CTI and PTI describe a particular insulation material's tracking performance under specified testing; they do not directly assign a busbar working-voltage rating. Match the report to the delivered material and surface state, then review insulation geometry and validation against the equipment requirements.
Separate material indices from assembly acceptance
IEC 60112:2025 describes CTI for material comparison and PTI for acceptance and quality control using AC testing. The current publication incorporates the February 2026 corrigendum. Identify the edition actually used in a report; do not relabel an older test as a newer edition.
We recommend separate records for tracking, insulation resistance and dielectric withstand. Passing a material plaque does not establish acceptance of the formed covering, holes or joint setbacks on the final busbar.
Match the report to the delivered insulation
Review manufacturer, exact grade, formulation or color, sample thickness, surface, conditioning and results. Resolve missing information with the material supplier and establish correspondence to delivered lots and substitute materials. Retaining only a CTI number loses important context.
IEC's public description identifies composition and surface condition as factors affecting results. Review differences after forming, heating, bonding or coating. One layer's report does not automatically characterize a multilayer insulation system.
Review actual paths and equipment conditions
IEC cautions that results cannot directly establish safe equipment creepage distances. Use the applicable equipment standard and insulation-coordination requirements to establish voltage, overvoltage, pollution, paths and insulation function. No universal clearance or creepage value is supplied here.
We recommend marking covering ends, hole edges, cutouts and potentially contaminated surfaces, then agreeing sample inspection and electrical tests. Keep incomplete material approval pending review; more thickness or a passed withstand test does not resolve missing tracking evidence.
- Match edition, material grade and specimen state
- Separate material reports from assembly acceptance
- Review equipment-specific paths and substitute materials
Frequently asked questions
Does CTI 600 mean continuous operation at 600 V? No. It is a material index under defined testing, not a busbar working-voltage rating.
Can a withstand report replace tracking review? Review both against the equipment requirements; their purposes differ.
RFQ inputs for insulation review
Provide geometry, insulation grade, CTI or PTI reports, environment, working voltage and applicable equipment standard. Identify permitted substitutions and agree samples, missing documentation and change-triggered review before freezing material selection.
Apply this guide to a project
Use product pages to identify the hardware family and the calculator for early estimates only. Acceptance depends on drawings, operating conditions and project tests.