Electrical test equipment certification is important. So, with instruments subject to daily use in harsh environments regular calibration checks are essential. For electricians, ensuring the safety of a building’s wiring installation or undergoing an accreditation audit, this question is pivotal.

The Significance of Calibration Certificates

When it comes to instrument accuracy, the “Calibration Certificate” and “Certificate of Test” are the two most quoted documents. However, though often used interchangeably, these two certificates serve different purposes.

A Certificate of Test simply verifies that the instrument met the manufacturer’s specifications during production and conforms to national standards. It does not delve into the detailed measurements and results for individual test modes.

Conversely, a Calibration Certificate is more detailed, encompassing all tests and measured results performed either during production or by a separate calibration company, with relevant environmental and traceability data.

The Calibrating Journey: Factory to Field

Manufacturers often recommend an annual calibration period for their equipment. Though you should confirm this with the manual or manufacturer to ensure the instrument maintains its accuracy and reliability. But why would a modern, robustly built instrument fall out of calibration?

Instruments might drift from their specified accuracies due to factors like environmental stresses (temperature, humidity), electrical stresses, or technical failures, despite modern instruments being less prone to these influences. Remember to include overlooked components, the test leads, which are common sources of measurement error and require frequent checking.

Practical Steps Between Calibrations

1. Use a check box: Encompassing a range of known values and functions, a check box allows engineers to verify the functionality and accuracy of their instruments between calibration periods.
2. Use known circuits: Employ a circuit with known values for quick checks to ensure no significant changes have occurred in your instrument’s readings.
3. Conduct basic checks: Simple yet effective checks, such as insulation and continuity testing with leads in various configurations and checking voltage on a known good supply can identify potential issues.
4. Frequency of checks: Starting at once a month for a full functional check is sensible, and based on historical data or any detected drift, you can adjust this period.

Ensuring Ongoing Precision

In summary, a Calibration Certificate is important, and is your initial assurance of an instrument’s accuracy. But to ensure consistent performance, given the array of stresses instruments may be subject to, regular checks are indispensable. Daily, monthly, and annual checks coupled with professional calibration ensure the reliability and accuracy of your electrical testing instruments. Moreover, this also safeguards your processes and projects against potential errors.

Keep meticulous records of instrument checks and understand the calibration period recommended by the manufacturer. Vigilance for subtle wear and tear or drift in your instrument are paramount to maintaining a trustworthy electrical testing setup. And remember, it is not just about the instruments. Always keep those test leads in check, ensuring precise and safe performance in all your electrical endeavours.

Make regular checks, understand the nuances of your instruments, and elevate the accuracy and reliability of industrial electrical testing. For more information refer to the Gambica guide to instrument calibration. Gambica is the trades body representing the Instrumentation, Control, Automation and Laboratory Technology industries in the UK.