IEC 60112:2020

Overview

IEC 60112:2020 - Method for the determination of the proof and the comparative tracking indices of solid insulating materials - is an IEC basic safety publication that specifies a laboratory test method to determine the Proof Tracking Index (PTI) and Comparative Tracking Index (CTI) of solid insulating materials using alternating voltage. The standard covers testing of samples taken from equipment parts and of plaques of material, includes a procedure for the determination of electrical erosion when required, and evaluates both material composition and surface condition. IEC 60112:2020 is intended primarily for use by technical committees preparing safety publications in line with IEC Guide 104.

Key topics and requirements

• Test principle: Alternating-voltage drop-wise application of a contaminant solution to a specimen surface to induce and detect tracking and erosion.
• Indices defined:
  • Proof Tracking Index (PTI) - acceptance/quality-control criterion.
  • Comparative Tracking Index (CTI) - numerical ranking for material comparison (based on 50-drop withstand and behaviour at 100 drops).
• Failure criteria: Tracking failure is indicated when an over-current device operates due to at least 0.5 A for 2 s across the test surface/specimen. Persistent flame and degree of erosion are included in pass/fail assessment.
• New in 2020 edition:
  • Introduction of Solution C (a contaminant with a surfactant) aligned with IEC 60587 methodology.
  • Solution B moved to Annex B for backward reference.
  • Introduction of a screening test to detect materials that fail at lower voltages despite withstanding high voltages.
• Scope limits: Test results are not directly suitable for determining safe creepage distances in apparatus design.

Applications and users

Who uses IEC 60112:2020:

• Materials manufacturers and quality-control laboratories for PTI/CTI verification.
• Product designers and component suppliers when selecting insulating materials for humid or contaminated-service environments.
• Test houses conducting comparative material ranking and erosion assessment.
• Standards and safety committees using PTI/CTI as input when drafting safety requirements.

Practical applications:

• Screening candidate insulating plastics, coatings and molded parts for tracking resistance.
• Supporting material selection and supplier quality control.
• Providing standardized test data for comparison between materials and formulations.

Related standards

• IEC 60587 - Inclined plane test for solids (more severe, outdoor-use assessment).
• IEC 60664-1 - Insulation coordination; clarifies creepage/clearance considerations.
• IEC Guide 104 and ISO/IEC Guide 51 - Guidance on basic safety publications and risk.
• Relevant ISO standards for specimen preparation (e.g., ISO 293, ISO 294 series).

Keywords: IEC 60112, proof tracking index, comparative tracking index, CTI, PTI, solid insulating materials, tracking, electrical erosion, alternating voltage, Solution C, screening test.