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B.2 International Electrotechnical Commission (IEC)
Classification of Hazardous Locations,
Continued
IEC Methods of
Protection
The following table summarizes available methods of protection for use
in given locations.
Protection Concept Designation Permitted Use Principle
Flameproof d Zone 1 & 2 Contains explosion and
quenches flame.
Intrinsic Safety ia Zone 0, 1 & 2 Limits energy of sparks under
2 faults.
ib Zone 1 & 2 Limits energy of sparks under
1 fault
Pressurized p Zone 1 Keeps flammable gases out.
Encapsulation m Zone 1 & 2 Keeps flammable gases out.
Increased Safety e Zone 1 & 2 No arcs, sparks or hot
surface.
Powder Filled q Zone 1 & 2 Contains explosion and
quenches flame.
Oil Immersion o Zone 1 & 2 Keeps flammable gases out.
Non-sparking nA Zone 2 No arcs, sparks or hot
surfaces under normal
conditions.
Enclosed Break nC Zone 2 Contains explosion and
quenches flame.
Limited Energy nA Zone 2 Limits energy of sparks and
surface temperature under
normal conditions.
Restricted Breathing nR Zone 2 Keeps flammable gases out.
Continued on next page
90 ST 3000 Release 300 Installation Guide 2/05