IEC 62783-2:2025

Overview

IEC 62783-2:2025 - Twinax cables for digital communications, Part 2 - is a family specification that defines requirements for indoor twin-axial (twinax) cables used with Ethernet-over-twinax physical interfaces. This second edition (2025) replaces the 2019 edition and aligns the family specification with the updated generic twinax requirements in IEC 62783-1:2023 and the latest twinax link-segment PHYs added to ISO/IEC/IEEE 8802-3 (IEEE 802.3). The standard covers both a single twinax element and multiple elements within the same sheath and is intended to support IEEE/ISO/IEC Ethernet PHYs such as short‑reach implementations (e.g., 10GBASE-CX, 25G/50G/100G CR variants).

Key topics and technical requirements

IEC 62783-2:2025 specifies definitions, construction rules and extensive test requirements, including:

• Cable construction and identification
  • Conductor, insulation, colour coding, drain wire, screening, sheath, and element make‑up for twinax cable assemblies.
• Electrical tests
  • Conductor resistance, resistance unbalance, dielectric strength, insulation resistance, mutual capacitance, surface transfer impedance and coupling attenuation.
• Transmission performance
  • Characteristic impedance, return loss, insertion loss/attenuation, propagation delay, inter- and intra-element delay (pair skew), NEXT, FEXT, ACR‑F, TCL, differential‑to‑common‑mode conversion (S_cd21), ELTCTL and screening attenuation.
• Mechanical and dimensional tests
  • Dimensional checks, tensile/elongation, crush, repeated bending, vibration and tensile performance of finished cables.
• Environmental and safety tests
  • Thermal ageing, cold bend/impact, damp heat, salt mist, flame propagation for single and bunched cables, smoke generation and halogen‑free compound verification.

Applications and who uses this standard

IEC 62783-2 is directly useful for:

• Cable designers and manufacturers specifying and producing twinax cable for short‑reach Ethernet interconnects.
• Test laboratories and conformity assessors performing electrical, mechanical and environmental qualification.
• System integrators and OEMs (servers, switches, storage arrays) selecting compliant twinax assemblies for rack‑level and in‑cabinet Ethernet links.
• Procurement and standards engineers ensuring components meet specified PHY link‑segment requirements.

Typical applications include high‑speed, short‑reach Ethernet links in data centers, server-to-switch interconnects and telecommunications equipment where compact, shielded twinax cables provide cost‑effective high throughput.

Related standards

• IEC 62783-1:2023 (generic twinax cable requirements)
• ISO/IEC/IEEE 8802-3 / IEEE Std 802.3 (Ethernet physical interfaces and twinax link‑segment PHYs)

Keywords: IEC 62783-2:2025, twinax cable, Ethernet-over-twinax, twin‑axial, Ethernet PHY, IEEE 802.3, indoor cables, transmission characteristics, cable testing.