The composite fiber optic overhead ground wire shall be made up of buffered flexible glass optical telecommunications fibers contained in a protective central fiber optic unit surrounded by concentric-lay stranded metallic wires in single or multiple layers.
The dual purpose of the composite cable is to provide the electrical and physical characteristics of conventional overhead ground wire while providing the optical transmission properties of optical fiber.
Stranded metallic wires
a) The basic construction shall have bare concentric-lay stranded metallic wires with the outer layer having left hand lay unless otherwise specified by the purchaser.
b) The stranded wires may be of multiple layers with a combination of various metallic wires within each layer. The direction of lay shall be reversed in successive layers.
c) The wires shall be so stranded that when the complete OPGW is cut, the individual wires can be readily regrouped and then held in place by one hand.
d) The preferred length of lay of the various layers of wires is 13.5 times the outside diameter of that layer, but the length of lay shall not be less than 10 nor more than 16 times this diameter.
e) The rated breaking strength of the completed OPGW shall be taken as 90% of the sum of the rated breaking strengths of the individual wires, calculated from their nominal diameter and the appropriate specified minimum tensile strength.
f) At the manufacturer's option, the rated breaking strength may include the strength of the optical unit. In this case, the manufacturer shall notify the customer if the fiber optic unit is considered a load bearing tension member when determining the total rated breaking strength of the composite conductor.
g) The finished wires shall contain no joints or splices unless otherwise agreed upon between the manufacturer and the purchaser.
h) Hybrid designs not included in items a)-f) are not excluded from this standard.