IEC 60794-1-107:2025

Overview

IEC 60794-1-107:2025 - "Optical fibre cables - Part 1‑107: Basic optical cable test procedures - Mechanical test methods - Torsion, method E7" is an IEC international standard that defines a uniform test method to evaluate the torsion performance of optical fibre cables. The procedure measures variation in fibre attenuation and checks for physical damage when a cable is subjected to mechanical twisting. This edition (2025) is a technical revision that replaces method E7 from IEC 60794‑1‑21:2015 and updates typical test lengths and the torsion apparatus loading arrangement.

Key topics and technical requirements

• Scope: Applies to optical fibre cables used with telecommunication equipment, including cables with combined optical and electrical conductors; the term “optical cable” covers fibre units and microduct fibre units.
• Objective: Measure change in attenuation and detect physical damage under torsional stress.
• Apparatus:
  • Two cable grips (one fixed, one rotatable) with adjustable separation.
  • Rotating clamp driven by torquing equipment (e.g., torquing lever).
  • Optional tensioning/loading weights to minimize sag and simulate installation conditions.
  • Optical attenuation measurement equipment per IEC 60793‑1‑46:2024 (change in attenuation by transmitted power).
• Procedure highlights:
  • Test length L is specified by cable type (see Table 1). Examples: outdoor stranded armored ≤ 10.0 m; most cables = 125 × diameter but with upper/lower limits per cable class.
  • One cycle = 180° clockwise → return → 180° counterclockwise → return; typically 10 cycles, each cycle completed within 1 minute (unless otherwise agreed).
  • Measure attenuation after clamping and in the first and last cycles at extreme positions held for ≥10 s.
  • Allow sample to rest ≥5 min before final measurements and visual inspection.
• Acceptance criteria: Defined by the relevant product/specification; typical failure modes: loss of optical continuity, increased fibre loss, and damage to sheath or core components.
• Information to specify/report: cable description, test length, applied tension, number of cycles, fibres monitored, maximum allowable attenuation change, rotating angle, cycle time, and test temperature.

Applications and users

• Primary users: cable manufacturers, independent test laboratories, telecommunications equipment vendors, procurement and QA teams, R&D and product development engineers.
• Practical uses:
  • Validate cable design against installation twisting and handling stresses.
  • Establish supplier/acceptance test criteria for contract specifications.
  • Investigate field failures related to torsional loads.

Related standards

• IEC 60794-1-2 - reference guide to test methods, general requirements and definitions.
• IEC 60793-1-46:2024 - method for monitoring changes in attenuation (used for optical measurements in E7).

Keywords: IEC 60794-1-107:2025, torsion method E7, optical fibre cables, torsion test, cable torsion, attenuation change, mechanical test methods.