Mega ohmmeter (or insulation resistance tester) calibration involves verifying and adjusting the accuracy of the instrument used to measure high-resistance values, typically in electrical insulation testing. The process includes checking the meter’s output voltage, measuring accuracy across different resistance ranges, comparing readings against certified reference standards or precision resistors, and making necessary adjustments to correct any deviations. Regular calibration ensures reliable detection of insulation weaknesses, supports electrical safety, maintains compliance with industry and regulatory standards, and provides traceable records for quality assurance, preventive maintenance, and auditing purposes.