Questions and Answers
All areas designated as hazardous (classified) locations shall be properly _____ and shall be available to those authorized to design, install, inspect, maintain, or operate electrical equipment at these locations.
Documented
Hazardous (classified) locations shall be classified depending on the properties of the _____ that could be present, and the likelihood that a flammable or combustible concentration or quantity is present.
It is frequently possible to locate much of the equipment in less hazardous or unclassified locations and thus reduce the amount of special equipment required.
True
Class I, Division 1 locations are those in which ignitable concentrations of _____ can exist under normal operating conditions.
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When determining a Class I, Division 2 location, the _____ is(are) a factor(s) that should be considered in determining the classification and extent of the location.
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An area that is adjacent to a Class I, Division 1 location, and to which ignitable concentrations of flammable gases, flammable liquid-produced vapors, or combustible liquid-produced vapors above their flash points might occasionally be communicated is a _____ location.
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Class II locations are those that are hazardous because of the presence of _____.
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Locations in which combustible dust is in the air under normal operating conditions in quantities sufficient to produce explosive or ignitable mixtures are classified as _____.
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A Class II, Division 2 location is a location _____.
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Class III locations are those that are hazardous because of the presence of _____.
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Class III, Division _____ locations include areas where easily ignitable fibers/flyings are handled, manufactured, or used.
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A Class III, Division _____ location is where easily ignitable fibers/flyings are stored or handled but not manufactured.
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Electrical and electronic equipment in hazardous (classified) locations shall be protected by a(an) _____ technique.
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Dusttight protection techniques shall be permitted for equipment in Class I, Division 2 locations.
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Suitability of identified equipment for use in a hazardous (classified) location shall be determined by _____
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Equipment shall be identified not only for the class of hazardous (classified) location, but also for the explosive, combustible, or ignitable properties of the specific _____ present.
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Threaded conduits or fittings installed in hazardous (classified) locations shall be made wrenchtight to _____.
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Study Notes
General Overview of Hazardous Locations
- Hazardous (classified) locations must be properly documented and accessible to authorized personnel for designing, installing, inspecting, maintaining, or operating electrical equipment.
Classification Criteria
- Classification of hazardous locations is based on properties of:
- Flammable liquid-produced vapors
- Flammable gases
- Combustible dusts
Equipment Placement
- Equipment can often be situated in less hazardous or unclassified locations, minimizing the need for specialized equipment.
Class I Locations
- Class I, Division 1: Areas where ignitable concentrations of flammable gases or flammable liquid-produced vapors may exist under normal conditions.
- Class I, Division 2: Adjacent areas where flammable gases or vapors could potentially be communicated occasionally, influenced by:
- Quantity of flammable materials that may escape
- Ventilation adequacy
- Historical records of explosions or fires in the industry.
Class II Locations
- Class II locations are defined by the presence of combustible dust.
- Class II, Division 1: Areas where combustible dust is present in quantities capable of producing explosive mixtures.
- Class II, Division 2: Areas where combustible dust may be present due to abnormal operations, or where dust accumulations, under normal operations, could interfere with safe equipment heat dissipation.
Class III Locations
- Class III locations involve easily ignitable fibers or materials producing combustible flyings.
- Class III, Division 1: Areas where ignitable fibers are handled, manufactured, or used.
- Class III, Division 2: Areas storing or handling fibers without manufacturing.
Equipment Protection Techniques
- Electrical and electronic equipment in hazardous locations must employ protection techniques such as:
- Explosionproof
- Dust-ignitionproof
- Dusttight
- Dusttight protection is not allowed for equipment in Class I, Division 2.
Suitability and Identification of Equipment
- Equipment suitability for hazardous locations is determined by:
- Equipment listing or labeling
- Evaluations from qualified laboratories or inspection agencies
- Manufacturer's self-evaluation or engineering judgment acceptable to the authority having jurisdiction.
- Equipment must be identified not only by class but also by the specific properties of gases, vapors, dust, or fibers present.
Additional Installation Guidelines
- Threaded conduits or fittings in hazardous areas must be made wrench-tight to prevent sparking during fault currents.
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Test your knowledge on hazardous (classified) locations with these flashcards. This quiz covers important definitions and classifications required for handling electrical equipment in potentially dangerous environments. Perfect for those involved in the design, installation, and maintenance of electrical systems.
