Hazardous Electrical Locations

The National Fire Protection Association (NFPA) establishes area classifications based on classes, divisions, and groups that delineate the hazardous conditions in a specific area.

In a grain handling facility, this may include enclosed areas of the facility such as tunnels, intermediate floors of a headhouse, gallery floors, boot pits, etc.

The classification method used by NFPA provides a description of the hazardous material that may be present and the probability that it is present so that the appropriate equipment may be selected and safe installation practices followed.

The Occupational Safety and Health Administration (OSHA) has adopted the classifications established by the NFPA.

Class II: Class II hazardous locations are areas where combustible dust may be present in varying hazardous amounts. Class II locations are divided further into two divisions.

Class II, Division 1: Includes areas where combustible dust is present in air under normal operating conditions in such a quantity as to produce ignitable mixtures. 

This may be continuous, intermittent, or on a periodic basis. This may include situations where an ignitable mixture could be produced by a mechanical failure or abnormal machinery operation. 

An example of Class II, Division 1 is a grain receiving tunnel with an open conveyor.

Class II, Division 2: Includes areas where dust normally will not be in suspension in air in quantities sufficient to produce explosive or ignitable mixtures, and dust accumulations normally will be insufficient to interfere with the operation of electrical equipment or other apparatuses, but combustible dust may be in suspension in air as a result of infrequent malfunctioning of handling or processing equipment.

Group G: Hazardous area classifications are broken down further into groups. A Group G area contains combustible dusts such as flour, grain, wood, or plastic.

Familiarize yourself with the hazardous area classifications in the work environment.

Use appropriately rated electrical tools in these areas, and make sure that portable or fixed electrical equipment and systems do not pose an ignition source.



Photo: Improper lighting used in a Class II, Division 1, Group G classified area.

Sources:

Source: Joe Mlynek is president of Progressive Safety Services LLC, Gates Mills, OH; joe.mlynek@progressivesafety.us; and content creation expert for Safety Made Simple, Inc., Olathe, KS; joe@safetymadesimple.com