Electrical Wires and Insulation Types Quiz

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Questions and Answers

Which insulation type is moisture resistant and suitable for wet conditions?

  • THHN
  • TWHN
  • RHW-2
  • XHHW-2 (correct)

What is the temperature rating of RHW wiring insulation?

  • 1670F
  • 1200F
  • 750F
  • 900F (correct)

Which wiring type is not sunlight resistant?

  • RHW-2
  • THWN
  • TWHN-2
  • THHN (correct)

What is a characteristic of THWN insulation?

<p>Extra heat resistant (C)</p> Signup and view all the answers

Which of the following conductors has a nylon jacket that aids in sliding through conduit?

<p>TWHN (B)</p> Signup and view all the answers

What is the maximum temperature rating for THW wiring insulation?

<p>1940F (C)</p> Signup and view all the answers

Which wiring type is categorized under thermoset materials?

<p>RHW (A)</p> Signup and view all the answers

What type of insulation is widely used in modern wiring?

<p>Plastic insulation (D)</p> Signup and view all the answers

What feature differentiates XHHW-2 from other types of wiring insulation?

<p>Wet and dry rating (B)</p> Signup and view all the answers

Which insulation type is designed for moisture resistance?

<p>Moisture resistant insulation (D)</p> Signup and view all the answers

Which of the following materials is known for its extra heat resistance up to 1940F?

<p>Thermoset rubber insulation (D)</p> Signup and view all the answers

What is required for all supports and fasteners in wet locations?

<p>Corrosion-resistant materials (A)</p> Signup and view all the answers

What designation indicates a thermoplastic insulation that is heat resistant and rated for wet conditions?

<p>THW (C)</p> Signup and view all the answers

Which type of insulation was formerly used and has now become obsolete?

<p>Asbestos insulation (B)</p> Signup and view all the answers

How many quarter bends can be made in a single run between pull points?

<p>Four quarter bends (B)</p> Signup and view all the answers

What is indicated by the designation 'N' in wiring designations?

<p>Nylon jacketed insulation (A)</p> Signup and view all the answers

What is a necessary feature for wiring materials used in wet locations?

<p>Corrosion resistance or protection (B)</p> Signup and view all the answers

Which of the following is true regarding hydraulic benders?

<p>Bends can be made on-site using them (B)</p> Signup and view all the answers

Which insulation type provides protection against both heat and moisture?

<p>Extra heat resistant insulation (D)</p> Signup and view all the answers

What insulation type is known for its use in old conductors?

<p>Cloth insulation (A)</p> Signup and view all the answers

Which method helps in protecting wiring from overcurrent?

<p>Installing circuit breakers (D)</p> Signup and view all the answers

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Study Notes

Conductor Types and Insulation Ratings

  • Not Moisture Resistant: Certain conduits are unsuitable for wet conditions, with no ratings for moisture resistance.
  • Sunlight Resistance: Several types of conductors, including THW and THHN, do not withstand sunlight exposure.
  • Temperature Ratings:
    • THW-2: Thermoplastic, rated up to 194°F (900°C), not moisture or sunlight resistant.
    • RHW: Thermoset insulation (rubber/synthetic), rated 167°F (750°C), moisture and heat resistant.
    • THHN: Thermoplastic, rated 194°F (900°C), not moisture resistant.
    • XHHW-2: Thermoset (cross-linked polymer), rated 194°F (900°C), suitable for wet and dry locations.

Insulation Materials and Designations

  • Plastic Insulation: Most widely used for modern conductors, offering durability.
  • Old Insulation: Cloth and rubber materials were common in older conductor designs.
  • Common Designations:
    • A: Glass fiber
    • X: Cross-linked synthetic polymer (obsolete)
    • FEP: Fluorinated ethylene propylene
    • N: Nylon jacketed insulation
    • R: Thermoset insulation (rubber/synthetic)
    • THW: Thermoplastic with 167°F (750°C) rating.
    • HH: Extra heat resistant up to 194°F (900°C).

Wiring Methods and Regulations

  • Corrosion Resistance: All supports and hardware must use corrosion-resistant materials to ensure longevity.
  • Bend Regulations: No more than four quarter bends (360° total) between pull points in conduit installations to maintain efficiency and effectiveness.
  • Conduit Bending: 90° bends are commercially available, and hydraulic benders can be utilized on-site for installation adjustments.

Conductors for Wet Locations

  • RHH: Thermoset insulation, 194°F (900°C) temperature rating, designed for wet conditions and provides extra heat resistance.
  • Moisture and Heat Resistance: Key consideration for conductor choice in environments susceptible to varying temperatures and moisture levels.

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