2. General IS rules

2.1 Equipment classification

• According to the general rules of standard EN 50014 (1992), equipment for potentially explosive atmospheres is classified according to :

  • protection mode ;

  • industry group: group I for firedamp mines; group II for surface industries;

  • Group II subdivision, which characterizes the level of danger due to the atmosphere; for intrinsically safe equipment, this subdivision is based on the minimum ignition current (MIC), defined as the smallest current which, when flowing in a given circuit, causes ignition of the atmosphere surrounding the electrodes of a standardized device, known as a spark gap