IEC 60793-1-40:2019

Overview - IEC 60793-1-40:2019

IEC 60793-1-40:2019 is the International Electrotechnical Commission standard that defines uniform measurement methods for attenuation of optical fibre. It provides agreed procedures and reporting requirements to support commercial inspection, quality control and acceptance testing of fibres and short cables. The standard describes four distinct attenuation measurement methods (A–D) and contains common requirements (Clauses 1–11) plus method‑specific requirements in Annexes A–D.

Key topics and requirements

• Scope and applicability

  • Covers procedures for measuring the attenuation of optical fibre to enable consistent commercial inspection.
  • Methods A–C apply to both class A multimode fibres and class B single‑mode fibres.
  • Method D (modelling spectral attenuation) is applicable only to class B fibres (single‑mode).

• Four measurement methods

  • Method A - Cut‑back: reference test method for accurate loss-per-length determination.
  • Method B - Insertion loss: practical method measuring loss through assemblies or connectors.
  • Method C - Backscattering: uses optical time‑domain reflectometry (OTDR) techniques to measure attenuation and to locate, quantify and characterize point discontinuities.
  • Method D - Modelling spectral attenuation: spectral modelling for single‑mode fibres to derive wavelength‑dependent attenuation.

• Common technical content

  • Calibration requirements, apparatus descriptions, specimen sampling, procedural steps, calculations and reporting of results.
  • Method‑specific appendices provide detailed apparatus setups, launch conditions, calibration and example traces or results.

• Notable updates in the 2019 edition

  • Improved measurement details for B6 fibre.
  • Enhanced calibration requirements for A4 fibre.
  • New Annex E with examples of short cable test results on A1 multimode fibres.

Practical applications

• Manufacturers use the standard for production quality control and to specify fibre attenuation performance.
• Test laboratories and certification bodies adopt these methods to provide reproducible, traceable attenuation data.
• Network engineers and installers use Method B and C for acceptance testing of assemblies and for troubleshooting (OTDR backscatter to locate faults).
• Product procurement and commercial inspection rely on standardized attenuation results to compare offers and verify contractual specifications.
• The standard supports consistent reporting of attenuation coefficients, spectral loss, connector/splice loss and discontinuity characterization.

Related standards

• IEC 60793 series (other parts covering optical‑fibre categories and characteristics) and documents from IEC TC 86 (Fibre optics) define fibre classes, terms and complementary test procedures. Users should consult the relevant parts of the IEC 60793 family for fibre definitions referenced by this part.

Keywords: measuring the attenuation of optical fibre, cut‑back, insertion loss, backscattering, modelling spectral attenuation, OTDR, optical fibre attenuation measurement.