December 2025: New Metrology Standards Boost Measurement Precision

A significant wave of metrology and measurement standards has been published in December 2025, enhancing global consistency and boosting confidence in measurement-based decision making. This part of our ongoing coverage examines five critical new and revised standards tackling uncertainty evaluation in instrument transformer testing, advanced methodologies for thermal ageing of electrical insulators, and comprehensive approaches to determining detection thresholds and limits for ionizing radiation measurements. These updates aim to raise the bar for accuracy, reliability, and compliance across sectors that depend on rigorous measurement, from electrical engineering to radiological protection.

Overview

Metrology—the science of measurement—forms the backbone of industrial quality assurance, safety compliance, and technological development. International standards in measurement and physical phenomena ensure that data is consistent, traceable, and trustworthy worldwide. For engineers, compliance officers, researchers, and procurement specialists, staying abreast of new specifications and requirements is essential to maintaining competitive, compliant, and future-proof operations.

In this article, you will learn:

• What the latest standards require and how they improve existing frameworks
• Key technical highlights and differences from previous editions
• Implementation impacts, compliance deadlines, and best practices
• Direct access to official documentation on iTeh Standards

Detailed Standards Coverage

IEC/IEEE 61869-21:2025 - Uncertainty Evaluation in Instrument Transformer Accuracy Tests

Instrument transformers – Part 21: Uncertainty evaluation in the accuracy test of instrument transformers

This foundational standard delivers requirements, methods, and best-practice guidelines for the comprehensive evaluation of uncertainty during accuracy testing of instrument transformers (ITs). Covering analogue and digital signals across a frequency range of 15 Hz to 400 Hz, it applies to both inductive and non-inductive transformer technologies. Its scope extends to laboratory and on-site accuracy testing, focusing on the identification and quantification of all sources of measurement uncertainty—ranging from reference standards, comparators, burdens, to the power source, and even environmental or setup-specific factors.

Key requirements include:

• Systematic determination and combination of uncertainty sources
• Evaluation and documentation of uncertainty contributions in calibration and on-site verification
• Application of both analog and digital measurement principles
• Prescriptive procedures for Type A (statistical) and Type B (analytical) evaluations of uncertainty

Intended for organizations involved in power and energy metrology, testing laboratories, manufacturers, and utilities, this standard’s implementation ensures better risk management in metrological verification and ultimately greater trust in transformer-based measurements.

Notable changes address recent advances in uncertainty modeling for digital measurement paths and set unified procedural requirements for on-site testing.

Key highlights:

• Covers both inductive and non-inductive instrument transformers
• Applies uniform uncertainty evaluation methods to laboratory and field settings
• Defines intervals and strategies for periodic accuracy verification

Access the full standard:View IEC/IEEE 61869-21:2025 on iTeh Standards

IEC 60216-1:2025 - Ageing Procedures and Evaluation for Electrical Insulating Materials

Electrical insulating materials – Thermal endurance properties – Part 1: Ageing procedures and evaluation of test results

IEC 60216-1:2025 establishes the overarching framework for accelerated thermal aging of electrical insulating materials. It details standardized experimental procedures, specimen preparation, property selection, exposure temperature and time, and environmental controls. The main purpose is to derive thermal endurance characteristics, such as Temperature Index (TI) and Thermal Endurance Profile (TEP), enabling manufacturers and quality engineers to predict the lifespan and reliability of insulating systems under elevated thermal stress.

Key specifications include:

• Statistically robust procedures for test planning, including material selection (with new guidance on color variants)
• Protocols for destructive, non-destructive, and proof tests
• Analysis methodologies including regression and statistical analysis for complete and censored data
• Updated criteria for thickness sensitivity and end-point selection
• Introduction of new, clarified definitions for TI and related properties
• Comprehensive requirements for environmental conditioning and reporting

This standard is pivotal for manufacturers, testing labs, procurement specialists sourcing insulation materials for electrical and electronic equipment, and anyone evaluating long-term material reliability.

Changes in this edition:

• Enhanced precision in the definition and use of Temperature Index (TI)
• Guidance on multi-color material evaluation
• Inclusion of statistical thickness sensitivity tests

Key highlights:

• Statistically justified test and analysis protocols
• Updated treatment for material color and thickness variability
• Unified reporting and documentation requirements

Access the full standard:View IEC 60216-1:2025 on iTeh Standards

ISO 11929-1:2025 - Characteristic Limits for Measurements of Ionizing Radiation: Elementary Applications

Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation – Fundamentals and application – Part 1: Elementary applications

ISO 11929-1:2025 is a cornerstone for quantifying and communicating measurement uncertainty, detection limits, and decision thresholds in ionizing radiation measurement tasks using counting methods. The standard lays out procedures rooted in Bayesian statistics and modern uncertainty principles (ISO/IEC Guide 98-3) for evaluating the trustworthiness of measured results, supporting regulatory compliance, and ensuring safety across nuclear facilities, analytical labs, and radiological protection programs.

Key requirements and guidance:

• Calculation of decision thresholds and detection limits for non-negative measurands
• Modeling the effects of background, calibration, and sample preparation on result uncertainty
• Procedures for deriving best estimates, coverage intervals, and their use in pass/fail decisions
• Applicability to a wide spectrum of counting measurement scenarios, with detailed annexes for handling repeated measurements and analogue ratemeters

It’s indispensable for organizations measuring environmental, workplace, or laboratory radioactivity and for those responsible for compliance with national/international radiation limits.

This edition addresses corrections in formula references, clarifies uncertainty propagation, and integrates user feedback for practical application.

Key highlights:

• Standardized framework for detection and decision limits
• Incorporates Bayesian statistics and state-of-the-art uncertainty analysis
• Broad application across ionizing radiation measurement activities

Access the full standard:View ISO 11929-1:2025 on iTeh Standards

ISO 11929-2:2025 - Characteristic Limits for Measurements of Ionizing Radiation: Advanced Applications

Determination of the characteristic limits (decision threshold, detection limit and limits of the coverage interval) for measurements of ionizing radiation – Fundamentals and application – Part 2: Advanced applications

As the companion to ISO 11929-1, Part 2 addresses increasingly complex measurement tasks—such as low-count-rate scenarios and those requiring advanced statistical treatment—by leveraging the Monte Carlo method and GUM Supplement 1 guidance for uncertainty evaluation. It provides practical schemas for propagating probability distributions of uncertainty, enabling deeper assessment of detection limits and confidence intervals where conventional statistics cannot adequately model uncertainties.

Highlights for implementers:

• Comprehensive procedures for incorporating systematic effects and complex uncertainty sources via Monte Carlo simulation
• Improved documentation and reporting flows for advanced use cases
• Guidance for dealing with low sample counts and non-linear effects
• Explicit methodologies for multi-source and multi-parameter measurement setups

Professionals utilizing high-stakes or scientifically advanced radiation measurement methods will find these requirements essential for robust compliance and credible reporting.

This revision addresses corrections to clauses, formulas, and definitions—ensuring clear interpretation and correct statistical treatment in emerging technical scenarios.

Key highlights:

• Extends coverage from elementary to advanced applications
• Enables the use of modern computational uncertainty propagation
• Prepares organizations for compliance with the most sophisticated regulatory and scientific frameworks

Access the full standard:View ISO 11929-2:2025 on iTeh Standards

Industry Impact & Compliance

The publication of these standards sends a clear signal to all measurement-driven industries: risk reduction, quality assurance, and regulatory compliance will increasingly rely on mastery of uncertainty management, validated test procedures, and sophisticated statistical methods. Organizations across power utilities, testing laboratories, nuclear facilities, and advanced manufacturing must review their internal procedures, train relevant personnel, and update equipment or analytical software to reflect new best practices.

Compliance considerations:

• Timely adoption is recommended to ensure conformity with international procurement, regulatory, or contractual obligations
• Internal guidance, calibration, and quality management systems should be updated accordingly
• Documentation and reporting flows may require revision to ensure traceable, auditable compliance

Benefits:

• Improved measurement reliability and reduced operational risk
• Greater global trust and interoperability among test results, certifications, and reports
• Enhanced capacity to meet customer, regulatory, and accreditation requirements

Potential risks of non-compliance:

• Increased likelihood of non-conformities and failed audits
• Exposure to regulatory fines or business interruptions
• Loss of market credibility

Technical Insights

Common Technical Requirements

• Rigorous uncertainty evaluation: All five standards emphasize a systematic approach to identifying, quantifying, and combining uncertainties—whether in electrical or radiological measurements
• Statistical and probabilistic rigor: Implementation of Bayesian and Monte Carlo techniques ensures accurate modeling, especially in advanced applications
• Robust documentation: Clear requirements for reporting measurement procedures, source data, and calculations

Implementation Best Practices

1. Conduct a gap analysis between current practices and new standard requirements
2. Train laboratory and quality personnel in latest statistical and uncertainty evaluation techniques
3. Update internal documentation, calibration procedures, and reporting templates
4. Validate or recalibrate measurement equipment as per new protocols
5. Engage with accredited bodies for third-party verification where required

Testing and Certification Considerations

• Ensure traceability of measurements to recognized standards
• Employ certified reference materials and participate in proficiency testing where applicable
• Document uncertainty budgets and verification intervals for all test setups and reporting

Conclusion / Next Steps

These December 2025 updates underscore the ongoing evolution in metrology and measurement science. Professionals, managers, and operators should prioritize reviewing these standards, updating procedures, and leveraging the linked resources below for full documentation. Doing so not only ensures compliance and market acceptance but also drives innovation and operational excellence.

Recommended actions:

• Download the latest standards from iTeh Standards
• Host internal information sessions or training on new requirements
• Subscribe to updates and alerts for further parts in this vital standards series

Stay at the forefront of measurement science—visit iTeh Standards for the latest publications, guidance, and tools.