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Typical Installation Outline
Vertical Run
The vertical run of transmission line must be allowed to expand and contact. This
is accomplished by securing the top of the vertical run with the appropriate fixed
hangers and supporting the remaining line using spring hangers. Spring hangers for
the vertical line should be spaced 10 feet. The springs must be tensioned according
to supplied loading charts. It is essential the vertical line is vertical and free
to move in the hangers. When installing it is customary to start at the base of the
tower and work toward the top. The first hanger should be installed above the base
elbow according to the following chart.
Vertical Distance to First Hanger
| Line Size |
20 ft |
40 ft |
60 ft |
80 ft |
| 3-1/8" and 4-1/16" |
5 ft |
7 ft |
8 ft |
8 ft |
| 6-1/8" and Larger |
10 ft |
15 ft |
18 ft |
20 ft |
Horizontal Run
It is recommended the horizontal run of transmission line from the tower to
the transmitter building be a minimum distance to allow sufficient movement
due the expansion of the vertical line. For complex layouts that include a
change in direction and elevation, care must be exercised not to overstress
elbows.
Minimum Horizontal Run Length
| Line Size |
500 ft |
1000 ft |
1500 ft |
2000 ft |
| 3-1/8" and 4-1/16" |
20 ft |
40 ft |
50 ft |
60 ft |
| 6-1/8" and Larger |
40 ft |
60 ft |
70 ft |
80 ft |
The line should be secured at the building entrance using a horizontal anchor
plate and supported with 3 point suspension hangers. The horizontal run should
be protected from falling objects such as ice.
Pressurization
Transmission line must be sealed and charged with a dry gas. Pressurization
protects against moisture and increases the peak power capacity. If moisture
is present in a transmission line, there will be an increase of loss and a
decrease in the maximum operating voltage. It is essential to purge newly
installed or repaired transmission line before power is applied to the system.
The required line pressure and type of gas will depend upon desired operating
conditions. Pressurization above 30 lb./in.² is not recommended.
Flange Torgue Specifications
| Line Size |
Bolt Size |
Torque |
| 1-5/8" |
5/16" |
130 in lb |
| 3-1/8" |
3/8" |
210 in lb |
| 4-1/16" |
3/8" |
210 in lb |
| 6-1/8" |
3/8" |
210 in lb |
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