Testing worksheet
Insulation Resistance Temperature Correction Calculator
Normalize a megger reading to a reference temperature so test records can be compared more consistently over time.
Correct Insulation Resistance for Temperature
Enter measured resistance, test temperature, reference temperature, and test voltage used during the insulation resistance test.
Calculator Inputs
Calculation Results
Enter values above to see calculation results
Result notes. Keep inputs, assumptions, and result together before using this value in project records.
Keep the entered values, assumptions, and result together when adding this calculation to job notes or submittal records. Final installation choices should align with the applicable code edition, equipment listing, manufacturer instructions, local amendments, and AHJ requirements.
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Formula and field context
Normalize a megger reading to a reference temperature so test records can be compared more consistently over time.
Formula context
Insulation Resistance Test Chart
An insulation resistance test chart is a calculator-led testing worksheet. It keeps megger readings, temperature correction, PI, baseline comparison, and follow-up notes together before acceptance or maintenance decisions.
Formula
Polarization index = 10-minute insulation resistance / 1-minute insulation resistance.Variables to keep with the result
- One-minute reading is the insulation resistance recorded after one minute of test voltage.
- Ten-minute reading is the insulation resistance recorded after ten minutes when PI is used.
- Temperature correction factor adjusts the measured value to a reference temperature when applicable.
- Baseline is a prior result from the same equipment or a documented acceptance basis.
Why correction is used
Insulation resistance changes with temperature, so comparing uncorrected readings can hide the real asset trend.
Keep test records complete
Record test voltage, temperature, equipment condition, and the exact test points used so future readings are comparable.