Standards for the Laying of Mobile Optical Cables in Ducts

The installation of mobile optical cables in ducts should follow ITU-T L.100 and IEC TR 62691 standards, which define cable characteristics, mechanical limits, and recommended installation practices.

Key Standards

ITU-T L.100 (2024) specifies the characteristics, construction, test methods, and performance criteria for optical fiber cables installed in ducts and tunnels. It outlines the required mechanical and optical properties, including tensile strength, bend tolerance, and environmental resistance. The standard references IEC 60794-3-11 for outdoor duct, direct-buried, and lashed aerial applications, with additional requirements for duct and tunnel installations. It also includes electrical continuity tests for metallic elements and emphasizes that installation conditions should be agreed upon between the customer and manufacturer . IEC TR 62691 (2016) provides guidelines for handling and installing optical fiber cables in metropolitan communication networks, including underground ducts, trenchless techniques, microduct blowing, and direct burial. It covers special situations such as tunneling, lead-in installations, bridges, underwater, sanitary sewers, high-pressure gas pipes, and drinking water pipes. The report emphasizes that improper installation can degrade cable performance and provides recommendations to maintain optical integrity and mechanical safety .

Installation Guidelines

Mechanical Limits and Handling:

• Maximum pulling tension varies by cable type; for example, stranded loose tube and ribbon cables typically allow up to 600 lbf (2,700 N) during installation .
• Minimum bend radius should be observed both during installation (“loaded”) and after installation (“installed”). A general guideline is 15 times the cable outer diameter for working bend radius .
• Use figure-eight coiling for unreeled cable to prevent kinking or twisting, with loops typically 5–8 ft (1.5–2.4 m) in diameter . Duct Preparation and Safety:
• Ensure ducts are clean, free of sharp edges, and properly lubricated if required.
• Barricade areas where cable is unreeled to prevent pedestrian or vehicular interference .
• Pulling wheels or rollers should have a diameter at least twice the minimum working bend radius to avoid cable damage . Environmental Considerations:
• Cables must meet environmental resistance requirements for temperature, moisture, and chemical exposure as specified in ITU-T L.100.
• Special attention is required for installations in tunnels, sanitary sewers, or high-pressure pipes, as detailed in IEC TR 62691 . Documentation and Compliance:
• Maintain records of cable type, installation tension, bend radius, and environmental conditions.
• Follow manufacturer specifications and coordinate with network operators to ensure compliance with both ITU-T and IEC recommendations . By adhering to these standards, optical fiber cables can achieve optimal performance, longevity, and safety during duct installations.