Appendix B -Hazardous Locations Reference; North American Classification Of Hazardous Locations - Honeywell ST 3000 Installation Manual

Appendix B —Hazardous Locations Reference
Reference
Information
B.1

North American Classification of Hazardous Locations

Electrical Codes
Classifications
Divisions
2/05
Information is provided to clarify the Hazardous Location installation
requirements in North America and internationally. An explanaition of
the applicalbel enclosure classification systems is also provided.
Installation of electrical apparatus within hazardous (classified)
locations of the United States is conducted under the provisions of the
National Electrical Code (NEC), ANSI/NFPA 70, Article 500; and
within Canada, under the provisions of the Canadian Electrical Code
(CEC) C22.1, Part 1, Section 18.
In both the United States and Canada, hazardous locations are classified
into one of these three classes.
Class
I Presence of flammable gases or vapors may be present in
quantities sufficient to produce explosive or ignitable mixtures.
II Presence of combustible dusts, powders or grains.
Presence of easily ignitable fibers or flyings.
III
The classes listed above are further classified into one of the following
divisions based upon the level of risk present.
Division
1 Locations in which hazardous concentrations of flammable gases
or vapors, or combustible dust in suspension are continuously,
intermittently or periodically present under normal operating
conditions.
Locations in which flammable gases or vapors are present, but
2
normally confined within closed containers or systems from which
they can escape only under abnormal or fault conditions.
Combustible dusts are not normally in suspension nor likely to be
thrown into suspension.
ST 3000 Release 300 Installation Guide
Description of Hazardous Location
Description of Risk
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