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General Order 64-A

 

Section IV

 

Strength Requirements For All Classes Of Lines

 

49.1   Poles, Towers and Other Structures

 

A.    Strength

Wood poles shall be of sound timber, free from defects which would materially reduce their strength or durability and they shall have sufficient strength to withstand, with safety factors at least equal to those specified in Rule 44, the maximum stresses to which they are subjected under the loading assumptions set forth in Rule 43.  Certain poles are subject to special stresses due to angles in the line, dead-ending of conductors or other attachments, which stresses must be included in computing the loading and safety factor.  Poles subject to these special stresses sometimes require the use of guys, in which case the pole below the point of guy attachment shall be considered merely as a strut, the guy taking all the lateral stresses.  In such cases the pole strength requirement shall apply at the point of guy attachment rather than at the ground line.  Spliced wood poles shall not be used in crossing or conflicts where Grade A or B construction is required.  The ultimate strength is given in Rule 48.

Steel and reinforced concrete poles, together with their foundations, shall be of such material and dimensions as will withstand the loads with safety factors at least equal to those specified in Rule 44.
  The materials for these poles shall conform to the requirements of Rule 48.2 and 48.3.  (For loadings and safety factors see Rules 43 and 44.)

 

B.    Dimensions and Settings

The nominal top diameter of poles shall not be less than the following:

 

Grade A heavy loading district 7 inches minimum top diameter

 

Grade A light loading district 6 inches minimum top diameter

 

Grades B and C heavy and light loading districts 6 inches minimum top diameter

 

Grade F heavy and light loading districts carrying four open wires or less 12 inches minimum perimeter; exceeding four open wires and for cable 15 inches minimum perimeter.

 

Note  Poles having a ground line circumference of less than 12 inches are not safe to climb unless supported by guys, pike Poles, etc.

 

The character of soil to a large extent determines the depth of pole setting and the following depths considered applicable for good firm soil.  Where the soil is not firm, special methods of pole setting must be resorted to.  Where poles are set subject to heavy strain, or at corners and curves, a greater depth should be used.  In rock the minimum depth shall be 3 feet.

 

 

For communication lines sawed of a cross-section of 36 square inches or less may be set to a depth of 6 inches less than the specifications shown in the following table:

 

Table 5

Pole Setting Depths

Total length of pole

feet

Depth in ground

feet

20

4

25

4.5

30

5

35

5

40

5.5

45

6

50

6.5

55

7

60

7

65

7.5

70

7.5

75

8

80

8

 

 

C.    Gains

On round wood poles gains shall be provided for cross arms.  The maximum depth shall not exceed on inch shall be of the same width at the cross arms.  Approved mechanical gains are permitted.

 

D.      Replacements:  (See Rule 44.2.)