IEC 60794-1-129:2025

Overview

IEC 60794-1-129:2025 - "Optical fibre cables - Part 1-129: Basic optical cable test procedures - Mechanical test methods - Straight midspan access to optical elements, Method E29" specifies a uniform mechanical test for assessing whether optical elements (fibres, cords, ribbons, micro‑modules, etc.) can be removed from an optical cable by midspan access. The standard applies to optical fibre cables used with telecommunication equipment and hybrid cables containing both optical and electrical conductors. It updates and replaces the previous Method E29 (IEC 60794-1-21:2015 and its 2020 amendment), adding applicable cable type descriptions, revised figures, a displacement measurement description, and extended reporting requirements.

Key topics and technical requirements

• Test concept: Create two sheath windows (Window 1 and Window 2) separated by 6 m to access and withdraw cut optical elements through the cable midspan.
• Sample size: Recommended single sample ≥ 50 m, or two samples ≥ 20 m each.
• Windowing: Sheath windows nominally 80 mm long opened using manufacturer‑approved tools and methods to avoid damage or tight bends.
• Procedures:
  • Procedure 1: Cable routed with two controlled bends (≥ 4 core lay twists between bends; bends separated by ~3 m). Bend detail includes three mandrels (30 mm diameter) with specific depth/length features shown in the standard.
  • Procedure 2: Two immediately adjacent right‑angle bends applied between windows; bend radii must respect the cable’s minimum installation bend radius (agreed between manufacturer and user).
• Measurements and monitoring:
  • Monitor attenuation of non‑removed elements per IEC 60793-1-46 (Method A).
  • Optionally measure tensile force to extract an element (dynamometer).
  • Measure displacement (sliding) of non‑removed elements using marked longitudinal lines.
• Acceptance criteria (to be defined in the relevant specification) may include: no abrasion/perforation, no broken fibres, maximum allowable attenuation increase, maximum sliding distance, and maximum tensile force.

Applications and target users

• Cable manufacturers: Validate midspan accessability for designs intended to allow element withdrawal during installation or repair.
• Network operators and installers: Specify and verify cable types for field splicing, branching, and access procedures.
• Test labs and qualification teams: Perform standardized mechanical testing and generate reports to support product compliance and procurement specifications.

Related standards

• IEC 60794-1-2 - reference guide to test methods, general requirements and definitions.
• IEC 60793-1-46 - attenuation monitoring (Method A).
• IEC 60794-1-1 - generic specification - general.

This standard is essential where reliable straight midspan access is required to withdraw optical elements without damaging remaining fibres, and it provides the test procedures, measurement methods, and reporting details needed for consistent qualification and procurement.