Change List for this Rule

 

General Order 95

 

Section IV

 

Strength Requirements for All Classes of Lines

 

49.3        Pins and Conductor Fastenings

 

A.      Material

 

(1)       Pins: Insulator pins shall be of galvanized steel, galvanized iron or other corrosion–resisting metal or of locust or other suitable wood.
 

(2)       Fastenings:Conductor fastenings shall be of galvanized steel, galvanized iron or other corrosion–resisting metal.

 

B.      Size

 

(1)        Wood Pins:The minimum diameter of the shank shall not be less than 1–1/4 inches.

 

(2)        Metal Pins: The minimum diameter of the shank shall not be less than 1/2 inch.

 

(3)       Fastenings and Tie Wires: Fastenings and tie wires shall have no sharp edges at points of contact with conductors, and shall be applied in such a manner as not to damage the conductor. Materials and minimum sizes of tie wires for various sizes and types of conductors shall be as shown in Table 7 . Flat tie wire having a cross–sectional area not less than that of round wire of the gauge specified for tie wires may be used.

 

Table 7: Size and Material of Tie Wires

Line Conductor

Tie Wire

Material

Size

Size

Material

Copper, bronze, copper covered steel or composites of any of them

6 AWG & smaller 

Same as line conductor

Soft copper or annealed copper–covered steel

4 AWG

6  AWG

2 AWG & larger 

4 AWG

Galvanized iron or galvanized steel 

10 BWG & smaller

Same as line conductor

Soft galvanized iron or galvanized steel

9 BWG

10 BWG

8 BWG

9 BWG

4 & 6 BWG

8 BWG

Aluminum or ACSR

4 AWG & smaller

Same as line conductor

Soft aluminum or aluminum alloy

or 6 AWG

Strong alloy aluminum*

2 AWG & larger

4 AWG

Soft aluminum or aluminum alloy

or 6 AWG

Strong alloy aluminum*

 

*      Minimum tensile strength of 350 pounds

 

Note:      Revised July 22, 1968 by Decision No. 74342.

 

C.      Strength

Insulator pins and conductor fastenings shall be able to withstand the loads to which they may be subjected with safety factors at least equal to those specified in
Rule 44 .

 

Note:      A 1–1/2 inch by 9 inch locust pin will usually provide cantilever strength up to 1,000 pounds tension in the conductor with the conductor 3–1/2 inches above the crossarm and a safety factor of unity.

 

(1)       Longitudinal Loads Normally Balanced:

 

a)       Insulator Pins: Where longitudinal loads are normally balanced, insulator pins which support conductors shall have sufficient strength to withstand, with a safety factor of not less than unity, a load at the conductor position as follows:

 

Pins supporting supply conductors

700 pounds

Pins supporting Class C conductors

400 pounds

 

b)       Conductor Fastenings: Where longitudinal loads are normally balanced, tie wires or other conductor fastenings shall be installed in such a manner that they will securely hold the line conductor to the supporting insulators and will withstand without slipping of the conductor unbalanced pulls as follows:

 

Supply conductor fastening

40% of the maximum working tensions but not more than 500 pounds.

Class C conductor fastenings

15% of the maximum working tensions but not more than 300 pounds.

Tie wires are not required on Class C conductors at point– type transpositions in Grade F construction.

 

(2)       Longitudinal Loads Normally Unbalanced: At unbalanced corners and dead ends in Grades “A”, “B” or “C” construction, where conductor tension is held by cantilever strength of pin–type insulators and pins, double insulators and wood pins or single insulators and steel pins shall be used. Each line conductor shall be tied or fastened to both insulators, or the single insulator, to prevent slipping of the conductor under maximum working tension with a safety factor of 2 for the temperature and loading conditions specified in Rule 43 .

At changes in grade of construction and at end supports in Grades “A” or “B” construction where the conductors are not dead–ended and are supported on pin–type insulators, double insulators and pins with tie wires, or equivalent fastenings, will be considered as meeting the strength requirements of Rules
47.4 and 47.5 for conductor tensions up to 2,000 pounds per conductor.

 

Note:      Revised March 9, 1988 by Resolution E–3076.

 

D.      Replacements (See Rule 44.3 )