Original
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 ¼ inches.
(2) Metal Pins: The minimum diameter of the shank shall not be less than ½ inches.
(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. The materials and minimum sizes of tie wires for the 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 gage 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 composition of any of them |
6 AWG and smaller |
Same as line conductor |
Soft copper or annealed copper-covered steel |
| 4 AWG |
6 AWG |
||
| 2 AWG and larger |
4 AWG |
||
| Galvanized iron or galvanized steel |
10 BWG and smaller |
Same as line conductor |
Soft or galvanized iron or galvanized steel |
| 9 BWG |
10 BWG |
||
| 8 BWG |
9 BWG |
||
| 4 and 6 BWG |
8 BWG |
||
| Aluminum or ACSR |
4 AWG and smaller |
Same as line conductor |
Soft aluminum |
| 2 AWG and larger |
4 AWG |
||
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 ½ by 9 inch locust pin will usually provide cantilever strength up to 1000 pounds tension in conductor with the conductor 3 ½ 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 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 supporting insulators and will withstand without slipping of the conductors unbalanced pulls as follows:
Supply conductor fastenings |
|
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 the conductor tensions
are held by cantilever strength in pin-type insulators and pins, double pins and
insulators shall be used and each line conductor shall be tied or fastened to
both insulators so as to prevent slipping of the conductor under the maximum
working tensions with a safety factor of 2 under 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 wires, or equivalent fastenings, will be considered as meeting the
strength requirements of Rules 47.4 and 47.5 for conductor tensions up to 2000
pounds per conductor.
D. Replacements (see Rule 44.2)