Calibration of Harris IRT Enterprises Industrial Resistance Testers is required for every ohmmeter or resistance master to ensure proper and accurate operation. There are two forms of calibration for IRT ohmmeters:

1. Standard - Resistance value for each range is listed on the unit. Resistance values are based upon the values of the precision equipment used in the unit.
2. Certified: Resistance value for each range is determined by comparison to a instrument whose calibration is traceable to the National Institute of Standards and Testing (NIST).

Factory certification is available for a nominal fee on all IRT equipment.