Commissioning · Free Template
Instrument Cable Insulation Resistance Test Record Template
Record megger tests of instrument and control cables: test voltage, core to core and core to earth readings, and an automatic check against the minimum insulation resistance.
Excel (.xlsx)Printable PDFFilled exampleFree, no sign up
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- How to Use sheet with steps
- Template sheet, blank and ready
- Example sheet, filled in
- 64 built in formulas
- A4 landscape print setup
- Works in Excel, Google Sheets and LibreOffice
Preview of the Filled Example
This is the Example sheet from the download, so you can see exactly how the completed instrument cable insulation resistance test record looks.
Area / systemArea 200, SYS 300
Insulation tester and cert. noIR tester, CC 24801
Minimum acceptable IR (MΩ)100
Date25 Oct 2026
Insulation resistance results
| No | Cable tag | From | To | Cores | Test voltage (V) | Core to core (MΩ) | Core to earth (MΩ) | Core to screen (MΩ) | Result | By | Remarks |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | IC 2001 | PT 2101 | JB 2001 | 2 | 500 | 2,000 | 2,000 | 2,000 | PASS | Tech A | |
| 2 | MC 2001 | JB 2001 | MAR 01 | 24 | 500 | 1,500 | 1,200 | 1,100 | PASS | Tech A | |
| 3 | IC 2002 | TT 2102 | JB 2001 | 3 | 500 | 900 | 45 | 600 | FAIL | Tech A | Low to earth, water in gland |
Cables tested:3 · Cables failed:1
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About the Instrument Cable Insulation Resistance Test Record
Insulation resistance tests find damaged sheaths, water ingress and crushed cables before energising. A clear record for every cable is part of the commissioning dossier.
How to fill in this template
- Enter the test instrument and minimum acceptable IR from the specification.
- Disconnect both ends and isolate electronics.
- Test core to core, core to earth and core to screen at the specified voltage.
- Record the lowest reading for each test.
- Investigate and retest any failed cable.
What the formulas do
- Result = PASS if the lowest of the three readings ≥ minimum IR.
- Totals at the bottom.
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Frequently Asked Questions
What test voltage for instrument cables?
Commonly 500 V DC for low voltage instrument cables; follow your specification and cable rating.
What IR value is acceptable?
Project specifications often require tens to hundreds of MΩ; values well above that are normal for new cable.
Why disconnect instruments?
The test voltage can destroy transmitter and card electronics.
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