IEC 60794-2-31:2019

Overview

IEC 60794-2-31:2019 specifies detailed requirements for optical fibre ribbon cables intended for indoor premises cabling. It supplements the family specification IEC 60794-2-30 and ensures compatibility with the ISO/IEC 11801 series (generic cabling for customer premises). The third edition (2019) with Amendment 1 (2020) introduces technical updates including the incorporation of OM5 and OS1a cabled fibre categories and retains OM1/OM2/OS1 for information only.

Key topics and technical requirements

• Scope and applicability: detailed specification for ribbon-style indoor optical fibre cables used in premises cabling (offices, data centres, homes, industrial premises).
• Fibre types and performance codes: supports OM3, OM4, OM5 (multimode) and OS1a, OS2 (single-mode) cabled fibre codes to align with ISO/IEC 11801.
• Attenuation limits:
  • Multimode (OM3/OM4/OM5): maximum 3.0 dB/km @ 850 nm and 1.5 dB/km @ 1 300 nm.
  • Single‑mode: OS1a - max 1.0 dB/km (at 1 310, 1 383, 1 550 nm); OS2 - max 0.4 dB/km (same wavelengths listed).
• Bandwidth (multimode): minimum multimode bandwidth values are defined in terms of overfilled launch and effective modal bandwidth at wavelengths including 850 nm, 953 nm and 1 300 nm. Example values for OM5 are given in the standard (e.g., multi‑wavelength overfilled and effective modal bandwidth entries). Guidance for effective modal bandwidth at 953 nm is provided for OM3 (1 033 MHz·km) and OM4 (1 459 MHz·km).
• Environmental and testing:
  • Fibre selection for cable testing per IEC 60794-1-1:2015, Annex B.
  • Temperature cycling per IEC 60794-2-10:2011 using MICE temperature ranges; tests performed on 50 m specimens with no allowed attenuation changes per IEC 60794-1-1.
• Relationship to family and product standards: this part relies on IEC 60793 product specifications for optical fibres and IEC 60794-2-30 family rules for ribbon cables.

Practical applications and users

Who uses this standard:

• Cable manufacturers specifying ribbon cable construction and performance
• System designers and integrators planning premises cabling (offices, data centres, multi‑tenant buildings)
• Procurement/specification writers who must ensure ISO/IEC 11801 compatibility
• Test labs and QA teams verifying attenuation, bandwidth and environmental performance

Why it matters:

• Ensures consistent, interoperable indoor ribbon cable performance across suppliers
• Helps select appropriate fibre class (OM3/OM4/OM5, OS1a/OS2) for application bandwidth and reach
• Provides repeatable test methods and environmental criteria for reliable in‑building networks

Related standards

• IEC 60794-2-30 (family specification for ribbon cables)
• IEC 60794-1-1 (generic specification - general)
• IEC 60793-2-10 (multimode fibre product specs)
• IEC 60793-2-50 (single-mode fibre product specs)
• ISO/IEC 11801 (generic cabling for customer premises - Parts 1–6)

Keywords: optical fibre ribbon cables, IEC 60794-2-31:2019, OM5, OS1a, premises cabling, multimode bandwidth, cabled fibre attenuation.