Importance of lighting:
Humans depend on Light for all activities.
Light is a natural phenomenon, very vital for existence, which is taken for
granted. In fact, Life involves day night cycles beginning with sunrise and
ending with sunset. Pre-historic man had activities limited only to day time.
Artificial light enables extended activity period employing in a planned
optimized manner, minimizing the resources.
Vision is the most important sense accounting
for 80% information acquisition for humans. Information may be acquired through
sun/moon light (direct/ reflected) or by using artificial light (closest to
natural light). Before we go any further, it is worth looking at Teichmuller’s
definition for lighting. “We say the lighting is good, when our eyes can
clearly and pleasantly perceive the things around us”. Therefore Artificial
light should be Functional and pleasant both physiologically and
psychologically. This is often achieved employing multiple sources. It must be
borne in mind that the sources should be economic and energy efficient. As all
of us are aware, all sources today employ electrical energy.
Electrical energy is supplied as a.c.
(alternating current) or d.c. (direct current). Usually electric power supply
is a.c. in nature, either single phase or three phases. It must be borne that
close circuit is a must for current flow. As it is well known losses exist in
all electrical circuits or lines.