There are three main factors that greatly influence the magnitude
of maximum demand and the time of its occurrence. The most frequent
is the weather as it affects light intensity during daylight hours and
temperatures throughout the day and year.
The sharpest factor and perhaps
that of least duration is special events which result in a temporary
slowdown of activities or a greatly increased usage of lighting, radio,
and TV and associated increases in water pumping, cooking, and other
loads. The largest factor is changes in business conditions accompanied
by significant changes in industrial demands and consumption; while
much less significant, fluctuations in both residential and commercial
consumer demands also follow such changes in business conditions.
The nature, magnitude, and time of these fluctuations are generally
unpredictable. Some estimate of them can be gleaned, however, from
past experiences, which may vary widely in different areas of the country.
Provision for these fluctuations should be taken into account in the
planning of distribution systems.
