CSA Group Explosion-Proof Enclosures for Use in Class I Hazardous Locations

Preface Products evaluated to this standard are applied in hazardous locations which are defined as buildings, or parts thereof in which:  (a) an explosive gas atmosphere is present, or may be present, in the air in quantities that require special precautions for the construction, installation, and use of electrical equipment  (b) combustible dusts are present, or may be present, in the form of clouds or layers in quantities to require special precautions for the construction, installation, and operation of electrical equipment or  (c) combustible fibres or flyings are manufactured, handled or stored in a manner that will require special precautions for the construction, installation, and operation of electrical equipment.areas that are or could be a hazardous location due to the presence of an explosive gas atmosphere or (a mixture with air, under atmospheric conditions, of flammable substances in the form of gas, vapour, or mist in which, after ignition, combustion spreads throughout the unconsumed mixture).    Scope 1.1 This Standard covers the details of construction and tests for explosion-proof enclosures for electrical equipment to be used in Class I, Division 1, Groups A, B, C, and D hazardous locations and in gaseous mines in accordance with the Rules of the Canadian Electrical Code, Part I and the requirements of CSA Standard CAN3-M421-M85.  1.2 Other Standards for hazardous location equipment covering specific types of equipment shall take precedence over this Standard.  1.3 Unless otherwise marked, this Standard applies to enclosures intended for use in ambient temperatures of (a) -50 to +40°C for Class I, Groups A, B, C, and D (b) 0 to +40°C for gaseous mines (c) an oxygen concentration of approximately 21% by volume and (d) a pressure of not more than 106 kPa.