Lockable Disconnecting Means
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Questions and Answers

Which marking color is required for the conductor or busbar with the higher phase voltage to ground on a 4-wire, delta-connected system?

  • Blue
  • Red
  • Orange (correct)
  • Yellow

    • What is the purpose of the high-leg marking on a 240/120-volt, 3-phase, 4-wire delta system?

  • To prevent problems caused by lack of standardization (correct)
  • To identify the grounded conductor
  • To indicate the phase with the highest voltage
  • To indicate the phase with the lowest voltage

    • What should electricians do to determine the location of the high leg within a system?

  • Consult UL 468A-486B tables
  • Refer to the manufacturer's instructions
  • Use suitable equipment to measure the voltage of each phase relative to ground (correct)
  • Inspect the conductor stranding

    • According to NFPA 70E, which of the following electrical equipment in other than dwelling units is required to be field or factory marked to warn qualified persons of potential electric arc flash hazards?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of proper warning labels on electrical equipment?

    <p>All of the above</p> Signup and view all the answers

    In which situations does the requirement to turn off the power before working on electrical circuits apply?

    <p>In all situations</p> Signup and view all the answers

    What information should a permanent arc flash label on service equipment and feeder supplied equipment rated 1000 amperes or more include?

    <p>All of the above</p> Signup and view all the answers

    According to NFPA 70E, when should an arc-flash risk assessment be conducted?

    <p>Whenever electrical conductors operate at 50 volts and greater</p> Signup and view all the answers

    What is the purpose of marking the available fault current at service equipment?

    <p>To verify or recalculate the available fault current after modifications</p> Signup and view all the answers

    What should be done with unused current transformers associated with potentially energized circuits?

    <p>They should be short-circuited</p> Signup and view all the answers

    What can happen if the interrupting rating or short-circuit current rating of equipment is less than the available fault current?

    <p>The equipment may not be able to safely interrupt a fault</p> Signup and view all the answers

    According to the text, what is the minimum horizontal working space required when rear access is needed to work on nonelectrical parts on the back of enclosed equipment?

    <p>30 in.</p> Signup and view all the answers

    According to the text, when are smaller working spaces permitted for low voltage electrical equipment?

    <p>All of the above</p> Signup and view all the answers

    According to the text, when can Condition 2 working clearance be permitted between dead-front switchboards, switchgear, enclosed panelboards, or motor control centers located across the aisle from each other in existing buildings?

    <p>All of the above</p> Signup and view all the answers

    Which one of the following is true about locking provisions for a cord-and-plug connection?

    <p>Locking provisions are not required to remain in place without the lock installed.</p> Signup and view all the answers

    What is the purpose of working space around electrical equipment?

    <p>To protect the equipment from intrusion by nonelectrical equipment.</p> Signup and view all the answers

    Which of the following is true about servicing and electrical preventive maintenance?

    <p>It should be performed in accordance with the original equipment manufacturer’s instructions and applicable industry standards.</p> Signup and view all the answers

    What is the minimum depth of working space required for equipment operating at 0-150 volts?

    <p>900 mm (3 ft)</p> Signup and view all the answers

    What is one way to determine the suitability of replacement parts for equipment that is not listed or field labeled?

    <p>Review the documentation that accompanies the replacement parts.</p> Signup and view all the answers

    Which condition requires a minimum clear distance of 1.2 m (4 ft) for working space?

    <p>Condition 2</p> Signup and view all the answers

    Which of the following types of electrical equipment can produce sparks during ordinary operation?

    <p>All of the above</p> Signup and view all the answers

    Under what circumstances are circuits for lighting and power allowed to be connected to a system that contains trolley wires with a ground return?

    <p>In car houses, power houses, or passenger and freight stations operated in connection with electric railways.</p> Signup and view all the answers

    According to the text, what information should be marked on reconditioned equipment?

    <p>All of the above</p> Signup and view all the answers

    According to the text, what should be done to the original listing mark on reconditioned equipment?

    <p>It should be made permanently illegible</p> Signup and view all the answers

    According to the text, in which case are the markings indicated in 110.21(A)(2) not required for reconditioned equipment?

    <p>When the equipment is located in industrial occupancies</p> Signup and view all the answers

    According to the text, what are the requirements for field-applied hazard markings?

    <p>The marking should be of sufficient durability</p> Signup and view all the answers

    Which enclosure type provides protection against rain, snow, and sleet for outdoor use?

    <p>3X</p> Signup and view all the answers

    Which enclosure type provides protection against falling liquids and light splashing for indoor use?

    <p>4X</p> Signup and view all the answers

    Which enclosure type provides protection against prolonged submersion for both outdoor and indoor use?

    <p>12K</p> Signup and view all the answers

    According to Table 110.26(A)(1), what is the minimum horizontal working clearance required for equipment operating at 151 to 1000 volts-to-ground?

    <p>2.0 m (6 ft 7 in)</p> Signup and view all the answers

    What is the voltage to ground for a 480-volt ungrounded delta system?

    <p>480 volts</p> Signup and view all the answers

    What is the reduced working space required for equipment that requires rear access for nonelectrical maintenance, such as replacing a filter?

    <p>At least 30 inches</p> Signup and view all the answers

    According to the text, what is the minimum clear distance specified in Table 110.26(A)(1) for equipment operating at that voltage and in that condition?

    <p>3 ft</p> Signup and view all the answers

    According to the text, what is the required width of the entrance to the working space for large equipment that contains overcurrent devices, switching devices, or control devices?

    <p>24 in.</p> Signup and view all the answers

    According to the text, what is the purpose of the high-leg marking on a 240/120-volt, 3-phase, 4-wire delta system?

    <p>To indicate the presence of a high voltage phase</p> Signup and view all the answers

    According to the text, what is the purpose of proper warning labels on electrical equipment?

    <p>To warn about potential electric arc flash hazards</p> Signup and view all the answers

    According to the text, what is the minimum width of the working space in front of electrical equipment?

    <p>The width of the equipment or 762 mm (30 in.), whichever is greater</p> Signup and view all the answers

    What is the minimum height of the working space for electrical equipment?

    <p>2.0 m (61/2 ft) or the height of the equipment, whichever is greater</p> Signup and view all the answers

    What is the maximum depth of the working space required to allow a door or hinged panel to open at least 90 degrees?

    <p>The depth of the equipment or 3 feet, whichever is greater</p> Signup and view all the answers

    What is the minimum clear distance required for working space in Condition 2?

    <p>1.2 m (4 ft)</p> Signup and view all the answers

    According to the text, what is the minimum elevation above the floor or other working surface for live parts of electrical equipment operating at 601 volts to 1000 volts between ungrounded conductors?

    <p>2.62 m (8 ft 7 in.)</p> Signup and view all the answers

    Which one of the following is true about the guarding of live parts by elevation?

    <p>It is correlated with requirements in ANSI/IEEE C2, National Electrical Safety Code</p> Signup and view all the answers

    In locations where electrical equipment is likely to be exposed to physical damage, what should be done to prevent such damage?

    <p>Use approved enclosures</p> Signup and view all the answers

    According to the text, what should be marked on enclosures of switchboards, switchgear, enclosed panelboards, and other electrical equipment rated not over 1000 volts nominal?

    <p>Enclosure-type number</p> Signup and view all the answers

    Which of the following is true about the dedicated electrical space for electrical equipment installation?

    <p>It must be clear of piping, ducts, leak protection apparatus, or equipment foreign to the electrical installation.</p> Signup and view all the answers

    Which of the following is true about sprinkler protection in the dedicated electrical space?

    <p>Sprinkler protection is permitted for the dedicated space where the piping complies with the section.</p> Signup and view all the answers

    What is the definition of a structural ceiling in the context of electrical equipment installation?

    <p>A dropped, suspended, or similar ceiling that adds strength to the building structure.</p> Signup and view all the answers

    What is the requirement for foreign systems installed directly above the dedicated space for electrical equipment?

    <p>They must be installed outside the dedicated space.</p> Signup and view all the answers

    Which of the following is considered large equipment?

    <p>Equipment with a combined rating of 1200 amperes or more and over 6 feet wide</p> Signup and view all the answers

    Which of the following is required for personnel doors that are less than 7.6 m (25 ft) from the nearest edge of the working space?

    <p>Listed panic hardware</p> Signup and view all the answers

    Which of the following is true about illumination in working spaces around electrical equipment?

    <p>Adjacent light sources can provide sufficient illumination</p> Signup and view all the answers

    Which of the following is true about the dedicated electrical space for equipment installations?

    <p>The space must extend from the floor to a height of 1.8 m (6 ft) above the equipment</p> Signup and view all the answers

    Which of the following enclosure types is typically used in conjunction with the term 'raintight'?

    <p>Enclosure Type 3R</p> Signup and view all the answers

    Which of the following enclosure types is typically used in conjunction with the term 'driptight'?

    <p>Enclosure Type 3</p> Signup and view all the answers

    Which of the following enclosure types is typically used in conjunction with the term 'dusttight'?

    <p>Enclosure Type 4X</p> Signup and view all the answers

    Which enclosure type provides protection against prolonged submersion for both outdoor and indoor use?

    <p>Type 4X</p> Signup and view all the answers

    Which one of these is the minimum clear distance required for working space in Condition 2?

    <p>1.2 m</p> Signup and view all the answers

    According to NFPA 70E, which of the following electrical equipment in other than dwelling units is required to be field or factory marked to warn qualified persons of potential electric arc flash hazards?

    <p>All of the above</p> Signup and view all the answers

    What is the purpose of the high-leg marking on a 240/120-volt, 3-phase, 4-wire delta system?

    <p>To indicate the phase with the highest voltage</p> Signup and view all the answers

    Which of the following types of equipment is covered by Part IV of Article 110?

    <p>Electrical enclosures</p> Signup and view all the answers

    How should high-voltage conductors be installed in tunnels?

    <p>In metal raceway</p> Signup and view all the answers

    What is the purpose of bonding and equipment grounding conductors in tunnels?

    <p>To provide a path for fault current</p> Signup and view all the answers

    What is the minimum clear distance required for working space around electrical equipment in Condition 2?

    <p>1.2 m (4 ft)</p> Signup and view all the answers

    According to the text, what is the minimum clear distance specified in Table 110.34(A) for equipment operating at 1001-2500 volts-to-ground?

    <p>1.2 m (4 ft)</p> Signup and view all the answers

    According to the text, when are smaller working spaces permitted for low voltage electrical equipment?

    <p>When there are no renewable or adjustable parts on the back of the equipment</p> Signup and view all the answers

    According to the text, what is the purpose of the high-leg marking on a 240/120-volt, 3-phase, 4-wire delta system?

    <p>To indicate the presence of a high voltage leg</p> Signup and view all the answers

    According to the text, what should electricians do to determine the location of the high leg within a system?

    <p>Check the voltage-to-ground of the high leg</p> Signup and view all the answers

    According to NFPA 70E, what is the purpose of keeping the entrance to buildings, vaults, rooms, or enclosures containing exposed live parts or exposed conductors operating at over 1000 volts, nominal, locked?

    <p>To ensure the safety of qualified persons</p> Signup and view all the answers

    According to the text, what is the minimum elevation above the floor or other working surface for live parts of electrical equipment operating at 601 volts to 1000 volts between ungrounded conductors?

    <p>1.8 m (6 ft)</p> Signup and view all the answers

    According to the text, what is the purpose of the high-leg marking on a 240/120-volt, 3-phase, 4-wire delta system?

    <p>To identify the high voltage phase</p> Signup and view all the answers

    According to the text, what is the purpose of proper warning labels on electrical equipment?

    <p>To ensure the safety of qualified persons</p> Signup and view all the answers

    Which of the following is true about the design and installation of electrical enclosures covered by Part V of this article in an industrial wiring system?

    <p>They must be designed and installed according to appropriate engineering practice, only if qualified persons monitor and supervise the system.</p> Signup and view all the answers

    What are the requirements for the design of manholes, vaults, and their means of access?

    <p>They must be designed under qualified engineering supervision and withstand all loads likely to be imposed on the structures.</p> Signup and view all the answers

    What is the purpose of design documentation for electrical enclosures covered by Part V of this article in an industrial wiring system?

    <p>To satisfy the requirements of the authority having jurisdiction.</p> Signup and view all the answers

    Which of the following is true about the working space requirements for electrical equipment?

    <p>The minimum clear work space height is 2.5 m (8 ft) and the width is 914 mm (3 ft)</p> Signup and view all the answers

    According to the text, what is the purpose of suitable guards for equipment exposed to physical damage from vehicular traffic?

    <p>To prevent foreign objects from being inserted through ventilating or similar openings</p> Signup and view all the answers

    Which of the following is true about the working space requirement for equipment located outdoors and accessible to unqualified persons?

    <p>The equipment must be elevated at least 1.2 m (4 ft) above the floor or grade level</p> Signup and view all the answers

    According to the text, what is the minimum depth of working space required for equipment operating at 0-150 volts?

    <p>914 mm (3 ft)</p> Signup and view all the answers

    Which one of these is the minimum vertical headroom required for a manhole opening located within 300 mm (1 ft) horizontally from the adjacent interior side wall of the enclosure?

    <p>1.8 m (6 ft)</p> Signup and view all the answers

    Which one of these is the minimum clear work space required where cables are located on both sides?

    <p>900 mm (3 ft)</p> Signup and view all the answers

    Which one of these is the maximum weight for a manhole access cover to be considered as meeting the requirements of 110.26(F) and 110.34(C)?

    <p>45.4 kg (100 lb)</p> Signup and view all the answers

    According to the text, what color should the terminal for the grounded conductor be identified as for receptacles, polarized attachment plugs, and cord connectors for plugs and polarized plugs?

    <p>White</p> Signup and view all the answers

    What is the purpose of re-identifying a white or gray insulated conductor as an ungrounded conductor in switch loops?

    <p>To avoid confusion with grounded conductors or neutral conductors</p> Signup and view all the answers

    According to the text, what is the required color for the insulation of the conductor attached to the screw shell of screw shell devices with attached leads?

    <p>Gray</p> Signup and view all the answers

    What is the required color for the insulation of the conductor entrance hole for the connection to the terminal intended for the grounded conductor if the terminal is not visible?

    <p>White</p> Signup and view all the answers

    Which of the following is true about the requirements for access to manholes in electrical installations?

    <p>Manhole openings must be free of protrusions that could injure personnel.</p> Signup and view all the answers

    What is the minimum size requirement for rectangular access openings in manholes?

    <p>650 mm x 550 mm</p> Signup and view all the answers

    Which of the following is true about the requirements for access to vaults and tunnels in electrical installations?

    <p>Access openings for personnel must be arranged such that a person on the inside can exit when the access door is locked from the outside.</p> Signup and view all the answers

    What is the purpose of the high-leg marking on a 240/120-volt, 3-phase, 4-wire delta system?

    <p>To indicate the presence of a high-leg conductor</p> Signup and view all the answers

    According to the text, how can an overload condition exist without being detected or responded to?

    <p>An overcurrent protective device is not present</p> Signup and view all the answers

    According to the text, when does the possibility of overload exist in multiwire single-phase and 3-phase circuits?

    <p>When the load characteristics result in additive harmonic currents in the neutral conductor</p> Signup and view all the answers

    According to the text, when is it necessary to group all conductors of a circuit together in at least one location?

    <p>When multiple circuits enter an enclosure</p> Signup and view all the answers

    According to the text, how should grounded conductors of 6 AWG or smaller be identified?

    <p>By three continuous white or gray stripes along the conductor's entire length on other than green insulation</p> Signup and view all the answers

    Which of the following is true about the grounding of conductors in multiwire branch circuits?

    <p>Grounded conductors must be connected to a terminal or busbar specifically intended for grounded or neutral conductors.</p> Signup and view all the answers

    Which of the following is true about the grounded conductor in a multiwire branch circuit?

    <p>The grounded conductor is not required to be installed with the ungrounded circuit conductors if line-to-neutral loads are not supplied by the branch circuit or feeder.</p> Signup and view all the answers

    What is the purpose of marking the grounded circuit conductors in an enclosure with multiple neutral conductors?

    <p>To prevent overloading of the neutral conductor.</p> Signup and view all the answers

    What is the concern with multiple circuits sharing a neutral conductor in a multiwire branch circuit?

    <p>The possibility of overloading the neutral conductor.</p> Signup and view all the answers

    Which of the following is true about the identification of grounded conductors in multiconductor cables?

    <p>The insulated grounded conductor(s) in a multiconductor cable shall be identified by a continuous white or gray outer finish or by three continuous white or gray stripes on other than green insulation along its entire length.</p> Signup and view all the answers

    What is the purpose of identifying the grounded conductors associated with one system from the grounded conductors of another system in a common enclosure?

    <p>To ensure proper system connections.</p> Signup and view all the answers

    Which of the following is true about the use of insulation color or stripes for grounded conductors in circuits of 50 volts or more?

    <p>Insulation that is white or gray or that has three continuous white or gray stripes can be used for other than a grounded conductor if it is permanently reidentified to indicate its use as an ungrounded conductor.</p> Signup and view all the answers

    What is the purpose of the Informational Note regarding the use of gray insulation and marking for grounded conductors?

    <p>To warn about the possibility of gray insulation being used for ungrounded conductors in existing systems.</p> Signup and view all the answers

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