IEC 61935-1-2:2018

Overview

IEC 61935-1-2:2018 sets out additional standardized procedures for measuring resistance unbalance in installed balanced cabling, as specified within ISO/IEC 11801. Developed by the International Electrotechnical Commission (IEC), this standard defines the methods and field tester accuracy requirements necessary for using field test instrumentation to assess resistance unbalance, a key parameter in ensuring reliable information technology cabling performance.

The primary aim of IEC 61935-1-2:2018 is to supplement IEC 61935-1 by detailing specific measurement techniques and extending requirements related to resistance unbalance, both within a pair and between pairs. Consistent resistance balance helps to minimize signal degradation and electromagnetic interference, making this standard essential for installers, network engineers, and professionals involved with structured cabling systems.

Key Topics

• Measurement Procedures: Establishes precise reference measurement protocols for both within-pair and between-pair resistance unbalance, focusing on the practical application of DC resistance testing in the field.
• Field Tester Accuracy: Specifies the minimum accuracy, data resolution, and reporting standards for field test equipment used in cabling validation.
• Reporting Requirements: Defines the necessary data and summary information that must be reported by field testers, including pass/fail results, margin calculations, and worst-case conditions.
• Error Models: Details the error models for DC loop resistance and resistance unbalance, clarifying both constant error terms and those proportional to measured resistance.
• Compliance to ISO/IEC 11801: Ensures measurements and tolerances align with the generic cabling specifications outlined in ISO/IEC 11801-1, supporting global compatibility and performance.

Applications

IEC 61935-1-2:2018 is vital in the following practical scenarios:

• New Cabling Installations: Verifying that newly installed balanced cabling meets industry resistance unbalance requirements using field testers helps prevent network issues.
• Certification and Auditing: Used by certification bodies and auditors to confirm cabling systems' compliance with international performance standards such as ISO/IEC 11801.
• Troubleshooting and Maintenance: Field engineers rely on these guidelines to diagnose and address issues related to excessive resistance unbalance, which can cause slowdowns, errors, or connection failures in IT networks.
• Upgrades and Retrofitting: Ensuring legacy or upgraded cabling installations are within required resistance unbalance thresholds, especially when reusing existing infrastructure.
• Quality Assurance: Manufacturers and integrators use these standards as benchmarks for developing and testing cabling components and field test equipment.

By providing structured measurement procedures and accuracy requirements, IEC 61935-1-2:2018 helps maintain cabling reliability, minimize electromagnetic interference, and ensure robust data transmission in enterprise and commercial IT environments.

Related Standards

• IEC 61935-1: Specification for the testing of balanced and coaxial information technology cabling – Part 1: Installed balanced cabling as specified in ISO/IEC 11801 and related standards.
• ISO/IEC 11801-1: Information technology – Generic cabling for customer premises – Part 1: General requirements.
• IEC 61935 Series: Includes further parts relevant to testing methods and requirements for balanced and coaxial cabling systems.

Adhering to IEC 61935-1-2:2018 provides assurance that installed cabling can deliver the expected network performance and reliability, reducing risks related to signal degradation and electromagnetic compatibility in modern IT infrastructures. For professionals involved in structured cabling, this standard is an essential resource for maintaining best practices and compliance with international benchmarks.