Safety of Fiber Optic Cable Steel Strand Construction

Fiber optic cables using steel strand construction are generally safe when properly designed, installed, and maintained, with attention to corrosion protection, mechanical tension, and grounding.

Mechanical Safety and Strength

Steel strands, often used as messenger or lashing wires in aerial fiber installations, provide structural support for the cable. These strands are typically made of stainless steel with diameters ranging from 0.038" to 0.045" and are annealed for high ductility, with minimum tensile strengths of 70–90 kpsi . Different stainless steel grades are selected based on environmental conditions: 430 for general use, 302 for corrosive environments, and 316 for severe conditions including chlorides and sulfides . Proper strand sizing ensures the cable can safely support its own weight and withstand environmental loads such as wind and ice.

Corrosion Protection

Corrosion is a critical factor in the long-term safety of steel strand construction. Zinc-aluminum coatings provide higher corrosion resistance than pure zinc, allowing strands to last decades in outdoor environments . Red rust, indicating complete coating failure, signals the need for higher corrosion protection. Regular inspection and selection of appropriate coatings based on local environmental conditions are essential to prevent premature failure.

Grounding and Electrical Safety

Although fiber optic cables do not carry electrical power, metallic components like steel strands can conduct electricity if they come into contact with live wires, lightning, or faulty electrical systems . Proper grounding and bonding according to NEC, ANSI, IEEE, and NFPA standards are required to safely dissipate unwanted currents, preventing electrical shock, fire, or equipment damage . Armored or hybrid cables with steel strands also provide mechanical protection and allow for traceability using metal detectors.

Installation Considerations

Safe installation requires adherence to tension limits, sag, and ground clearance requirements. The tension of the steel strand and the fiber under load must be calculated to avoid overstressing the cable . Minimum clearances, such as 18 feet above traveled roads and 40 inches from energized conductors, are standard to ensure public and worker safety . Planning tools like SAG10 or PLS-CADD can model these parameters for optimal safety . Coordination with local authorities and compliance with construction drawings and manufacturer guidelines are also critical .

Summary

Steel strand construction in fiber optic cables is safe when:

• Appropriate stainless steel grades and coatings are selected for environmental conditions.
• Mechanical tension and sag are properly calculated and monitored.
• Metallic components are correctly grounded and bonded.
• Installation follows industry standards, clearances, and local regulations. When these factors are addressed, steel strand fiber optic cables provide durable, reliable, and safe support for aerial and hybrid fiber networks .