IEC 61156

IEC 61156 Series – Symmetrical Pair/Quad Cables for Digital Communications

The IEC 61156 series defines the international standards for symmetrical pair and quad cables used in high-speed digital communications. These cables are essential components of structured cabling systems and support a range of data transmission applications, including local area networks (LANs), industrial automation, and data centres.

The series ensures consistency in electrical performance, mechanical construction, and environmental suitability. It provides manufacturers, installers, and system designers with the necessary framework for evaluating cable performance across different categories and use cases, particularly where high-frequency signal integrity and electromagnetic compatibility (EMC) are critical.

Structure of the IEC 61156 Series

The IEC 61156 series is divided into several key parts based on cable type, performance category, and application environment.

Part 1 – Generic Specification

Outlines general requirements, definitions, test methods, and construction rules for symmetrical pair and quad cables. It forms the basis for the other parts in the series.

Part 2 – Floor Wiring

Defines screened or unscreened pair/quad cables for horizontal floor wiring in digital communication systems. Not intended for low-impedance sources like mains power. Includes templates for detail specs (61156-2-1) and capability approval (61156-2-2).

Part 3 – Work Area Wiring

Specifies screened and unscreened pair/quad cables for work area wiring in digital communications. Not for use with low-impedance sources. Includes detail spec layout (61156-3-1) and capability approval (61156-3-2).

Part 4 – Riser Cabling

Defines screened or unscreened pair/quad cables for vertical (riser) installations, up to Category 5 (Class D). Includes detail spec layout (61156-4-1) and capability approval (61156-4-2).

Part 5 – High-Performance Horizontal Floor Wiring

Specifies screened or unscreened pair/quad cables for horizontal wiring, supporting data and low voltage remote powering (e.g. PoE). Transmission is specified at 20 °C. Includes capability approval (61156-5-2).

Part 7 – Digital and Analogue Systems:

Specifies four-pair S/FTP cables for digital and analogue applications, including video. Designed for systems using up to four pairs simultaneously. It defines a cable with four individually screened pairs (S/FTP) and an optional common screen over the core. Capability approval requirements are detailed in IEC 61156-7-2.

Part 8 – High-Frequency Work Area Cords:

Specifies four-pair S/FTP cables for work area cords up to 1 200 MHz, supporting high-speed data and DC remote powering. Optional common screen included. Not for mains power.

Part 9 – Fixed Cables for High-Speed Channels (up to 2 GHz):

Defines fixed cables (X/FTP, X/UTP, U/FTP) for high-speed channels up to 2 GHz. Includes Category 8.1 (Class I) and Category 8.2 (Class II) per ISO/IEC TR 11801-9901.

Part 10 – Work Area Cords for High-Speed Applications (up to 2 GHz):

Specifies X/FTP, X/UTP, and U/FTP cables for work area cords up to 2 GHz. Defines Category 8.1 (Class I) and Category 8.2 (Class II) per ISO/IEC TR 11801-9901.

Part 11 – Single Pair Cables (Types T1-C and T1-D):

Specifies screened or unscreened single-pair cables for office, home, and industrial applications such as 1000BASE-T1, operating up to 600 MHz (T1-C) or 1.25 GHz (T1-D). Intended for use in balanced communication systems in accordance with ISO/IEC 11801-1.

Part 12 – Single Pair Cables (Types T1-B and T1-C):

Defines single balanced pair cables for structured cabling systems, operating from 0.1 MHz up to 600 MHz (T1-B) or 1.25 GHz (T1-C). Suitable for office, home, and industrial use, including remote powering, based on ISO/IEC 11801-1:2017.

Part 13 – 10 Mbit/s Single Pair Cables (up to 1 km):

Covers cables supporting 10 Mbit/s transmission over single twisted pair for distances up to 1 km (A-1000) or 400 m (A-400). Operates up to 20 MHz, designed for screened or unscreened installations in industrial or building environments.

Part 14 – Work Area 10 Mbit/s Single Pair Cables (A-1000W / A-400W):

Specifies cables for work area connections transmitting 10 Mbit/s over single pairs up to 1 km, with types A-1000W and A-400W offering variants with/without attenuation de-rating. Operates up to 20 MHz and supports low voltage remote powering.

Part 15 – Circuit Integrity Cables During Fire (Based on Part 5):

Describes cables based on IEC 61156-5, designed to maintain circuit integrity and data transmission during and after fire exposure. Includes test methods and evaluation criteria for assessing fire performance and remote powering capability in ELV systems.