Electrical Conductor Types
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Questions and Answers

What is the minimum vertical clearance required for primary lines when crossing a highway?

  • 12 m
  • 5 m
  • 10 m (correct)
  • 7.5 m

    • Where should poles be located in relation to the road right-of-way or property line?

  • 500 mm inside the road right-of-way (correct)
  • At the center of the road right-of-way
  • 1 m from the property line
  • At the edge of the road

    • What is a requirement for the location of poles and transformer supports along public roads?

  • They must not obstruct pedestrian paths (correct)
  • They may obstruct sidewalks
  • They are allowed within the drainage canal
  • They can be placed anywhere along the road

    • Which of the following is NOT a consideration for the installation of overhead transmission lines?

    <p>Location of electric meter</p> Signup and view all the answers

    What is the minimum vertical clearance for primary lines along the side of a highly urbanized area?

    <p>7.5 m</p> Signup and view all the answers

    What happens to the heat generated in a conductor placed in an enclosed conduit compared to when it is in free air?

    <p>It is held in place and does not dissipate.</p> Signup and view all the answers

    Which type of cable is known for its highly compressed refractory mineral insulation?

    <p>Mineral Insulated Cable</p> Signup and view all the answers

    What characterizes Non-Metallic Sheathed Cable (Type NM or NMC)?

    <p>It includes multiple conductors with a flame retardant outer sheath.</p> Signup and view all the answers

    Which type of cable is specifically designed for field installation in square structural channels?

    <p>Flat Cable Assemblies</p> Signup and view all the answers

    What is the function of the moisture-resistant cable known as Type UF?

    <p>It is intended for underground connections including direct burial.</p> Signup and view all the answers

    What distinguishes Flat Conductor Cable (Type FCC)?

    <p>It consists of flat copper conductors arranged edge to edge.</p> Signup and view all the answers

    What type of cable encapsulates insulated conductors in an extruded core of moisture resistant and flame retardant material?

    <p>Shielded Non-Metallic Sheathed Cable</p> Signup and view all the answers

    Which type of cable is best characterized as having a continuous copper sheath?

    <p>Mineral Insulated Cable</p> Signup and view all the answers

    What is one advantage of flexible metal conduit wiring over rigid metal conduits?

    <p>Installation is easier and quicker</p> Signup and view all the answers

    What material covers armored cable wiring to provide protection?

    <p>Rubber or thermoplastic</p> Signup and view all the answers

    What type of wiring consists of a factory-assembled channel with conductors for two to four circuits?

    <p>Lighting track</p> Signup and view all the answers

    In surface metal raceway wiring, how are the wires supported?

    <p>On a thin sheet metal casing</p> Signup and view all the answers

    What is the maximum length for flexible metal conduit wiring?

    <p>250 ft.</p> Signup and view all the answers

    What types of cables must be used when a cable tray/open raceway is functioning as a general wiring system?

    <p>Self-protected, jacketed types</p> Signup and view all the answers

    Which type of raceway is recognized by NEC as having underfloor ducts?

    <p>Floor raceways</p> Signup and view all the answers

    What is a characteristic of ceiling raceway systems?

    <p>They have separate header and distribution ducts for power and telephone cabling</p> Signup and view all the answers

    What is the minimum vertical clearance requirement for secondary, neutral, and service lines when crossing the highway?

    <p>7.5 m</p> Signup and view all the answers

    What is the minimum distance that a pole must maintain from a fire hydrant?

    <p>5 m</p> Signup and view all the answers

    What is the minimum vertical clearance from the crown of the road pavement for poles when installed along the highway?

    <p>7.5 m</p> Signup and view all the answers

    When overhead lines are arranged for buildings exceeding 15 m in height, what is the minimum required clear space for ladder access?

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

    What minimum distance must be maintained from the curb for poles?

    <p>150 mm</p> Signup and view all the answers

    In a highly urbanized area, what minimum clearance must be observed when installing lines along the street?

    <p>7.5 m</p> Signup and view all the answers

    What requirement exists for power lines attached to buildings?

    <p>They need an Approved Attachment Plan.</p> Signup and view all the answers

    What should be avoided when positioning poles and towers near street corners?

    <p>Making them inaccessible from poles</p> Signup and view all the answers

    What is the minimum thickness required for walls of vaults constructed from reinforced concrete?

    <p>150mm</p> Signup and view all the answers

    Which type of material is acceptable for constructing the ducts for ventilation?

    <p>Fire resistant material</p> Signup and view all the answers

    What is the minimum requirement for a door sill or curb within the vault?

    <p>100mm</p> Signup and view all the answers

    How thick should the coating on the inside wall surface of hollow concrete block vaults be?

    <p>20mm</p> Signup and view all the answers

    What should be ensured regarding the location of ventilation openings?

    <p>Far away from doors and combustible materials</p> Signup and view all the answers

    Which of the following is an essential feature of entrance doors for vaults?

    <p>They should be equipped with locks.</p> Signup and view all the answers

    What is the minimum fire resistance required for construction materials used in vaults?

    <p>Two and a half hours</p> Signup and view all the answers

    How is ventilation of vaults typically achieved?

    <p>By natural circulation of air</p> Signup and view all the answers

    Study Notes

    Electrical Conductor Types and Heat Dissipation

    • Heat generated in conductors is influenced by current flow and conductor resistance; enclosed conduits limit heat dissipation compared to open air.

    Mineral Insulated Cable (Type MI)

    • Factory-assembled cable with conductors insulated using highly compressed refractory minerals within a liquid and gas-tight copper sheath.

    Non-Metallic Sheathed Cable (Type NM or NMC)

    • Known as ROMEX, this cable features two or more insulated conductors housed in moisture-resistant, flame-retardant non-metallic material.

    Shielded Non-Metallic Sheathed Cable (Type SNM)

    • Comprises insulated conductors encased in an extruded core of moisture-resistant, flame-retardant material.

    Underground Feeder and Branch Circuit Cable (Type UF)

    • Moisture-resistant cable designed for underground use, allowing for direct burial as a feeder or branch circuit.

    Flat Cable Assemblies (Type FC)

    • Consist of parallel conductors integrated with insulating material for efficient field installation in square structural channels.

    Flexible Metal Conduit Wiring

    • Easier installation compared to rigid metal conduits, available in lengths from 25 ft to 250 ft, accommodating various cable sizes.

    Armored Cable Wiring (BX)

    • Contains rubber or thermoplastic covered wires with layers of flexible steel armor for protection against moisture and physical damage.

    Surface Metal Raceway Wiring

    • Thin sheet steel casings support exposed wires, must be continuous between outlets and junctions, used for general wiring.

    Cable Tray/Open Raceway

    • Provides continuous support for approved cables, required to be self-protected and jacketed types when used in general wiring systems.

    Floor Raceways

    • NEC recognizes three types:
      • Underfloor Ducts (UF) installed beneath flooring systems.
      • Designed for strategic placement to accommodate cabling needs.

    Power Line Clearance Regulations

    • Primary lines require a vertical clearance of 10 m from road pavements.
    • Secondary lines must maintain a clearance of at least 7.5 m.

    Pole and Structure Placement

    • Poles should not obstruct pedestrian paths or drainage.
    • Transformers and power lines need approved attachment plans and must allow sufficient clearance for maintenance.

    Vault Construction Requirements

    • Walls and roofs must be robust, using reinforced concrete or masonry, with specific thickness guidelines.
    • Adequate fire resistance and ventilation to manage transformer heat levels are critically enforced.

    Ventilation Standards

    • Ventilation openings must be placed away from combustible materials, ensuring effective air circulation to control temperature within transformer vaults.

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    Description

    This quiz covers various types of electrical conductors, including their construction and thermal characteristics. You'll learn about Mineral Insulated Cable, Non-Metallic Sheathed Cable, and more, focusing on their applications and properties. Test your knowledge on how these conductors manage heat dissipation and their practical uses.

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