A power fiber optic cable suspension strand, or messenger strand, supports aerial fiber optic cables while protecting the optical fibers from mechanical stress and environmental damage.

Structure and Components

A typical suspension strand system includes:

• Messenger Strand (Suspension Strand): A strong, pre-formed strand, often made of aluminum or steel, that carries the weight of the fiber optic cable between poles or towers, providing structural support and tension relief .
• Suspension Clamps: These clamps secure the cable to the messenger strand and include components such as an aluminum alloy clamp plate, rubber clamping blocks, U-shaped or right-angle hanging rings, bolts, nuts, and grounding wires . The rubber blocks reduce compression and bending stresses on the cable.
• Mechanical Suspensions: Lightweight assemblies designed to support vertical, transverse, and longitudinal loads, as well as angle pulls, without damaging the cable strands or affecting optical fiber performance. Breakaway bolts ensure proper torque during installation .
• Structural Reinforcing Rods (SRR): Used in some suspension systems to reduce compression and bending stresses on optical fibers. SRRs are typically non-reusable, while other hardware components can be reused if in good condition .

Function and Application

Suspension strands are primarily used in overhead fiber optic installations to:

• Support the cable along straight or angled spans between poles or towers.
• Protect optical fibers from excessive tensile forces, bending, and environmental stress.
• Facilitate grounding and secure attachment to pole line hardware.
• Allow for safe installation and maintenance while minimizing the risk of fiber damage .

Installation Considerations

• Cable Bending Radius: Maintain a minimum bending radius of 15×D (no load) or 20×D (under load), where D is the cable diameter, to prevent fiber breakage .
• Tensile Load: Do not exceed the cable's maximum tensile strength during installation.
• Hardware Alignment: Ensure clamps, bolts, and hangers are properly aligned and torqued to avoid stress points.
• Slack and Splice Lengths: Include extra cable length for splicing and maintenance, as determined by the OSP engineer .

Summary

Power fiber optic cable suspension strands, combined with clamps and mechanical suspension hardware, provide a robust, reliable support system for aerial fiber optic cables. They ensure the optical fibers remain protected from mechanical stress, environmental exposure, and installation forces, while allowing for efficient and safe deployment along utility poles and transmission towers .