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.
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Table 7: Size and Material of Tie Wires
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Line Conductor |
Tie Wire |
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Material |
Size |
Size |
Material |
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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 |
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2 AWG & larger |
4 AWG |
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Galvanized iron or galvanized steel |
10 BWG & smaller |
Same as line conductor |
Soft galvanized iron or galvanized steel |
|
9 BWG |
10 BWG |
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8 BWG |
9 BWG |
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4 & 6 BWG |
8 BWG |
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Aluminum or ACSR |
4 AWG & smaller |
Same as line conductor |
Soft aluminum or aluminum alloy |
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or 6 AWG |
Strong alloy aluminum* |
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2 AWG & larger |
4 AWG |
Soft aluminum or aluminum alloy |
|
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or 6 AWG |
Strong alloy aluminum* |
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* 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. |
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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
47.2
and 47.3
for conductor tensions up to 2,000 pounds per conductor.
Note: Revised March 9, 1988 by Resolution E–3076 and February 5, 2014 by Decision No. 14-02-015.
D. Replacements (See Rule 44.3 )