What type of flame retardant should be added to optical fiber cables

LSZH (Low Smoke Zero Halogen) and OFNR/OFNP-rated jackets are the primary flame-retardant options for optical fiber cables, chosen based on installation environment and fire safety requirements.

Key Flame-Retardant Options

LSZH (Low Smoke Zero Halogen): LSZH jackets are made from halogen-free thermoplastic or thermoset compounds that provide excellent fire protection while producing minimal smoke and non-toxic gases during combustion . These cables are ideal for enclosed spaces, data centers, and areas with poor ventilation, where reducing smoke and toxicity is critical for personnel safety and equipment protection . LSZH materials also resist corrosion caused by acidic gases released in a fire . OFNR (Optical Fiber Non-Conductive Riser): OFNR cables are designed for vertical riser shafts and floor-to-floor installations. They meet UL-1666 standards and are self-extinguishing within 5 meters of flame spread . OFNR jackets provide sufficient flame resistance for multi-floor buildings where the risk of large-scale fire is moderate, but they may produce more smoke than LSZH in a fire . OFNP (Optical Fiber Non-Conductive Plenum): OFNP cables have the highest flame-retardant rating and are suitable for plenum spaces (air-handling areas). They are designed to self-extinguish quickly and emit minimal smoke and toxic gases, making them the safest choice for areas with high air circulation and strict fire codes . OFNP jackets are often used in data centers, commercial buildings, and critical infrastructure.

Selection Guidelines

• Installation Environment: Use OFNP for plenum spaces, OFNR for vertical risers, and LSZH for general-purpose or enclosed areas where smoke and toxicity must be minimized .
• Regulatory Compliance: Ensure the cable meets relevant standards such as UL-1666, IEC 60332, IEC 60754, or equivalent local codes .
• Safety Considerations: LSZH is preferred in areas with high human occupancy or sensitive equipment due to its low smoke and halogen-free properties .

Conclusion

For optical fiber cables, LSZH jackets are recommended for general indoor and enclosed spaces, while OFNR and OFNP ratings are chosen based on vertical riser or plenum installation requirements. Always verify the cable's fire rating with certified test reports to ensure compliance with local fire safety regulations .