Questions and Answers
Usually, when only on class 1 division 2, general-purpose enclosures are accepted for meters, instruments, and relays, since there are exceptions, these enclosures that have maximum obtainable surface temperature exceeding ________.
100 C
Switches, circuit breakers, and make-and-break contacts of pushbuttons, relays, alarm bells, and horns shall have enclosures identified for Class I, Division 1 locations even when in division 2 locations. When is a general-purpose enclosure permitted?
Resistors, resistance devices, thermionic tubes, rectifiers, and similar equipment that are used in or in connection with meters, instruments, and relays shall have enclosures identified for class 1 division 1 even if only in division 2, general-purpose enclosure is permitted 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.
Transformer windings, impedance coils, solenoids, and other windings that do not incorporate sliding or make-or-break contacts in class 1 division 2 shall be provided with enclosures.
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To facilitate replacements, process control instruments shall be permitted to be connected through flexible cord, attachment plug and receptacle, provided that attachment and receptacle are _____________.
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For division 2 class 1, switches, circuit breakers, motor controllers, and fuses intended to interrupt current in the normal performance of the function for which they are installed shall be provided with enclosures identified for Class I, Division 1. General-purpose is allowed if __________________.
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Fused or unfused disconnect and isolating switches for transformers or capacitor banks in class 1 division 2, that are not intended to interrupt current in the normal performance of the function for which they are installed shall be permitted to be installed in ____________ enclosures.
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For the protection of motors, appliances, and lamps, standard plug or cartridge fuses shall be permitted, provided they are placed within enclosures identified for the location.
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For class 1 division 2, enclosures for windings of transformers, solenoids, or impedance coils shall be permitted to be of the ________________ type.
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For class 1 division 2, resistors shall be provided with enclosures; and the assembly shall be identified for ________.
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Motors and generators in class 1 division 1 shall be of totally enclosed type supplied with positive pressure ventilation from a clean air that will prevent energizing when not yet purged with at least _________ of air.
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Motors and generators in class 1 division 1 shall be permitted to be of totally enclosed inert gas-filled type supplied with reliable source of inert gas with only positive pressure.
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Rotating machines in industrial establishments, class 1 division 1, with restricted access, can be submerged in a flammable liquid only when vaporized and mixed with air or any gas with higher than atmospheric pressure.
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When motors and generators are in class 1 division 2, but contain switches or any sliding contacts, or integral resistance devices either while starting or while running shall be identified for class 1 division 1.
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Motors and generators shall be allowed to be open or nonexplosion-proof in class 1 division 2 but shall not contain brushes, switching mechanisms, or any arc-producing devices such as squirrel-cage induction motors.
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During shutdown periods of motors and generators in class 1 division 2, space heaters to prevent condensation of moisture shall not exceed 80 percent of the autoignition temperature of the gases.
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In class 1 division 2 locations, a sliding contact shaft bonding device for maintaining the rotor at ground potential shall be permitted where the potential discharge is determined to be nonincendive.
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Each luminaire shall be identified as a complete assembly for the Class I, Division 1 location and shall be clearly marked to indicate the maximum _________ of lamps for which it is identified.
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Pendant luminaires in class 1 locations in general shall be suspended by and supplied through threaded rigid metal conduit stems.
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For stems in pendant luminaires in class 1 locations longer than _____________, permanent and effective ___________ against lateral displacement shall be provided.
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Flexibility for pendant luminaires in the form of a fitting or flexible connector identified for the class 1 location shall be provided not more than ________ from the point of attachment to the supporting box or fitting.
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For class 1 division 2 locations, if the luminaires may operate above 80 percent of auto-ignition temperature of the surrounding gas or vapor, it must be identified for class 1 division 1.
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In other provisions for class 1 division 2 luminaires, starting equipment for electric-discharge lamps shall comply with the one in control transformers and resistors.
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In class 1 division 2, the heater must not have maximum temperature exceeding 80 percent of auto-ignition temperature of the surrounding gases. This requirement of heat shall be at ______ percent rated voltage when not provided with temperature controller.
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For connection between portable lighting equipment or other portable utilization equipment and the fixed portion of their supply circuit, the flexible cord shall be attached to the utilization equipment with a cord connector listed for the protection technique of the equipment wiring compartment.
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Flexible cords are permitted in classes 1 and 2 locations where the fixed wiring methods cannot provide the necessary degree of movement for fixed and mobile electrical utilization equipment.
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For electric submersible pumps with means for removal without entering the wet-pit, the extension of the flexible cord within a suitable raceway between the wet-pit and the power source shall be permitted.
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For electric mixers intended for travel into and out of open-type mixing tanks or vats in classes 1 and 2, flexible cord is permitted.
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For installation of flexible cords in classes 1 and 2, they shall be extra-hard usage and supported by clamps to prevent tension.
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Receptacles shall be part of the premises wiring, and attachment plugs shall have equipment grounding conductor connection, for classes 1 and 2.
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Article number for Class 2 locations is ________.
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What is Article 5.1?
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All boxes and fittings shall be _________ for Class I, Division 1.
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What does ER mean in cables?
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Where seals are required for boundary conditions, the Division 1 wiring method shall extend into the Division 2 area to the seal.
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Sealing compound shall be used in Type MI cable termination fittings to exclude moisture and other fluids from the cable insulation.
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Each conduit entry into an explosionproof enclosure shall have a conduit seal when the enclosure contains apparatus that may produce arcs, sparks, or temperatures that exceed _______ of the autoignition temperature in degrees Celsius.
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Seals are not required in an explosionproof enclosure if hermetically sealed against vapors.
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Each conduit entry into an explosionproof enclosure shall have a conduit seal when the entry is __________ or larger.
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An enclosure marked 'Leads Factory Sealed' may not be considered to serve as a seal for another adjacent enclosure required to have a conduit seal.
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Conduit seals shall be installed within _______ from the enclosure or as required by the enclosure marking.
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Only threaded couplings or explosionproof fittings larger than trade size of the conduit are permitted between the sealing fitting and the explosionproof enclosure.
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Conduit seals shall be installed within ___________ of the enclosure in each conduit entry into a pressurized enclosure.
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Where two or more explosionproof enclosures are connected, a single conduit seal is sufficient if located not more than _____ long.
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The conduit run between the conduit seal and the point at which the conduit leaves the Class 1 Division 1 location shall contain no union, coupling, box, or other fitting except for a listed explosionproof reducer.
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A conduit seal is required in each conduit run leaving a Division 1 location.
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Metal conduit that has no fittings within ________ of either side of the boundary shall not require a conduit seal if termination points are in unclassified locations.
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For underground conduit, the sealing fitting can be installed before the conduit emerges from below grade.
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In Class 1, Division 2 locations, if the conduit enters an explosionproof enclosure, the same provisions for Class 1, Division 1 apply.
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A conduit seal shall be required in each conduit run leaving a Class I, Division 2 location within _______ of the boundary.
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For Class 1 Division 2, metal conduit shall be used between the sealing fitting and the point at which the conduit leaves the Division 2 location.
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______ are provided in conduit and cable systems to minimize the passage of gases and vapors.
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The passage of gases, vapors, flames through _______ cable is inherently prevented by the cable's construction.
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Gas or vapor leakage may occur through the interstices between strands of standard stranded conductors larger than _______.
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Conduit systems terminating in an unclassified location do not require sealing under certain conditions.
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Conduit systems passing from a pressurized unclassified room into a Division 2 location require a seal at the boundary.
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Segments of aboveground conduit systems do not need to be sealed when passing from a Division 2 location into an unclassified location if certain conditions are met.
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For conduit seals in Class 1, the compounds shall have a melting point higher than ______.
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For conduit seals in Class 1, the thickness of the compound shall be greater than trade size and not less than ______.
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The cross-sectional area of conductors shall be less than _________ of the conduit.
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Type MC-HL cables shall be sealed with a listed fitting after removing the jacket.
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Seals for cables entering enclosures shall be installed within ________ of the enclosure.
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Shielded cables and twisted pair cables require shielding material to be removed before sealing.
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Cables with a gas/vaportight continuous sheath can be sealed in Class 1, Division 1 locations by surrounding each insulated conductor.
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Multiconductor cables with a gas/vaportight continuous sheath shall be sealed within ________ of the enclosure.
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Each multiconductor cable installed in conduit shall be considered as a single conductor if it can transmit gases or vapors.
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Cables with an unbroken gas/vaportight continuous sheath are allowed to pass through a Division 2 location without seals.
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Cables leaving an unclassified room that is pressurized into a Division 2 location require a seal at the boundary.
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Cables with a gas/vaportight continuous sheath shall not be sealed unless the cable is attached to process equipment causing pressure in excess of ____________.
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Cables without a gas/vaportight continuous sheath need sealing at the boundary of Division 2 and unclassified location.
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Means must be provided to prevent accumulation of liquid or condensed vapor in enclosures for control equipment.
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Process-connected electrical equipment that relies on a single process seal does not require an additional means of sealing.
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Insulation on conductors that may contact liquids must be protected by a sheath of _______ or approved means.
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There shall be no uninsulated exposed parts that operate at more than __________.
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The locknut-bushing and double-locknut types of contacts are sufficient for bonding purposes.
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Specific bonding means are required only to the nearest point where the grounded circuit conductor and the grounding electrode are connected.
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Flexible metal conduit must include a bonding jumper of the wire type.
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In Class I and II, Division 2 locations, bonding jumpers may be deleted under certain conditions.
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Surge-protective capacitors shall be of a type designed for __________.
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In Class 1 Division 1, transformers containing liquid that burns must be installed in vaults with no doors.
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Transformers in Class 1 Division 1 that do not contain burning liquids must comply with vault specifications.
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In Class 1 Division 2, transformers must comply with the specifications of their respective chapters.
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Study Notes
Article 5.1 Overview
- Article 5.1 pertains to specific requirements for Class I locations, addressing installation and safety standards for electrical systems in hazardous environments.
Definitions and Key Concepts
- Approved: Refers to the necessity for all equipment and fittings to be certified safe for use in Class I, Division 1 locations.
- ER in Cables: Stands for "exposed," indicating an area where cable insulation may be subject to hazards.
Sealing Requirements
- Boundary seals in Division 1 must extend into Division 2 areas, with the seal located on the Division 2 side.
- Sealing compounds for Type MI cable must effectively exclude moisture.
- A conduit entry into explosive enclosures requires a seal if apparatus could produce sparks or exceed 80% of the autoignition temperature of gases.
Conduit and Cable Seal Specifications
- Conduit seals must be installed within 450 mm (18 inches) from the enclosure.
- Seals are not mandatory if the enclosure is hermetically sealed or otherwise marked.
- Between connected explosionproof enclosures, a single seal is sufficient if located within specified distances.
Installation Rules
- Only certain fittings such as threaded couplings are allowed between sealing fittings and enclosures.
- Conduit runs from Division 1 to Division 2 must not contain unions or couplings except explosionproof reducers.
Conduit Exemption Conditions
- Metal conduit that cleanly passes through Division 1 and 2 locations without fittings doesn’t require sealing if both ends are in unclassified locations.
- Conditions for not requiring seals when transitioning from Division 2 to unclassified locations include ensuring the non-incorporation of ignition sources.
Cable Requirements and Seals
- Type MI cables prevent gas and vapor transmission through their construction.
- Sealing access points within 450 mm (18 inches) of enclosures is mandated for multi-conductor cables with gas/vaportight sheaths.
- Cables with a gas/vaportight continuous sheath can pass through Division 2 locations without seals.
Additional Safety Measures
- Transformers and capacitors containing flammable liquids must be in vaults with specified safety features.
- Effective bonding must be ensured between electrical systems and grounding points in all classes.
Special Conditions and Exemptions
- Surge-protective capacitors must cater to specific duty ratings and conditions.
- Equipment designed for Class I, Division 1 can sometimes be housed in general-purpose enclosures in Division 2 under certain conditions.
Temperature and Conductivity Standards
- No exposed electrical conductors should operate above 30 volts (or 15 volts in wet locations) without protective measures.
- Transformer enclosures with maximum surface temperatures exceeding 100°C must be clearly marked.
These notes summarize critical safety and installation requirements from Articles 5.1 - 5.4, emphasizing the importance of proper sealing, equipment certification, and safety in hazardous environments.### Electrical Safety Standards
- Process control instruments allowed to connect through flexible cord, provided attachments and receptacles are hermetically sealed or oil-immersed, ensuring safety in potentially hazardous environments.
- Circuit protection devices such as switches, circuit breakers, motor controllers, and fuses in Class I, Division 2 must have enclosures identified for Class I, Division 1 to effectively interrupt current during normal operation.
- General-purpose enclosures are permitted if they comply with specific performance and safety standards, ensuring they are suitable for the intended installation.
Electrical Equipment in Hazardous Locations
- Disconnect and isolating switches for transformers or capacitor banks may be installed in general-purpose enclosures in Class I, Division 2, provided they do not interrupt current under normal conditions.
- Standard plug or cartridge fuses for motor, appliance, and lamp protection must be housed in enclosures specified for the location or be immersed in oil or other approved liquids for safety.
- Transformers, solenoids, and impedance coils enclosures in Class I, Division 2 can be of the general-purpose type, ensuring compliance with safety standards.
Motor and Generator Regulations
- Resistors in Class I, Division 2 require enclosures identified for Class I locations, unless the resistance is non-variable and meets specific temperature restrictions.
- Motors and generators in Class I, Division 1 must be of totally enclosed type and supplied with positive pressure ventilation, preventing energizing until purged with at least 10 volumes of clean air.
- In Division 1, motors may also be of the inert gas-filled type, designed to de-energize during ventilation failure, with surface temperatures not exceeding specified limits.
Special Safety Conditions
- Rotation machines in Class I, Division 1 facilities can only be submerged in flammable liquids under controlled conditions to prevent ignition risks, requiring automatic de-energizing mechanisms.
- Motors and generators featuring switches, sliding contacts, or integral resistance devices in Class I, Division 2 must be identified for Class I, Division 1 standards.
- Non-explosion-proof motors and generators in Class I, Division 2 must avoid components that can create arcs or sparks, like brushes or switching mechanisms.
Lighting and Heating Equipment
- Luminaries in Class I, Division 1 must be clearly marked regarding the maximum wattage of lamps permissible for safety and compliance.
- Pendant luminaires require suspension via threaded rigid metal conduit to prevent loosening, with specific bracing protocols for longer stems.
- For luminaires in Class I, Division 2, if operating above 80 percent of the auto-ignition temperature, identification for Class I, Division 1 is mandatory.
Flexible Cord Regulations
- Flexible cords for portable lighting and electrical equipment must be connected using specific cord connectors listed for the protective method of the equipment’s wiring compartment.
- Extra-hard usage flexible cords allowed in Classes 1 and 2 must be properly secured and supported, ensuring safety and minimizing damage risks.
- Flexible cords can be used for electric submersible pumps and mixers where mobility is required, provided all safety measures are observed.
General Provisions
- Receptacles must be part of premises wiring systems, and attachment plugs should have grounding connections to enhance safety in Classes 1 and 2 locations.
- Complying with Article 5.2 covers regulations for Class 2 locations, underscoring the importance of adherence to safety standards across various electrical installations.
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Test your knowledge with these flashcards covering Articles 5.1 to 5.4 related to electrical standards. Each card presents key terms and definitions relevant to Class I and Division wiring methods. This quiz is perfect for those studying electrical codes and safety regulations.
