Equipment Protection Levels
The Level of Protection assigned to equipment is based on its likelihood of becoming a source of ignition and is often in line with Ex Zones.
The Equipment Protection Level (EPL) is based on a grading. In some case equipment may be assembled with devices with varying EPLs and this will impact the final rating and Ex Code. One example might be a higher rated device (e.g. Ma), however housed within a lower rated enclosure (e.g. Mb), resulting in a maximum Mb rating.
Group, Zone and suitable Equipment Protection Level
| GROUP I | GROUP II | GROUP III |
|---|---|---|
| Zone 0 - EPL Ma | Zone 0 - EPL Ga | Zone 20 - EPL Da |
| Zone 1 - EPL Ma, Mb | Zone 1 - EPL Ga, Gb | Zone 21 - EPL Da, Db |
| Zone 2 - EPL Ga, Gb, Gc | Zone 22 - EPL Da, Db, Dc |
EPL Ma
Equipment for installation in a mine susceptible to firedamp*, having 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, and may be left energized even in the presence of an outbreak of gas.
*Firedamp is defined as the gas typically formed in coal mines. This gas is typically methane but might also contain other flammable and explosive gasses.
EPL Mb
Equipment for installation in a mine susceptible to firedamp, having 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.
EPL Ga
Equipment suitable to be installed in Group II 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 suitable to be installed in Group II explosive gas atmospheres, having a “high” Level of Protection. This equipment is not a source of ignition in normal operation or during expected malfunctions.
EPL Gc
Equipment suitable to be installed in Group II explosive gas atmospheres, having an “enhanced” Level of Protection. The equipment 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).
EPL Da
Equipment suitable to be installed in 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 suitable to be installed in 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 suitable to be installed in 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).