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Questions and Answers

When only on Class 1 Division 2, max obtainable surface temperature exceeding ________ must be marked outside the enclosure.

100 C

Switches and circuit breakers in Division 2 locations must have enclosures identified for Class I, Division 1 locations when which condition is true?

  • Listed for Division 2
  • Hermetically sealed (correct)
  • Nonincendive circuits (correct)
  • Immersed in oil (correct)

    • Resistors and related equipment shall have enclosures identified for Class 1 Division 1 when ____________.

    no make-and-break contacts or sliding contacts and if the marked operating temperature does not exceed 80 percent of the auto-ignition temperature of the surrounding vapors.

    True or false: Transformer windings and solenoids in Class 1 Division 2 are required to be provided with enclosures.

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

    Attachment plugs and receptacles for process control instruments shall be _____________ for facilitating replacements.

    <p>locking and grounding type, cannot be separated when energized or be energized when separated, extra-hard usage flexible cord and not exceeding 900 mm, maximum current of 3 amperes.</p> Signup and view all the answers

    For Division 2 Class 1, general-purpose is allowed if __________________.

    <p>switches and circuit breakers are hermetically sealed, oil-immersed having 50 mm minimum for power contacts and 25 mm for control contacts.</p> Signup and view all the answers

    Fused or unfused disconnect and isolating switches that are not intended to interrupt current shall be permitted to be installed in ____________ enclosures.

    <p>general-purpose</p> Signup and view all the answers

    True or false: Standard plug or cartridge fuses for motors and lamps must be placed within enclosures identified for the location.

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

    For Class 1 Division 2, enclosures for windings of transformers, solenoids, or impedance coils shall be of the ________________ type.

    <p>general-purpose</p> Signup and view all the answers

    Resistors shall be provided with enclosures identified for ________, unless the resistance is nonvariable.

    <p>Class I locations</p> Signup and view all the answers

    Motors and generators in Class 1 Division 1 shall be of totally enclosed type supplied with positive pressure ventilation that will prevent energizing when not yet purged with at least ________ of air.

    <p>10 volumes</p> Signup and view all the answers

    True or false: Motors and generators in Class 1 Division 1 are allowed to be of inert gas-filled type.

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

    True or false: Rotating machines in Class 1 Division 1 can be submerged in a flammable liquid without restrictions.

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

    True or false: Motors and generators in Class 1 Division 2 that contain switches or sliding contacts must be identified for Class 1 Division 1.

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

    True or false: Motors and generators in Class 1 Division 2 are allowed to contain brushes or arc-producing devices.

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

    True or false: During shutdown periods, space heaters for motors and generators in Class 1 Division 2 must not exceed 80 percent of the autoignition temperature.

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

    True or false: A sliding contact shaft bonding device for maintaining the rotor at ground potential is prohibited in Class 1 Division 2 locations.

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

    Each luminaire shall be clearly marked to indicate the maximum __________ of lamps for which it is identified.

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

    True or false: Pendant luminaires in Class 1 locations must be suspended by and supplied through rigid conduit stems.

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

    For stems in pendant luminaires longer than _____________, permanent bracing against lateral displacement shall be provided.

    <p>300 mm (12 in.)</p> Signup and view all the answers

    Flexibility for pendant luminaires shall be provided not more than ____________ from the point of attachment.

    <p>300 mm (12 in.)</p> Signup and view all the answers

    True or false: Luminaires that may operate above 80 percent of auto-ignition temperature must be identified for Class 1 Division 1.

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

    True or false: Starting equipment for electric-discharge lamps in Class 1 Division 2 must comply with circuit breaker requirements.

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

    In Class 1 Division 2, the heater must not have a max temperature exceeding 80 percent of auto-ignition temperature when heat shall be at ______ percent rated voltage.

    <p>120</p> Signup and view all the answers

    True or false: Flexible cords are permitted in classes 1 and 2 locations if they are protected from damage.

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

    True or false: Electric submersible pumps must have removable cords that require entry into the wet-pit for servicing.

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

    True or false: Electric mixers in Class 1 and 2 locations can use flexible cords.

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

    True or false: Flexible cords in classes 1 and 2 must be of a continuous length and supported by clamps.

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

    True or false: Receptacles for classes 1 and 2 are required to have an equipment grounding conductor connection.

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

    The article number for Class 2 locations is __________.

    <p>Article 5.2</p> Signup and view all the answers

    What is Article 5.1?

    <p>Article number for Class 1 locations</p> Signup and view all the answers

    All boxes and fittings shall be _________ for Class I, Division 1.

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

    What does ER mean in cables?

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

    Where seals are required for boundary conditions, the Division 1 wiring method shall extend into the Division 2 area to the seal.

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

    Sealing compound shall be used in Type MI cable termination fittings to exclude moisture from the cable insulation.

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

    Each conduit entry into an explosionproof enclosure shall have a conduit seal, one of the requirements is when the enclosure contains apparatus that may produce arcs, sparks, or temperatures that exceed _______ of the autoignition temperature.

    <p>80 percent</p> Signup and view all the answers

    Seals are not required in explosionproof enclosure if hermetically sealed against vapors.

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

    Each conduit entry into an explosionproof enclosure shall have a conduit seal, one of the requirements is when the entry __________ or larger.

    <p>is metric designator 53 (trade size 2)</p> Signup and view all the answers

    An enclosure marked 'Leads Factory Sealed' shall be considered as a seal for another adjacent enclosure requiring a conduit seal.

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

    Conduit seals shall be installed within _______- from the enclosure.

    <p>450 mm (18 in.)</p> Signup and view all the answers

    Only threaded couplings or explosionproof fittings larger than the trade size of the conduit are permitted between the sealing fitting and the explosionproof enclosure.

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

    Conduit seals shall be installed within ___________ of the enclosure in each conduit entry into a pressurized enclosure.

    <p>450 mm (18 in.)</p> Signup and view all the answers

    Match the following distances with their requirements:

    <p>Where two or more enclosures connected by nipples = 900 mm (36 in.) Within conduit entry to an enclosure = 450 mm (18 in.) Distance from the Division 1 location boundary = 3000 mm Non-pressurized conduit distance to fitting = 300 mm (12 in.)</p> Signup and view all the answers

    The conduit run between the conduit seal and where the conduit leaves the class 1 Division 1 location must contain unions, couplings, or any other fitting.

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

    A conduit seal is required in each conduit run leaving a Division 1 location.

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

    Metal conduit that contains no unions that passes through a Division 1 and 2 location shall not require a conduit seal if the termination points are located in __________.

    <p>unclassified locations</p> Signup and view all the answers

    For underground conduit established below grade, the sealing fitting shall be installed before the conduit emerges from below grade.

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

    In Class 1, Division 2 locations, similar provisions apply as in Class 1, Division 1 regarding conduit entry into enclosures.

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

    A conduit seal shall be required in each run leaving a Class I, Division 2 location, within _______ of the boundary.

    <p>3.05 m (10 ft)</p> Signup and view all the answers

    Rigid metal conduit or threaded steel intermediate metal conduit shall be used between the sealing fitting and where the conduit leaves the Division 2 location.

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

    ______ are provided in conduit systems to minimize the passage of gases and vapors.

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

    The passage of gases, vapors, flames, through _______ cable is inherently prevented by construction.

    <p>Type MI</p> Signup and view all the answers

    Gas or vapor leakage may occur through the interstices between strands of standard stranded conductors larger than _______.

    <p>30 mm squared</p> Signup and view all the answers

    Conduit systems terminating in an unclassified location shall not be required to be sealed under certain conditions, where one condition is that the unclassified location is _______.

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

    Conduit systems passing from a room that is unclassified into a Division 2 location shall require a seal at the boundary.

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

    Segments of aboveground conduit systems must be sealed when entering from Division 2 into an unclassified location.

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

    For conduit seals in class 1, the compounds shall provide the seal and be unaffected by the temperature, with a melting point higher than ______.

    <p>93 C</p> Signup and view all the answers

    Type MC-HL cables shall be sealed after the jacket and any covering have been removed.

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

    Seals for cables entering enclosures shall be installed within ________ of the enclosure.

    <p>450 mm (18 in.)</p> Signup and view all the answers

    Shielded cables must have the shielding material removed during installation.

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

    Cables with a gas/vaportight continuously sealed sheath shall pass through a Division 2 location without seals.

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

    Cables leaving an enclosure that is unclassified as a result of pressurization must be sealed at the boundary.

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

    Cables capable of transmitting gases through the cable core shall not be required to be sealed unless the cable experiences a pressure in excess of ____________.

    <p>1500 pascals (6 in. of water)</p> Signup and view all the answers

    Cables that do not have a gas/vaportight continuous sheath shall be sealed at the boundary of Division 2 and unclassified location.

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

    Approved means should be provided to prevent accumulation or periodic draining of condensed vapor within equipment.

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

    Process-connected electrical equipment that relies on a single process seal shall not be provided with an additional means of sealing.

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

    What should insulation be made of where condensed vapors may collect?

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

    Electrical conductors shall not operate at more than __________.

    <p>30 volts (15 volts in wet locations)</p> Signup and view all the answers

    The locknut-bushing types of contacts are sufficient for bonding.

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

    The specific bonding means should be required only to the nearest point where the grounded circuit conductor and grounding electrode are connected.

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

    For Class 1, 2, 3 locations, flexible metal conduit shall not include an equipment bonding jumper.

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

    Surge-protective capacitors shall be of a type designed for __________.

    <p>specific duty</p> Signup and view all the answers

    Transformers and capacitors containing a liquid that will burn shall be installed only in vaults with ample ventilation.

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

    Transformers and capacitors that do not contain liquid that will burn should be installed in vaults.

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

    In Class 1, Division 2, transformers and capacitors shall comply with the respective chapter regulations.

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

    Study Notes

    Class 1 Locations and Articles

    • Article 5.1 identifies locations classified as Class 1, where special protective measures are required for electrical installations.
    • Conduit seals are required in certain conditions to prevent leakage of gases or vapors in Class I, Division 1 environments.

    Approved Equipment and Materials

    • All boxes and fittings must be approved for use in Class I, Division 1 settings to ensure fire and explosion safety.
    • Type MI cables and specific sealing compounds are required to prevent moisture from entering electrical systems.

    Sealing and Conduit Requirements

    • Conduit seals must be positioned within 450 mm (18 in.) of enclosures, especially where apparatus may produce heat or sparks.
    • An explosionproof enclosure must not utilize factory-sealed enclosure as a conduit seal for adjacent enclosures requiring their own seals.

    Boundary Conditions

    • Seals must extend into Division 2 areas at boundaries to protect against gas ingress and maintain safety integrity.
    • No fittings shall be included in the conduit between the seal and the Class 1, Division 1 area, except for specific types of approved fittings.

    Multi-Entry and Multi-Cable Specifications

    • Multiple enclosures connected by short lengths of conduit can share a single seal if appropriately positioned.
    • Cables with gas/vaportight sheaths require sealing at the entry point into enclosures to maintain integrity and prevent vapor escape.

    Cable Inspection and Approval Standards

    • Reactivity of materials influences requirements; cables that can transmit gases through their core must be sealed appropriately.
    • Cables installed in unclassified areas from Division 2 settings may not require seals if safety conditions are met.

    Mechanisms to Prevent Vapor Accumulation

    • Equipment in areas where condensation is probable must have measures to drain or prevent liquid accumulation.
    • Process-connected equipment should incorporate measures to mitigate risks of process fluid entry.

    Specific Material and Temperature Parameters

    • Conduits passing through Class 1 and Division 2 locations must be approved, particularly with materials designed for specific pressure and temperature conditions.
    • Conductors larger than 30 mm squared may require special construction to reduce gas leakage.

    Safety and Operational Temperature Guidelines

    • Electrical components operating above 30 volts but below specific thresholds require protective measures to avoid electrical hazards.
    • Enclosures for transformers and capacitors in Division 1 might require additional safeguards when containing flammable materials.

    Class 1 Division 2 Specific Regulations

    • General-purpose enclosures are acceptable for use under certain conditions in Division 2 without needing to meet Division 1 requirements.
    • Transformers and capacitors must comply with specific standards pertinent to their installation environment for Division 2 applications.

    Sealing Conditions and Exceptions

    • Certain electrical apparatus can operate under non-sealing conditions if designed properly and does not exceed defined operational heat conditions.
    • Process-connected electrical gear can avoid additional sealing requirements if exceeding specified limits while employing a dominant single seal design.

    Important Definitions

    • Conduit Seal: A fitting used to minimize gas passage and prevent flame propagation in electrical installations.
    • Vapor-tight Cables: Cables designed to prevent gas or vapor movement through their insulating sheath, crucial for safety in hazardous locations.

    General Safety Practices

    • Flexibility and adaptability in bonding practices are necessary to ensure consistent grounding across diverse electrical setups.
    • Detailed inspections are crucial in determining whether environment-specific enclosures meet safety standards for Class I applications.### Process Control Instruments
    • Connection of process control instruments via flexible cord and receptacle is allowed if hermetically sealed or oil-immersed.
    • Minimum spacing required: 50 mm for power contacts and 25 mm for control contacts.

    Class 1 Division 2 Equipment

    • Equipment intended to interrupt current (switches, circuit breakers, etc.) needs enclosures identified for Class I, Division 1.
    • General-purpose enclosures may be permitted.

    Disconnect and Isolating Switches

    • Fused or unfused disconnect switches for transformers in Class I, Division 2 must be in general-purpose enclosures.

    Protection of Motors and Appliances

    • Standard fuses can be used if installed in enclosures suitable for the location or if they meet specific conditions (oil immersion, hermetic sealing).

    Enclosures for Electrical Components

    • Windings for transformers and similar devices in Class I, Division 2 may use general-purpose enclosures.
    • Resistors in Class I, Division 2 must have enclosures identified for Class I locations unless resistance is non-variable and within temperature limits.

    Motors and Generators

    • In Class I, Division 1, motors must be totally enclosed, positively ventilated, purged with at least 10 volumes of clean air.
    • They must automatically de-energize when ventilation fails. Surface temperature must stay below 80% of the autoignition temperature.

    Safety Mechanisms

    • Class I, Division 1 motors may be filled with inert gas but must automatically de-energize if ventilation fails.
    • Operations in Class I, Division 2 with switches or integral resistance need to be rated for Class I, Division 1.

    Electrical Safety Regulations

    • Motors and generators in Class I, Division 2 can be non-explosion proof but must not contain arc-producing devices.
    • Space heaters in shutdown periods must not exceed 80% of the autoignition temperature and should be marked on the motor.

    Luminaire Regulations

    • Each luminaire in Class I, Division 1 must be marked with the maximum wattage rating.
    • Pendant luminaires should be supplied through threaded rigid metal conduits.

    Length Requirements for Pendant Stems

    • For pendant luminaire stems longer than 300 mm, effective bracing against displacement must be provided.
    • Flexibility in pendants is required not more than 300 mm from the attachment point.

    Luminaires Operating Conditions

    • Luminaires operating above 80% of autoignition temperature must be rated for Class I, Division 1.
    • Equipment for electric-discharge lamps and switches must comply with specific safety requirements.

    Heating Equipment Regulations

    • Heaters in Class I, Division 2 must not exceed set temperature limits, especially when not provided with temperature control.

    Flexible Cords in Hazardous Locations

    • Flexible cords can be used where fixed wiring is inadequate, but they must be protected from damage.
    • Cords in industrial settings require qualified personnel for installation and maintenance.

    Equipment Connection Standards

    • Electric submersible pumps can have flexible cords under specific conditions.
    • Flexible cords must be of high usage quality and properly managed to prevent stress at connection points.

    Electrical System Requirements

    • Receptacles must be integrated into premises wiring, and plugs must have grounding connections in hazardous locations.

    Regulatory Reference

    • Article 5.2 pertains to standards for Class 2 locations.

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