What is Calibration?
The most basic reason for calibrating an electrical instrument is to ensure that it is reading accurately. This is done by comparing the Instrument Under Test (IUT), to a Calibrator of known output and high accuracy which is known as a ‘Standard’. The second device is known as the Instrument Under Test (IUT), which is the clients electrical meter/s. When performing an electrical calibration, one makes a comparison between a Standard (Calibrator) and the Instrument Under Test (IUT) and records the results. These results are provided to the owner of the IUT, generally with Pass/Fail advice for each function of the electrical meter. The Pass/Fail is given according to weather results are within the electrical instruments (or electrical meters) manufacturers advised calibration tolerances or not.
Do you have to get calibration done for electrical meters?
In general terms; Calibration is critical to ensure equipment is both safe, and accurate. Electronic components drift as they are stressed with age. Without regular periodic calibration, the measurements made by these components are compromised, sometimes to the point where they pose a safety risk to the user. HV Testing is required by various standards and legislation on a wide variety of Electrical Safety Items and Personal Protective Equipment, in order to ensure they remain safe and are providing the level of protection that the worker requires. Almost all standards clearly state 6 monthly testing or inspection is required. In addition to this, Height Safety, Fall Arrest Equipment and Arc Flash Equipment also needs to be inspected by a trained inspector every 6 months, while Lifting or Rigging equipment needs to be inspected every 3 months.
In Queensland, under Section 22 of the Electrical Safety Regulation 2013; “a person conducting a business or undertaking must ensure that electrical work on energised electrical equipment is carried out by a competent person who has tools, testing equipment and personal protective equipment that are suitable for the work, have been properly tested, and are maintained in good working order. Failure to comply can result in a maximum of 40 Penalty Points”. The only way to ‘properly test’ electrical safety equipment and instruments is to perform full HV testing and calibration. The Electrical Safety Regulation 2002 specified a six monthly test frequency, and this should still be followed in order to adhere to best practice, and minimise liability.This is also recommended by the National Electrical Contractors Association (NECA).
In Western Australia, the SACS document requires six monthly testing and twelve monthly calibration. In New South Wales, the ISSC14 document requires six monthly testing on all safety equipment. In New Zealand, EEA’s published safety guidelines require six monthly testing on all safety equipment.
We recommend six monthly calibration and testing intervals for companies wishing to comply with National Guidelines for Electrical Testing and Calibration 2015 (MCA4000:2015).
What exactly is checked during a calibration, and what functions should be calibrated?
Electrical Calibrations include calibrations such as; multimeter calibrations, scope meter calibrations, clamp meter calibrations, insulation resistance meter (Megger) calibrations, PAT Tester calibrations, RCD Tester calibrations, Power Logger calibrations and anything else reading electrical data. Information and functions calibrated on these meters include such things as; Current, Voltage, Resistance, Frequency, Scope / Bandwidth, Temperature, Loop Impedance, Continuity to name just a few. The entirety of a meter’s functions should be calibrated, this means a variety of tests at a variety of values, for each different function available on the meter. More information on what is required to satisfy a quality calibration can be found in our National Guidelines for Electrical Testing and Calibration 2015 (MCA4000:2015).
Is checking and calibrating the same thing?
Calibration is not the equivalent of using a check box or calibration box supplied by some electrical meter manufacturers. These are simply function check boxes, the purpose of which is purely to ensure the meter is functioning at all. They do not confirm that the electrical meter is reading accurately or within tolerance. They are also not accurate enough to act as a Standard as defined above in ‘What is Calibration’. To learn more, please read our white paper on this topic by clicking here.
Does calibrating mean adjusting readings?
Calibration is defined by Calibration World Magazine as “comparison of the device under test against a traceable reference standard (Calibrator) and documentation of the results.”
Calibration is sometimes incorrectly regarded as the process of adjusting the IUT so the measurement will agree with the measurement of the standard, within a specified accuracy. Calibration does not mean adjust or bring back into specification, it just means, as described above – to compare, and to make sure an IUT is within manufacturers’ spec. Adjusting electrical instruments would be more accurately referred to as adjustment or even repair if it involves the replacement of components.