INTRODUCTION

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  • HAZARDOUS AREA

    An area in which an explosive atmosphere is or may be expected to be present, in quantities such as to require special precautions for the construction, installation and use of equipment.

  • EXPLOSIVE GAS ATMOSPHERE

    Mixture with air, under atmospheric conditions, of flammable substances in the form of gas or vapor, which, after ignition, permits self-sustaining flame propagation.

  • EXPLOSIVE GAS ATMOSPHERE

    Mixture with air, under atmospheric conditions, of flammable substances in the form of gas or vapor, which, after ignition, permits self-sustaining flame propagation.

  • ELECTRICAL EQUIPMENT GROUP

    Electrical equipment for explosive atmospheres is divided into the following groups:


    GROUP I

    Electrical equipment of Group I is intended for use in mines susceptible to firedamp.


    GROUP II

    Electrical equipment of Group II is intended for use in places with an explosive gas atmosphere other than mines susceptible to firedamp.


    GROUP III

    Electrical equipment of Group III is intended for use in places with an explosive dust atmosphere other than mines susceptible to firedamp.

  • ZONES - ELECTRICAL EQUIPMENT OF GROUP II

    Hazardous areas are classified into zones based upon the frequency of the occurrence and duration of an explosive gas atmosphere, as follows:


    ZONE 0

    An area in which an explosive gas atmosphere is present continuously or for long periods or frequently.


    ZONE 1

    An area in which an explosive gas atmosphere is likely to occur in normal operation occasionally.


    ZONE 2

    An area in which an explosive gas atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only.

  • ZONES - ELECTRICAL EQUIPMENT OF GROUP III

    Hazardous areas are classified into zones based upon the frequency of the occurrence and duration of an explosive dust atmosphere, as follows:


    ZONE 20

    An area in which an explosive dust atmosphere is present continuously or for long periods or frequently.


    ZONE 21

    An area in which an explosive dust atmosphere is likely to occur in normal operation occasionally.


    ZONE 22

    An area in which an explosive dust atmosphere is not likely to occur in normal operation but, if it does occur, will persist for a short period only.