General Order 64
Section IX
Detail Construction Requirements For Signal Lines – Class “S” Circuits
95 Strain Insulators.
(a) Use and Location: Where signal lines and supply lines occupy joint facilities, guys for signal line construction shall be equipped with insulators located as given in Rule 66 for supply lines of 17,000 volts or less. This shall likewise apply where signal lines, cross or are in conflict with supply lines, provided said guys are not less than 6 feet horizontally from any supply line or are at least 8 feet below the nearest supply conductor. Only the facilities installed last in point of time shall be held in violation of the above.
(b) Construction: Strain insulators shall preferably be of the interlocking type, and shall have mechanical strength at least equal to that of the guys in which they are installed.