How to lay optical cables using steel strands

Optical cables are typically suspended on steel messenger strands and secured using lashing wire, ensuring proper tension, sag, and environmental protection.

Materials and Tools

• Steel Messenger Strand: A stranded steel cable, usually carbon steel with zinc or zinc-aluminum coating for corrosion resistance, supports the weight of the fiber cable. Common diameters and strengths are selected based on span length and environmental conditions .
• Lashing Wire: Stainless steel wire (0.038"–0.045") is used to secure the fiber cable to the messenger strand. It is annealed for ductility and selected for strength and corrosion resistance .
• Lasher Tool: A specialized device used to wrap the lashing wire around the fiber cable and messenger strand.
• Cable Guide: A smooth-surfaced guide rod kept ahead of the lasher to prevent cable damage and ensure proper alignment .
• Clamps and Expansion Loops: Lashing clamps and loops accommodate thermal expansion and prevent stress on the cable .

Installation Steps

1. Route Preparation: Survey the pole line, clear obstacles, and ensure a straight path for the cable reel and lasher. Verify permits and pole readiness .
2. Messenger Strand Installation: Tension the steel strand between poles to withstand the cable weight and environmental loads (wind, ice, snow). Proper sag must be maintained to avoid overstressing the cable .
3. Cable Placement:
   • Moving Reel Method: The cable is raised and lashed in one operation while the reel moves along the route .
   • Stationary Reel Method: The cable is pulled beneath the strand using cable blocks, and lashing begins from the far end toward the reel .
4. Lashing the Cable:
   • Pull the lasher at a constant speed while maintaining slight downward tension.
   • Keep the cable guide approximately 4 feet ahead of the lasher to prevent wrapping or twisting .
   • Double lashing may be used in high-vibration areas for added stability .
5. Termination and Expansion: Secure the lashing wire with clamps and form expansion loops at poles to accommodate thermal expansion and prevent stress on the fiber .
6. Inspection and Testing: Check for proper tension, sag, and secure attachment. Ensure no sharp bends or crushing forces that could degrade optical performance .

Additional Considerations

• Corrosion Protection: Use zinc-aluminum coated strands in coastal or aggressive environments for long-term durability .
• Cable Types: Standard loose tube, ribbon, figure-eight, or ADSS cables may be used depending on span length and proximity to power lines .
• Slack Storage and Future Expansion: Plan for mid-span slack, drop cables, and potential future fiber additions .
• Safety: Follow OSHA regulations and company safety protocols during aerial installation . By following these steps and using the appropriate materials, optical cables can be safely and efficiently installed on steel messenger strands, providing a durable and flexible aerial fiber network.