2. Ohmmeters for measuring insulation resistance

While the inspection of the dielectric strength of low-voltage electrical equipment prescribed by standard NF C 20-030: "Protection against electric shock", is reserved for the testing of new or refurbished equipment due to its destructive nature, the periodic monitoring of insulation resistance values during their operating periods is one of the bases for their preventive maintenance. The aforementioned standard specifies thresholds of 1 MΩ for Class I equipment and 7 MΩ for Class II equipment.