Equipment Protection Level

In an explosive atmosphere, only suitable equipment must be installed: suitable means that they cannot ignite the explosive atmosphere.

Each Equipment, electrical or only with mechanical parts, must be declared suitable for use in a certain explosive atmosphere. Excluding the mines, where only equipment Group I can be installed, Equipment can be declared suitable for installation where there is the risk of presence of explosive Gases or Vapours (vapours are generated by the evaporation of liquids), Group II, or dust, Group III.

Each equipment that can ignite an explosive atmosphere must be given a certain level of protection or of Risk Reduction, implemented in the equipment itself. That is called Equipment Protection Level. EPL indicates the risk of ignition intrinsic to the equipment, independently from the type of protection adopted. It was recognized that it‟s advantageous to identify and mark all the products based on their intrinsic risk of ignition. This should make easier the equipment selection.

Here is the definition:

[IEC 60079: 2017] 3 Terms and definitions

3.33 Equipment protection level (EPL): level of protection assigned to equipment based on its likelihood of becoming a source of ignition and distinguishing the differences between explosive gas atmospheres, explosive dust atmospheres, and the explosive atmospheres in mines susceptible to firedamp.

For Mines, only two levels are defined (the analogy of Zone 20 and Zone 21 for dust):

• EPL Ma: It gives a “very high” level of protection, which has sufficient security that it is unlikely to become an ignition source in normal operation, during expected malfunctions or during rare malfunctions, even when left energized in the presence of an outbreak of gas
• EPL Mb: it gives a “high” level of protection, which has sufficient security that it is unlikely to become a source of ignition in normal operation or during expected malfunctions in the time span between there being an outbreak of gas and the equipment being de-energized

For Gas, three levels of protection are defined, in line with the 3 zones: Zone 0, Zone 1 and Zone 2.

• EPL Ga: equipment for explosive gas atmospheres, having a “very high” level of protection, which is not a source of ignition in:
  • normal operation,
  • during expected malfunctions or
  • during rare malfunctions
• EPL Gb: equipment for explosive gas atmospheres, having a “high” level of protection, which is not a source of ignition in
  • normal operation or
  • during expected malfunctions
• EPL Gc: equipment for explosive gas atmospheres, having an “enhanced” level of protection, which is not a source of ignition
  • in normal operation

and which may have some additional protection to ensure that it remains inactive as an ignition source in the case of regular expected occurrences (for example failure of a lamp)

For Dust, three levels of protection are defined, in line with the 3 zones: Zone 20, Zone 21 and Zone 22.

• EPL Da: Equipment for explosive dust atmospheres, having a “very high” level of protection, which is not a source of ignition in
  • normal operation,
  • during expected malfunctions or
  • during rare malfunctions
• EPL Db: Equipment for explosive dust atmospheres, having a “high” level of protection, which is not a source of ignition in
  • normal operation or
  • during expected malfunctions
• EPL Dc: Equipment for explosive dust atmospheres, having an “enhanced” level of protection, which is not a source of ignition in
  • normal operation

and which may have some additional protection to ensure that it remains inactive as an ignition source in the case of regular expected occurrences (for example failure of a lamp).