Hazardous Duty Classifications Chart

Understanding hazardous location classifications is critical when selecting hoists, cranes, and controls for explosive or combustible environments.

Hazardous locations are defined by the National Electrical Code (NEC) through Classes, Divisions, and Groups. Many hoist manufacturers can furnish equipment designed to comply with these classifications.

However, NEC-compliant equipment and spark-resistant equipment are not the same thing. NEC compliance primarily relates to proper electrical enclosures and wiring methods, while spark-resistant features may include bronze trolley wheels, bronze hooks, stainless steel chain, or stainless steel wire rope.

Important Note: When specifying hoist equipment for hazardous areas, determine whether spark-resistant features are required in addition to NEC-compliant electrical enclosures and wiring. Spark-resistant features may reduce lifting capacity and increase cost.

Class Definitions

Class	Hazard Description
Class I	Flammable gases or vapors may be present in the air in quantities sufficient to produce explosive or ignitable mixtures.
Class II	Hazardous due to the presence of combustible dust.
Class III	Hazardous due to easily ignitable fibers or flyings, but not likely to be suspended in the air in quantities sufficient to produce ignitable mixtures.

Division Definitions

Division	Hazard Description
Division I	Hazardous concentrations exist continuously, intermittently, or periodically under normal operating conditions.
Division II	Hazardous materials are handled, processed, or used, but are normally confined within closed containers or systems and may escape only due to accidental rupture or breakdown.

Group Definitions

Class I Groups: Gases and Vapors

Group	Atmosphere
Group A	Acetylene
Group B	Hydrogen, or gases and vapors of equivalent hazard, such as manufactured gas
Group C	Ethyl ether vapors, ethylene, or cyclopropane
Group D	Gasoline, hexane, naphtha, benzine, butane, alcohol, acetone, benzol, lacquer solvent vapors, or natural gas

Class II Groups: Combustible Dusts