florescent discharged tubes. Adequate illumination is
necessary for the following reasons:
1. To
prevent severe eye strain.
2. To
prevent damage to the eye.
3. To
enable us view slides correctly.
4. To
help us make it possible and easy to read fine graduation on equipment thereby,
preventing errors and accident.
LIGTNING
EFFICIENCY
The amount
of illumination resulting from a particular lightning design depends on a
number of factors:
1. Illumination
power of the source
2. Efficiency
of the fitting
3. Distribution
of light from the fitting
4. Depreciation
from the lamp
5. Size
of the laboratory
6. Colour
of ceilings, walls and furnishing
7. Height
of the fitting
DEPRECIATION
IN ILLUMINATION
To
avoid depreciation in light output, the choice and placing and fitting must
allow adequate facilities for cleaning and servicing. The amount of
depreciation of the initial illumination due to the lack of maintenance and
other contributory factors is perhaps not generally realized. Lightning expert
usually allow a depreciation of 30% in estimating lightning requirement but
depreciation of up to 50% may occur, through neglect. Such depreciation may be
due to:
1. Aging
of a lamp
2. Dirty
fittings
3. Variation
between recommended and actual voltage
However, a routine inspection by a qualified person
at intervals not exceeding 4 months is to be recommended and for full
efficiency, walls and ceiling must be regularly cleaned or redecorated.
DIRECT
LIGHTNING
It is
used in the circumstances where good light is required at the work place. In general,
it tends to produce shadows and a dark ceiling effect. This effect may be
minimized by selecting furniture and floors with the deflectance value.
INDIRECT
LIGHTNING
With
indirect lightning, little shadow effect is experienced but colour and
non-glave ceilings and upper side walls are essential. It is recommended for
office use and for exerting visual tasks. A combination of direct and indirect
lightning is excellent.
DIFFUSED
LIGHTNING
Shadows
may be avoided by using diffuse lightning and an even illumination. This tends
to produce glare and for this reason it is not recommended for a visual task
and prolong high wall. Walls and ceilings must have a deflectance value.