Question 1

Areas in a garage adjacent to classified locations in which flammable vapor release is unlikely (such as a storeroom) shall be unclassified where ____.

Accepted Answer

The best option is to mechanically ventilate the area at a rate of four or more air changes per hour. This helps to prevent the accumulation of flammable vapors and mitigate the risk of fire and explosion. Option A regarding negative air flow is not necessary in this scenario. Option C regarding hermetical sealing may be difficult to achieve and maintain, and option D regarding electrical wiring is not relevant to the classification of the area.

Question 2

The space adjacent to an enclosed dipping (or coating) process/apparatus is ____.

Accepted Answer

A

Question 3

Equipment markings should include markings shall include: (1) class, (2) division, (3) material classification group, (4) equipment temperature, and (5) ____.

Accepted Answer

Equipment markings should include the ambient temperature range to ensure safe operation within specified environmental conditions.

Question 4

Garages used for parking or storage are ____.

Accepted Answer

Garages used for parking or storage can be permitted to be unclassified depending on the specific codes and regulations governing the area and the type of vehicles stored. This classification allows for flexibility in the use and design of the space.

Question 5

Conduit/cable system seals minimize the passage of ____ and prevent the passage of flames from one portion of the electrical installation to another through the conduit.

Accepted Answer

Conduit/cable system seals are designed to minimize the passage of gas/vapors and prevent the passage of flames from one portion of the electrical installation to another through the conduit. They are often installed in hazardous locations where flammable gases or vapors may be present. Sealing these areas can help prevent explosions or fires from occurring. While sparks, water, and electrical flow may be potential issues in some electrical installations, they are not the primary concern addressed by conduit/cable system seals.

Question 6

Group G is the catchall group whose atmospheres contain combustible dusts not included in Group E or F, including ____.

Accepted Answer

Group G includes combustible dusts such as flour, grain, wood, plastic, and chemicals that are not covered under Group E or F.

Question 7

Flammable/combustible gases (or liquid-produced vapor) are categorized by considering ____ and minimum igniting current ratio (MIC ratio) values.

Accepted Answer

Flammable/combustible gases (or liquid-produced vapor) are categorized by considering maximum experimental safe gap (MESG) values, which indicates the minimum gap size between two electrodes that prevents ignition of a flammable mixture under specific conditions. MIC ratio values are used to assess the electrical properties of flammable/combustible gases, indicating the minimum ratio of the electrical energy required for ignition to the minimum energy required to sustain combustion. However, none of the given options are related to MESG and MIC ratio values except for choice C, which is the correct answer.

Question 8

Hazardous (classified) locations divide atmospheric identifications for Class I, Divisions 1 and 2, locations into ____.

Accepted Answer

Hazardous locations are divided into Class I, which includes locations where flammable gases, vapors, or liquids may be present, and Class II, which includes locations where combustible dust may be present. Class I locations are further divided into Divisions 1 and 2. Divisions 1 locations have a high likelihood of flammable materials being present, while Divisions 2 locations have a lower likelihood. Within Class I, both Divisions 1 and 2 are further subdivided into Groups A, B, C, and D. These groups are based on the specific type of flammable material that may be present. For example, Group A includes acetylene, while Group D includes propane.

Question 9

The simultaneous presence of flammable gases, flammable liquid-produced vapors, combustible liquid-produced vapors, or combustible dusts shall be considered when determining the ____ of the electrical equipment.

Accepted Answer

The simultaneous presence of flammable gases, vapors, or combustible dusts is a critical factor in determining the safe operating temperature of electrical equipment to prevent ignition.

Question 10

Article 515 covers a property or portion of a property where ____ are received by tank vessel, pipelines, tank car, or tank vehicle and are stored or blended in bulk for the purpose of distribution.

Accepted Answer

Article 515 covers properties or portions of properties where flammable liquids are received by tank vessel, pipelines, tank car, or tank vehicle and are stored or blended in bulk for the purpose of distribution.

Question 11

All cut ends of intermediate metal conduit (IMC) and rigid metal conduit (RMC) shall be ____.

Accepted Answer

Cut ends of IMC and RMC must be finished to remove any rough edges that could damage wires or create safety hazards. Jacketing with aluminum, composite materials, plastic, or polymer is not necessary and grounding to stable fixtures is already required by code.

Question 12

Equipment protection techniques may include explosionproof junction boxes, dusttight enclosures, heremetic sealing and ____.

Accepted Answer

Nonincendive wiring is a technique used to protect electrical equipment in hazardous locations by reducing the risk of electrical sparks that could ignite flammable gases or dust. Explosionproof junction boxes and dusttight enclosures also provide protection against explosions and dust, respectively, but hermetic sealing and damping techniques do not address the electrical ignition risk. Polycoating material and non-flammable paint are not equipment protection techniques for electrical equipment in hazardous locations.

Question 13

Sealing compound shall ____.

Accepted Answer

Sealing compound should not be affected by surrounding atmosphere or liquids in order to maintain its effectiveness in providing a seal. None of the other options listed are requirements for sealing compound.

Question 14

____ locations contain ignitable or combustible elements (gases, dust, fibers, etc.) in quantities sufficient to produce explosive (or ignitable) mixtures.

Accepted Answer

Division 1 locations are areas where ignitable concentrations of flammable gases, vapors, or liquids are likely to exist under normal operating conditions. This includes locations where the concentration of flammable substances exceeds 25% of their lower flammable limit (LFL). In these locations, special electrical equipment and wiring methods are required to prevent explosions.

Question 15

Type PVC conduit and Type RTRC conduit can be used when first surrounded by at least ____ of concrete, followed by a minimum cover of 24 in. (top of conduit to grade).

Accepted Answer

The answer of Type PVC conduit and Type RTRC conduit...

Question 16

The temperature marking for organic dusts that may dehydrate or carbonize, the temperature marking shall not exceed the lower of either the ignition temperature or ____.

Accepted Answer

The temperature marking for organic dusts that may dehydrate or carbonize should not exceed the lower of either the ignition temperature or 165°C. Therefore, the correct choice is B.

Question 17

Class II locations are hazardous because of the presence of ____.

Accepted Answer

Class II locations are hazardous because of the presence of combustible dust. Combustible dust refers to finely divided materials that can ignite or explode when dispersed in air. Common examples include wood dust, coal dust, and metal dust.

Question 18

Hazardous (classified) locations are divided into certain categories and subcategories, otherwise known as ____.

Accepted Answer

Hazardous locations are classified using classes and divisions, such as Class I, Division 1 or Class II, Division 2. These indicate the type of hazardous material present and the level of risk for ignition or explosion. Sites and subsites, sites and locations, and codes and divisions are not commonly used to classify hazardous locations.

Question 19

Additional seals apply to the ____ of the Class I locations.

Accepted Answer

The answer of Additional seals apply to the ____ of...

Question 20

Tensile stress at Type MI cable termination fittings can be avoided by ____.

Accepted Answer

Tensile stress can be avoided by proper installation and support methods, such as using strain relief devices or clamps to help distribute the mechanical load and prevent the cable from being pulled. Choosing the appropriate cable diameter, proper grounding techniques, and correct insulation methods are important for overall safety and performance, but do not directly address the issue of tensile stress.

Quiz 15: Hazardous Classified Locations