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Insulation Resistance Test Record Sheet — What to Document and Why

2026年06月08日

A measurement without a record is worthless at audit. Here is exactly what an IR test record sheet must capture.

Why the Record Sheet Matters as Much as the Test

An insulation resistance reading that is not documented properly cannot defend you at an audit, an insurance claim, or a failure investigation. A complete insulation resistance test record sheet turns a raw number into legally meaningful evidence of due diligence. EK engineers see many teams capture the reading but miss the context that makes it useful.

1. Identification Fields

  • Asset ID / circuit reference — uniquely identify what was tested.
  • Date and time of test.
  • Technician name and signature.
  • Instrument model and serial number.
  • Calibration certificate reference and due date.

2. Test Conditions

The same insulation reads very differently under different conditions, so conditions must be recorded.

  1. Test voltage applied (250 / 500 / 1000 / 5000 V).
  2. Test duration (spot, 1-minute, or 10-minute PI).
  3. Ambient temperature — insulation resistance roughly halves every 10 °C rise.
  4. Humidity — surface leakage rises with humidity.
  5. Whether the circuit was isolated and discharged before test.

3. Measured Values

  • Spot resistance value with units (MΩ / GΩ).
  • For PI: 1-minute and 10-minute readings plus the calculated ratio.
  • For DAR: 30-second and 60-second readings plus the ratio.
  • Phase-to-phase and phase-to-earth values where applicable.

4. Interpretation and Pass Criteria

A number alone does not say pass or fail. The sheet must state the applicable criterion and the verdict.

  • Reference standard (IEEE 43, IEC 60204, local code).
  • Minimum acceptable value for this asset class.
  • PI interpretation: < 1 unsafe, 1-2 questionable, > 2 good.
  • Clear PASS / FAIL / RETEST verdict.

5. Trend Linkage

The real value of records appears over years. Comparing this year's reading to last year's reveals a downward trend long before an absolute failure. Store records so trend analysis is possible.

How EK Instruments Help

The EK-C350 5 kV insulation tester captures PI and DAR automatically with on-screen ratios, and the EK-F598 combo handles low-voltage circuits. Both ship with traceable calibration certificates whose serials populate the record sheet. Talk to EK service teams for a record-sheet template and calibration plan.