Megger test report format: free insulation resistance test report (Excel and PDF)
Deskely Completions team Singapore
A megger test report records the insulation resistance of cables, motors and other equipment: what was tested, at which voltage, the readings between phases and to earth, the minimum required, and whether each one passed.
This page gives you a free megger test report format in Excel and PDF. The Excel version marks each line pass or fail against your minimum, and a second sheet works out the polarisation index for motors and transformers.
- Record readings between each pair of phases and from each phase to earth.
- Note the test voltage, the instrument and its calibration date on every report.
- Compare each reading with the minimum in your specification, not a rule of thumb.
- For motors and transformers, the polarisation index tells you more than one reading.
What a megger test report records
- Header: project, report number, date, system, equipment or cable type, rated voltage.
- Instrument: tester model and serial number, calibration due date.
- Conditions: ambient temperature and humidity, which affect the readings.
- Readings: for each cable or circuit, the test voltage and the insulation resistance in MΩ, L1 to L2, L2 to L3, L3 to L1, and each phase and neutral to earth.
- Result: pass or fail against the minimum value, with remarks.
The test voltage and the minimum values depend on the rated voltage of the equipment and on your specification. The insulation resistance test guide explains both, with a calculator.
The template
Enter the minimum for each line and the readings; the result column fills in Pass or Fail by itself. The second sheet takes the readings at 1 and 10 minutes and works out the polarisation index.
Polarisation index
The polarisation index (PI) is the insulation resistance after 10 minutes divided by the reading after 1 minute. Healthy, dry insulation keeps absorbing charge, so the reading rises and the PI is well above 1. Wet or contaminated insulation leaks current, so the reading stays flat.
IEEE 43 recommends a minimum PI of 2.0 for class B, F and H insulation and 1.5 for class A. The template uses 2.0 by default; change it per line if your specification differs.
Readings on a tablet instead of a sheet
On a project with thousands of cables, the readings get written on paper, typed into spreadsheets and checked weeks later, when the low reading is already behind a closed cable tray.
Deskely Verify records insulation readings against each tag on a tablet and flags values below the minimum as they are entered, so a bad cable is found on the day it is tested.
The Deskely products for this
Frequently asked questions
What is a megger test report?
A record of insulation resistance tests on cables or equipment, with the test voltage, the readings in MΩ and the result against the required minimum.
What readings go in an IR test report?
Usually phase to phase (L1 to L2, L2 to L3, L3 to L1) and each phase and the neutral to earth, at the stated test voltage after one minute.
What is a good polarisation index?
IEEE 43 recommends at least 2.0 for class B, F and H insulation and 1.5 for class A. Below 1 points to wet or contaminated insulation.
Is the template free?
Yes. Download the Excel or PDF version and adapt it to your project.
- In production since 2014
- Thousands of daily users
- On MODEC FPSO projects since 2016