Figure 16.
Sections of the feeder line.
Figure 17.
Wire size tabulation.
h. Example
of
pole
size
into the soil.
This establishes the
determination. In order to connect an
total required length of the pole at
installation to an existing 20,000-
36.5 feet.
volt high tension line, a new line
9. SYSTEM DESIGN
must
be
run
3,500
feet
across
generally level soil.
No. 2/0 hard-
Perhaps the best way to illustrate
drawn bare copper wire will be used,
the application of all the steps
making seven 500-foot spans. Assuming
involved
in
the
design
of
an
the high-tension conductors are the
electrical distribution system is by
only ones to be strung, what is the
means of an example.
required height and length of pole?
Situation: As S3 of a construction
Solution: From table 2 the class of
group, you have been directed to
pole is a No. 5 with a minimum height
furnish adequate electric power to
of 30 feet.
From figure 12 the sag
that portion of a new installation for
under the above conditions will be
which
other
utilities
have
been
approximately 14 feet.
From figure
installed and completed. The building
10, using the specifications for an
layout is shown in figure 13.
No
area accessible to pedestrians only,
outside source of electricity exists.
the required clearance is 17 feet.
Figure 14 shows the connected lighting
From the above requirements the height
and power loads, the total demand, and
of pole above the ground should be 14
the type of service for each building
+ 17 = 31 feet. From table 4 the pole
shown in the layout.
From this data,
should be set a distance of 5.5 feet
the design of the system follows.
2-22
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