eep April 10, 2025 NEC 500-590 NEC Quizzes Report a question What’s wrong with this question? You cannot submit an empty report. Please add some details. 0% Article 500-590 Part05 This quiz consists of 50 carefully selected questions covering NEC Articles 500 through 590, which provide essential guidelines for hazardous locations (Article 500), special occupancies (Article 525), and temporary installations (Article 590). These sections of the National Electrical Code focus on safety, classification of hazardous areas, material requirements, and proper installation practices for environments with heightened risks. The randomly generated questions ensure a thorough assessment of your understanding, reinforcing key principles related to explosive atmospheres, grounding requirements, temporary wiring regulations, and specific occupancy considerations. Some topics may reappear in different contexts to strengthen comprehension and application. Your feedback is invaluable! If you notice any discrepancies or have suggestions for improvement, please report them. Your insights help maintain the accuracy and effectiveness of this learning tool. Division 2 enclosures must prevent dust entry. 1 / 50 What is the minimum requirement for enclosures in Class II, Division 2 locations (502.115(B))? a. Only metallic enclosures are permitted. b. They must be dust-tight or otherwise identified for the location. c. Enclosures must be explosionproof. d. Enclosures require no special identification. Incorrect. Dust-tight or identified enclosures are mandatory. Correct! Enclosures must meet dust-tight or hazard-specific requirements. Enclosures in Division 2 must be dust-tight or identified for the specific hazards present, ensuring safety and compliance. Dust ignition protection differs from explosionproof requirements. 2 / 50 What is the requirement for explosionproof equipment in Class II locations (502.5)? a. Explosionproof equipment is always required. b. Explosionproof equipment is not required unless identified for dust ignition prevention. c. Equipment must always be sealed with putty. d. General-purpose equipment can be used with guards. Incorrect. Equipment must be identified for dust ignition protection if required. Correct! Explosionproof equipment is not mandatory unless identified for dust ignition prevention. Equipment in Class II locations must prevent dust ignition and may not require explosionproof characteristics unless specifically identified. Division 1 locations require robust containment methods. 3 / 50 What type of wiring is allowed in Class I, Division 1 locations (501.10(A))? a. Threaded rigid metal conduit (RMC) or intermediate metal conduit (IMC). b. Any non-metallic raceway. c. Open wiring methods. d. PVC conduit without restrictions. Incorrect. Division 1 requires more durable methods like RMC or IMC. Correct! Threaded RMC or IMC is required for these hazardous locations. Only robust methods like RMC or IMC are permitted due to the explosive potential of Division 1 locations. Grounding protects against static electricity and faults. 4 / 50 What grounding requirements apply to enclosures in Class I, Division 2 (501.30(B))? a. Grounding is optional if equipment is indoors. b. No grounding is required for explosionproof enclosures. c. Only grounded for equipment operating above 250 volts. d. All metallic enclosures must be bonded and grounded per Article 250. Incorrect. Grounding is mandatory for all metallic enclosures. Correct! Article 250 requires grounding of metallic enclosures. Metallic enclosures must be bonded and grounded to prevent sparks and ensure safety in hazardous environments. This article addresses low-energy systems for hazardous environments. 5 / 50 What is the primary scope of NEC Article 504 (504.1)? a. The installation of intrinsically safe apparatus and wiring in hazardous locations. b. All fire-protective signaling systems. c. High-voltage transmission lines. d. General-purpose electrical installations. Incorrect. Article 504 is specific to intrinsically safe systems in hazardous areas. Correct! The article focuses on intrinsically safe systems in hazardous locations. Article 504 applies to intrinsically safe systems designed to limit energy levels to prevent ignition in hazardous (classified) locations. Flexibility is necessary to minimize equipment vibration. 6 / 50 What is required for flexible connections in Class I, Division 1 locations (501.10(A)(2))? a. Listed flexible fittings or flexible cords terminated with listed connectors. b. Any flexible conduit without fittings is allowed. c. Flexible conduits must be less than 1 meter in length. d. Flexible connections are prohibited. Incorrect. Flexible connections must use listed components. Correct! Listed flexible fittings or cords are required. Flexible connections require listed fittings or cords to maintain safety while allowing movement or reducing vibrations. Division 2 allows broader wiring methods than Division 1, with conditions. 7 / 50 What wiring methods are acceptable in Class I, Division 2 locations (501.10(B))? a. Only RMC or IMC conduits. b. Non-metallic raceways without any restrictions. c. Wiring methods permitted for unclassified locations if they prevent the escape of gases. d. Open wiring is allowed for short runs. Incorrect. Only methods that prevent gas escape are permitted. Correct! Wiring methods must prevent gas migration. Wiring methods for unclassified locations are acceptable in Division 2 if they are sealed or designed to prevent gas migration, ensuring compliance and safety. This article focuses on environments where flammable gases and vapors are present. 8 / 50 What does NEC Article 501 cover (501.1)? a. General wiring methods for all industrial locations. b. Installations in unclassified areas only. c. Electrical equipment in Class I, Division 1 and Division 2 hazardous locations. d. Class II, Division 1 locations exclusively. Incorrect. Article 501 specifically addresses Class I locations. Correct! It governs Class I hazardous locations. Article 501 pertains to equipment and wiring in locations with flammable gases or vapors in quantities sufficient to create explosive mixtures. Article 502 focuses on specific hazards involving combustible dust. 9 / 50 What does NEC Article 502 cover (502.1)? a. Only residential wiring in hazardous areas. b. General wiring methods for industrial locations. c. Electrical installations in Class I locations. d. Electrical equipment and wiring in Class II, Division 1 and Division 2 hazardous locations. Incorrect. Article 502 addresses Class II, Division 1 and Division 2 hazardous areas. Correct! Article 502 covers electrical installations in Class II locations. Article 502 applies to locations with combustible dust that poses fire or explosion risks. Flexible cords require special termination in hazardous areas. 10 / 50 How should flexible cords be terminated in Class II, Division 1 locations (502.140(B))? a. Flexible cords are not permitted in Division 1. b. With general-purpose connectors. c. With cord connectors listed for the location or installed with a seal. d. Using wire nuts for dust-tight connections. Incorrect. Flexible cords need specific listed connectors or seals. Correct! Listed connectors or seals are mandatory for flexible cords. Flexible cords in Division 1 must use listed cord connectors or seals to maintain dusttight and ignition-proof integrity. Division 2 allows dust-tight and ignition-proof designs. 11 / 50 What types of motors are permitted in Class II, Division 2 locations (502.125(B))? a. Open-type motors with no restrictions. b. Motors with external cooling fans only. c. Dust-ignitionproof motors or totally enclosed designs like nonventilated or pipe-ventilated. d. Only totally enclosed fan-cooled motors. Incorrect. Division 2 requires specific dust-tight or ignition-proof designs. Correct! Dust-ignitionproof or enclosed designs are required. Motors must be dust-ignitionproof or use designs that prevent dust accumulation, such as totally enclosed nonventilated or pipe-ventilated motors. Thread engagement ensures safety against sparks. 12 / 50 What type of thread is required for equipment in Class I hazardous locations (500.8(E)(1))? a. NPT threads, with five threads fully engaged. b. Thread type is not specified. c. Loose threading to ensure easy disassembly. d. Metric threads only. Incorrect. NPT threads with proper engagement are required. Correct! Proper threading ensures enclosure safety. NPT threads with a minimum engagement of five threads are required to maintain explosionproof integrity in hazardous locations. Grounding ensures safety and compliance in hazardous locations. 13 / 50 What grounding requirements apply in Class I locations (501.30(A))? a. Equipment grounding conductors are optional. b. Wiring systems and equipment must comply with Article 250. c. Grounding is not required. d. Only high-voltage systems need grounding. Incorrect. Grounding compliance with Article 250 is mandatory. Correct! Grounding must align with Article 250 requirements. Grounding and bonding must follow Article 250 to ensure safety and prevent faults. Proper seal placement minimizes explosion risks. 14 / 50 How must conduit seals be placed in Class I, Division 1 locations (501.15(A))? a. No sealing is required for small enclosures. b. Within 450 mm (18 inches) of an explosionproof enclosure. c. Anywhere in the conduit run. d. Only at conduit terminations. Incorrect. Seals must be placed within specified distances from enclosures. Correct! Seals are required within 450 mm of enclosures. Seals must be within 450 mm (18 inches) of enclosures to contain explosions and prevent gas migration. Hazardous locations require specially designed luminaires. 15 / 50 What is required for luminaires in Class I, Division 1 (501.130(A))? a. Fluorescent lights only. b. Open fixtures with protective cages. c. General-purpose luminaires with LED bulbs. d. Luminaires identified for the specific hazardous location. Incorrect. General-purpose luminaires are not suitable for hazardous locations. Correct! Luminaires must be specifically identified for Class I, Division 1. Luminaires must be identified for Class I, Division 1, and capable of operating safely in explosive environments. Enclosures must be verified to meet installation requirements. 16 / 50 What testing is required for explosionproof enclosures after installation (501.5)? a. Visual inspection only. b. Field inspection and verification of proper assembly. c. Routine pressure testing every 5 years. d. No testing is required for listed enclosures. Incorrect. Field inspections are mandatory for safety. Correct! Field verification ensures compliance with listing requirements. Explosionproof enclosures must be inspected to ensure they are correctly assembled and comply with the listing requirements after installation. Class II groups address dust types like metal, carbon, and others. 17 / 50 What are the three Class II dust groups (500.6(B))? a. E, F, G. b. A, B, C. c. G, H, J. d. None, as Class II does not have groups. Incorrect. The Class II groups are E, F, and G. Correct! Class II locations have these three dust groups. Class II groups are E (metal dusts), F (carbonaceous dusts), and G (other combustible dusts like flour and grain). Lighting must prevent fibers from entering and sparks from escaping. 18 / 50 What type of luminaires is permitted in Class III, Division 2 locations (503.130)? a. General-purpose luminaires. b. Only portable lighting systems. c. Open fixtures with protective guards. d. Luminaires designed to minimize the entrance of fibers and prevent spark escape. Incorrect. General-purpose luminaires are unsuitable for hazardous areas. Correct! Luminaires must prevent fiber entry and spark escape. Luminaires must be designed to minimize fiber entry and prevent sparks, ensuring safety in hazardous environments. Detailed markings ensure the fixture’s compatibility with the location. 19 / 50 What marking is required for lighting fixtures in Class I, Division 1 (501.130(A))? a. Only the manufacturer’s name and model number. b. Class, Division, Group, and temperature ratings. c. Marking is optional for small fixtures. d. Voltage and wattage only. Incorrect. Complete markings are necessary for hazardous environments. Correct! Markings include Class, Division, Group, and temperature ratings. Lighting fixtures must be marked with the Class, Division, Group, and temperature ratings to confirm suitability for the hazardous location. Dust layers increase ignition risk. 20 / 50 What is the required surface temperature of equipment in Class II, Division 1 locations with dust layers (500.8(D)(2))? a. Only based on ambient temperature. b. No restrictions if dust is cleared regularly. c. 150°C under all conditions. d. Below the ignition temperature of the dust or 165°C, whichever is lower. Incorrect. NEC requires stricter temperature controls in dusty environments. Correct! The lower value ensures safety. The temperature must not exceed the ignition temperature of the dust or 165°C, whichever is lower, considering the insulation effect of dust layers. Division 1 involves continuous or frequent exposure to dust. 21 / 50 How are Class II, Division 1 locations defined (502.1, 500.5(C))? a. Locations with ignitable gases. b. Areas with occasional dust presence. c. Areas adjacent to Class III hazardous locations. d. Locations where combustible dust is present under normal operating conditions or due to maintenance or leaks. Incorrect. Division 1 deals with frequent or continuous dust presence. Correct! Division 1 locations involve continuous or frequent exposure to combustible dust. Class II, Division 1 locations involve hazardous dust present during normal operations or due to equipment maintenance or leaks. Division 1 requires robust, dust-tight wiring methods. 22 / 50 What wiring methods are permitted in Class II, Division 1 locations (502.10(A))? a. Open wiring methods only. b. PVC conduit without restrictions. c. Threaded RMC or IMC, Type MI cable, and listed flexible connections. d. Any wiring system approved for unclassified locations. Incorrect. Division 1 requires specific methods like RMC or IMC. Correct! Only robust and listed wiring methods are permitted in Division 1. Only threaded rigid metal conduit (RMC), intermediate metal conduit (IMC), or listed methods like Type MI cable are permitted to ensure containment and dust-tight connections. Conduit seals are designed for containment and prevention. 23 / 50 What is the purpose of conduit seals in Class I locations (501.15)? a. To physically support wiring in long runs. b. To prevent the migration of gases and flames. c. To allow for expansion and contraction of conduits. d. To separate power and control circuits. Incorrect. Seals are for containing gases and flames, not mechanical purposes. Correct! Seals prevent gas migration and flame propagation. Seals in conduits are used to prevent hazardous gases from migrating through the conduit and to contain potential explosions within enclosures. Group B addresses highly explosive gases like hydrogen. 24 / 50 What defines the Group B classification in Class I locations (501.6(A))? a. Sites storing flammable liquids. b. Presence of hydrogen or gases with similar ignition properties. c. Areas with high concentrations of dust. d. Locations with methane gas. Incorrect. Group B is specific to hydrogen and similar gases. Correct! Group B involves hydrogen and similar ignition properties. Group B classifications apply to locations with hydrogen or gases with similar explosive properties, requiring special precautions. T4 indicates a specific temperature class for hazardous locations. 25 / 50 What is the maximum surface temperature for T4-rated equipment (501.8(C))? a. No specific temperature limit applies. b. 450°C (842°F). c. 85°C (185°F). d. 135°C (275°F). Incorrect. T4 ratings are limited to 135°C. Correct! The maximum surface temperature is 135°C. T4-rated equipment must not exceed 135°C to prevent ignition in hazardous atmospheres. PVC conduits require additional safeguards in hazardous areas. 26 / 50 What additional protection is required for PVC conduit in Class I, Division 1 (501.10(A))? a. Grounding with non-metallic straps. b. Threadless fittings. c. Encasement in a concrete envelope and specific burial depths. d. No protection needed. Incorrect. PVC must be encased and buried appropriately. Correct! Concrete encasement and burial depths are required. PVC must be encased in concrete and buried with specific cover depths to prevent exposure to hazardous gases. Hazardous locations require secure and explosionproof terminations. 27 / 50 How should cables be terminated in Class I, Division 1 locations (501.15(A)(1))? a. Termination methods are optional. b. Directly spliced with wire nuts. c. Using general-purpose connectors. d. With explosionproof cable glands listed for the location. Incorrect. Only listed explosionproof cable glands are allowed. Correct! Terminations must use listed explosionproof glands. Cables must terminate using explosionproof glands that prevent the entry of hazardous gases or ignition risks. Marking ensures the equipment’s surface temperature is safe for the location. 28 / 50 What is the temperature marking requirement for equipment in Class I locations (501.8(C))? a. No marking is required if the temperature is below 100°C. b. Only for equipment over 500 volts. c. Equipment must be marked with its maximum surface temperature. d. Marking is optional if installed indoors. Incorrect. Markings are required regardless of voltage or location. Correct! Equipment must display its maximum surface temperature. Equipment must have markings indicating the maximum surface temperature to ensure compatibility with hazardous atmospheres. Markings must indicate compatibility with hazardous conditions. 29 / 50 What marking is required for equipment used in Class I, Division 2 locations (501.5)? a. Only voltage and current ratings are necessary. b. No markings are needed. c. Markings that identify suitability for Division 2 locations. d. Manufacturer’s logo only. Incorrect. Proper markings for Division 2 compatibility are mandatory. Correct! Equipment must be marked for Division 2 use. Equipment must be marked to show its suitability for Division 2 hazardous locations, ensuring proper use and compliance. Unmarked equipment has default temperature limits. 30 / 50 What are the allowable ambient temperature ranges for equipment without special marking (500.8(C)(5))? a. Above 40°C only. b. 0°C to +50°C. c. -25°C to +40°C. d. No temperature restrictions apply. Incorrect. The standard range is -25°C to +40°C. Correct! Equipment without marking must operate within this range. Equipment without special ambient temperature marking is suitable for operation in the range of -25°C to +40°C. Nonincendive means incapable of causing ignition. 31 / 50 How are nonincendive circuits defined in Class I, Division 2 (501.10(B) (3))? a. Circuits sealed with non-metallic covers. b. Circuits incapable of producing sparks. c. Circuits with energy levels too low to ignite hazardous atmospheres. d. Only high-resistance circuits. Incorrect. Nonincendive circuits operate at inherently safe energy levels. Correct! These circuits prevent ignition by limiting energy. Nonincendive circuits limit energy to levels insufficient to ignite gases or vapors, ensuring safe operation in Division 2 locations. Flexible cords need special durability and dust-tight terminations. 32 / 50 What is required for flexible cords in Class III, Division 1 locations (503.140)? a. Any type of flexible cord is allowed. b. Flexible cords must be sealed with tape. c. Cords must be listed for extra-hard usage and terminated with dust-tight connectors. d. Cords can be general purpose if protected by guards. Incorrect. Flexible cords must meet strict standards for usage and termination. Correct! Extra-hard usage cords with dust-tight connectors are required. Flexible cords must be listed for extra-hard usage and terminate in dust-tight connectors to prevent fiber intrusion and ensure durability. Dust-tight construction ensures heaters do not ignite nearby dust. 33 / 50 How must heaters be constructed in Class II, Division 2 locations (502.135(B))? a. Only radiant heaters are permitted. b. They must include built-in explosionproof thermostats. c. Heaters require no special construction. d. They must be dust-tight or otherwise identified for the location. Incorrect. Dust-tight or identified heaters are required in Division 2. Correct! Heaters must be dust-tight or identified for the location. Electrically heated equipment must be dust-tight or specifically identified for the hazards in Division 2 locations. Sealing protects against dust entering enclosures through raceways. 34 / 50 What is the minimum sealing length for a vertical raceway extending from a dust-ignitionproof enclosure (502.15)? a. 12 inches. b. 10 meters (33 feet). c. 1.5 meters (5 feet). d. Sealing is not required for vertical raceways. Incorrect. The minimum sealing length for vertical raceways is 1.5 meters. Correct! Vertical raceways must extend downward 1.5 meters to meet NEC requirements. Vertical raceways must extend at least 1.5 meters (5 feet) downward from dustignitionproof enclosures to prevent dust entry. Grounding ensures safety in all hazardous locations. 35 / 50 What is the grounding requirement for wiring systems in Class II locations (502.30)? a. No grounding is needed in Division 2. b. Grounding is optional for low-voltage systems. c. Only required for portable equipment. d. Grounding must comply with Article 250 requirements. Incorrect. Grounding compliance with Article 250 is mandatory. Correct! Wiring systems must comply with Article 250 grounding requirements. All wiring systems in Class II locations must be grounded per Article 250 for safe operation. Division 1 demands strict motor design standards. 36 / 50 What is the requirement for motors in Class II, Division 1 locations (502.125(A))? a. Motors can use open designs with guards. b. Motors must be identified for the location or totally enclosed pipe-ventilated. c. Motors must be explosionproof. d. General-purpose motors are allowed. Incorrect. Motors in Division 1 must meet stricter requirements. Correct! Motors must be identified for the location or use specific enclosed designs. Motors must either be identified for use in Class II, Division 1 or use totally enclosed pipe-ventilated designs to prevent dust accumulation. Lighting must be designed for hazardous dust conditions. 37 / 50 What type of luminaires is required in Class II, Division 1 (502.130(A))? a. Luminaires identified for Class II locations. b. Standard residential fixtures. c. Only fluorescent lights with covers. d. Portable lights with open designs. Incorrect. Only identified luminaires are suitable for Division 1. Correct! Luminaires must be identified for Class II locations. Luminaires in Class II, Division 1 must be specifically identified for such use and capable of preventing dust ignition. Division 1 signifies a high level of risk during normal operations. 38 / 50 How are Class I, Division 1 locations defined (501.1)? a. Areas only adjacent to hazardous equipment. b. Locations where flammable gases or vapors are present under normal operating conditions. c. Areas with occasional flammable gas leaks. d. Locations used for flammable material storage. Incorrect. Division 1 locations involve constant or predictable exposure to flammable gases. Correct! Division 1 signifies the higher-risk classification. Division 1 locations are those where ignitible gases or vapors exist during normal operations or are caused by frequent equipment faults. Dust-tight design is critical for safety in these locations. 39 / 50 What is required for boxes and fittings in Class II, Division 1 locations (502.10(A)(3))? a. They must be explosionproof. b. Fittings may use snap-on covers. c. No special requirements if they are indoors. d. They must be dust-tight and use threaded connections. Incorrect. Dust-tight and threaded connections are required. Correct! Dust-tight fittings with threaded connections are mandatory. Boxes and fittings must be dust-tight and use threaded bosses for secure, dust-tight conduit or cable terminations. Sealing protects against dust entering enclosures through raceways. 40 / 50 What is the minimum sealing length for a vertical raceway extending from a dust-ignitionproof enclosure (502.15)? a. Sealing is not required for vertical raceways. b. 10 meters (33 feet). c. 12 inches. d. 1.5 meters (5 feet). Incorrect. The minimum sealing length for vertical raceways is 1.5 meters. Correct! Vertical raceways must extend downward 1.5 meters to meet NEC requirements. Vertical raceways must extend at least 1.5 meters (5 feet) downward from dustignitionproof enclosures to prevent dust entry. Division 1 locations require dust-tight or enclosed wiring systems. 41 / 50 What is required for wiring methods in Class III, Division 1 locations (503.10(A))? a. Rigid metal conduit (RMC), PVC, or dust-tight wireways are required. b. Open wiring methods with guards are acceptable. c. Any general-purpose wiring method is allowed. d. Wiring methods require explosionproof enclosures. Incorrect. Only specific dust-tight wiring methods are permitted. Correct! Division 1 locations require dust-tight or enclosed wiring systems. In Division 1, rigid conduits, dust-tight wireways, and similar enclosed methods ensure the containment of fibers and flyings, preventing ignition risks. Grounding prevents static buildup and ensures safety. 42 / 50 What grounding requirements apply in Class III locations (503.30)? a. Grounding applies only to outdoor installations. b. Only motors and generators require grounding. c. Grounding is optional for Division 2 locations. d. All wiring systems and equipment must comply with Article 250. Incorrect. Grounding compliance with Article 250 is mandatory. Correct! Grounding ensures safety and compliance with Article 250. All wiring and equipment in Class III locations must be grounded in accordance with Article 250 to prevent ignition risks. Even non-conductive cables can pose risks. 43 / 50 How must optical fiber cables in hazardous locations be sealed (500.8(F))? a. Sealed to address both fire and explosion hazards. b. Using temporary insulation tape. c. Sealing is not required for optical cables. d. Only with non-metallic fittings. Incorrect. Proper sealing is critical to address hazards. Correct! Sealing is essential to ensure safety. Optical fiber cables must be sealed to mitigate fire hazards and explosion risks, as specified by NEC requirements. Seals in Class II prevent dust, not gases. 44 / 50 How must conduit seals be handled in Class II locations (502.15)? a. Only required for conduits over 10 feet. b. Conduit seals are not required for Class II. c. To prevent dust entry into dust-ignitionproof enclosures. d. Conduits must use explosionproof seals only. Incorrect. Seals are required to prevent dust entry, not for explosionproof purposes Correct! Seals must prevent dust from entering enclosures. Conduit seals must prevent dust entry into dust-ignitionproof enclosures and are not required to be explosionproof. Noncombustible materials and ventilation mitigate hazards from fibers and lint. 45 / 50 What construction is required for storage battery charging equipment in Class III locations (503.160)? a. Rooms require explosionproof enclosures. b. Rooms must be lined with noncombustible materials and well ventilated. c. No special construction is required. d. Equipment may be installed in general-purpose rooms. Incorrect. Noncombustible construction and ventilation are mandatory. Correct! Noncombustible materials and ventilation are required for safety. Battery charging equipment must be located in rooms built or lined with noncombustible materials and constructed to prevent fiber intrusion, ensuring safety. Motors must prevent fiber accumulation and ignition. 46 / 50 How must motors and generators be constructed for Class III, Division 1 locations (503.125)? a. Any motor with thermal overload protection is permitted. b. Open-type motors are acceptable with guards. c. Motors must be totally enclosed nonventilated, pipe ventilated, or fan cooled. d. Only self-cleaning textile motors are allowed. Incorrect. Only totally enclosed designs are acceptable. Correct! Motors must be fully enclosed to prevent fiber ignition. Motors must be totally enclosed to prevent fiber buildup and ignition, ensuring safe operation in hazardous environments. Class III focuses on fibers and flyings, not dust or gases. 47 / 50 What does NEC Article 503 cover (503.1)? a. Class II locations involving combustible dust. b. Class III locations with nonmetal combustible fibers and ignitible flyings. c. Only industrial locations with metal fibers. d. General wiring methods for unclassified locations. Incorrect. Class III is specific to fibers and flyings, not dust. Correct! Article 503 pertains to fibers and flyings. Article 503 addresses hazards related to nonmetal combustible fibers and ignitible flyings, such as in textile mills and woodworking plants. Intrinsic safety minimizes ignition risk by limiting energy. 48 / 50 What type of protection is “intrinsic safety” (500.7(E))? a. Only suitable for Division 1 locations. b. A method that prevents electrical faults entirely. c. Limits energy to a level incapable of causing ignition. d. Requires equipment to operate under high pressure. Incorrect. Intrinsic safety limits energy to safe levels. Correct! Intrinsic safety limits energy to prevent ignition. Intrinsic safety ensures energy levels in circuits are too low to ignite flammable atmospheres, making it safe for hazardous locations. Markings help ensure proper use and safety. 49 / 50 What marking is required for luminaires in Class II locations (502.130)? a. Manufacturer's name and model number. b. Type and maximum wattage of the lamp. c. No marking is required. d. Voltage rating only. Incorrect. Markings must include type and maximum wattage. Correct! Luminaires must be marked for type and maximum wattage. Luminaires must be marked with the type and maximum wattage of the lamp to ensure safe operation without exceeding temperature limits. Cable seals prevent the spread of hazardous gases. 50 / 50 What are the sealing requirements for cables in Class I, Division 2 (501.15(E))? a. Cables may use open splices with approved tape. b. Sealing is only necessary for high-voltage cables. c. No sealing is required for Division 2. d. Cables must be sealed to prevent gas migration. Incorrect. Proper sealing is required for safety. Correct! Cables must be sealed to prevent gas migration. Cables in Division 2 locations must be sealed to prevent gas migration through the cable core, ensuring safety. 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