We’ve got the power! Your most common electrical test equipment calibration questions answered


Having your electrical test equipment regularly calibrated is a crucial part of its ownership. Whether it’s a portable appliance tester, RCD tester, multifunction calibrator or an insulation and continuity tester, an annual calibration will ensure your electrical test equipment is working to the correct specifications and giving you the results you expect.

Our metrology equipment calibration expert, Tom Bates, answers your commonly asked questions about electrical test equipment calibration.

Why is it important to calibrate electrical testing equipment?

When it comes to electrical safety, using inaccurate electrical testing equipment could present a number of risks and potential legal repercussions. Even a minute discrepancy in the results could pass an item that should be failing, and vice versa – making calibrations extremely important as they ensure your device is providing accurate readings.

What can cause my electrical testing equipment to give inaccurate results?

Electrical testing equipment can be easily compromised. From an electrical surge damaging the internal components, to a moisture intrusion if the device is left in storage for a long period of time, or even accidentally dropping the device or hitting it off a hard surface – your equipment might still work after such events, but you can’t be sure that it will still give you completely accurate results.

Additionally, general wear and tear through daily use can also cause the results of your device to drift over time. The shift may be small and insignificant, but in some cases, especially if you are working with small values, it may cause a slight difference in measurement.

What happens during an electrical calibration?

An electrical calibration is the process of verifying the performance of any instrument used to test or measure electrical parameters such as voltage, current or resistance.

During an electrical calibration an accredited calibration laboratory will check your equipment to make sure it is working to the correct standards. The calibration will take place under carefully controlled and maintained conditions, using a piece of reference equipment called a multifunction  electrical tester calibrator, which is at least four times more accurate than the unit under test.

After the calibration is complete, your electrical test equipment is returned with a calibration certificate which details the test performed and the results.

Your calibration certificate is your proof that your equipment is working within standard; without it, you have no way of knowing whether the results you are generating are accurate or not.

How long does an electrical test equipment calibration take?

Using traditional manual, multiple-product methods with discrete resistors, decade boxes, and other custom solutions, the calibration process itself can take up to an hour.

However, at our Calibration Select laboratory in Birmingham we recently invested in Fluke’s new 5322A electrical tester calibrator. This innovative piece of testing equipment has made the calibration process four times faster, meaning we can complete a range of electrical calibrations in as little as 15 minutes!

Although the calibration itself is a quick process, if you’re sending your items to a laboratory for calibration, we strongly advise you check what the lab’s current turnaround time is and if they offer a guarantee if they don’t meet these timescales.

Can’t I just check my device’s reading against another device?

No! It’s a common misconception that two meters are ‘calibrated’ if they both give the same reading during a field comparison check. But this does not necessarily prove that the two meters are accurate as they could both be out of calibration by the same amount.

The only way to ensure your device’s accuracy levels is to calibrate it against a known standard.

Are there any questions we’ve not answered?

We hope that’s answered any questions you have about electrical test equipment calibration. If there’s something we’ve not covered, leave a question in the box below and Tom will get back to you.