The sense and nonsense of extremely high Insulation Resistance Values

Marketing talk or practical value?

An extremely high insulation resistance value may sound impressive, but in practice it often says very little about the quality of your product or the reliability of your measurement. More often, it’s just a number for the brochure.

For most industrial applications, it is more than sufficient to know whether the insulation is above a certain threshold value. A measurement in the gigaohm range is enough for 99% of production processes.

Chasing even higher values typically adds nothing – except a higher price tag for a tester that promises more than is actually needed.

And in the field, measuring tens of teraohms is nearly impossible. External influences such as moisture, dust, or even temperature make such results unrealistic.

How small are these currents really?

To put this into perspective, the table below shows the current corresponding to different insulation resistance values at a test voltage of 1000 V.

As you can see, the currents at teraohm levels become so small that they are practically impossible to measure reliably in real-world conditions.

Conclusion

It’s not about the biggest numbers – it’s about the right thresholds and the repeatability of your measurements. That’s what really matters in practice.

So next time you hear: “our tester measures up to teraohms”, ask yourself:
Do I really need this for my application, or am I just buying a number for the brochure?

IONIO supplies insulation resistance meters that are calibrated for the thresholds that matter in practice — not for chasing impressive-looking numbers. The Megabras 5 kV Digital Insulation Resistance Meter and the 10 kV version offer the accuracy and repeatability that production and maintenance processes actually need. Contact IONIO for advice on the right instrument for your application.