Electrical Installation and Maintenance NC III Test
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Questions and Answers

What is the required floor covering for under-floor raceway installed beneath concrete or other flooring materials?

  • Linoleum
  • Laminated Steel
  • Metal Clad (correct)
  • Glass

What is the maximum allowable cross-sectional area of all conductors or cables in relation to the interior cross-sectional area of the cell or header?

  • 50%
  • 30% (correct)
  • 25%
  • 40%

What amount of current will be drawn by an incandescent bulb connected to a 115-volt circuit with a resistance of 264.5 ohms?

  • 0.43 amps (correct)
  • 0.42 amps
  • 0.45 amps
  • 2.3 amps

When measuring ballast resistance, what is the proper condition for the source?

<p>De-energized (C)</p> Signup and view all the answers

What function does a circuit breaker perform?

<p>Protects against current surges and overloads (A)</p> Signup and view all the answers

What is the recommended method for safely de-energizing a live duplex wire?

<p>One-by-one using diagonal cutter (D)</p> Signup and view all the answers

What type of power supply is required for an electrical system with a system neutral?

<p>Wye connected Transformer (C)</p> Signup and view all the answers

What will occur if a motor's rotor is locked and it is forced to stop while in operation?

<p>Encounter high current (D)</p> Signup and view all the answers

Which type of switch is used for starting the motor?

<p>Dual motor pushbutton switch (B)</p> Signup and view all the answers

What is the required rated voltage for a six leads out motor?

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

How does the circuit breaker handle electrical faults?

<p>Through its interrupting capacity (D)</p> Signup and view all the answers

Before energizing the main circuit breaker, which condition is proper for all loads?

<p>And branch circuit breaker are de-energized (A)</p> Signup and view all the answers

What protective device is recommended to prevent motor damage from recurring single phasing?

<p>Phase sensing relay (A)</p> Signup and view all the answers

Which protective device prevents accidental reversing of motor rotation due to phase reversal?

<p>Phase sequence relay (B)</p> Signup and view all the answers

The full load current of a motor is 40 Amperes. What is the minimum conductor capacity needed?

<p>125% of the full load current (A)</p> Signup and view all the answers

What happens to a 3-phase motor during single phasing due to loose cable termination?

<p>It gets burned due to overheating (C)</p> Signup and view all the answers

In a circuit containing an inductance as a magnetic coil, how does the current behave in relation to the voltage?

<p>The current will lag the voltage (C)</p> Signup and view all the answers

What method is most effective for cleaning oil spills on concrete floors?

<p>Spreading sand and then sweeping it (A)</p> Signup and view all the answers

What is the main reason for grounding the frame of a portable electric hand tool?

<p>Reduce electric shock (C)</p> Signup and view all the answers

When positioning a climbing ladder for safety, what is the recommended angle from the vertical?

<p>30 degrees (C)</p> Signup and view all the answers

Which of the following is NOT a competency covered under Electrical Installation and Maintenance NC III?

<p>Design electrical engineering plans (C)</p> Signup and view all the answers

What could potentially happen if the equipment is not properly grounded?

<p>Risk of electric shock or damage (C)</p> Signup and view all the answers

When maintaining motor control systems, what is a critical aspect to ensure functionality?

<p>Regular inspection and testing (B)</p> Signup and view all the answers

In terms of safety protocols, what should be avoided during the maintenance of electrical equipment?

<p>Working with live circuits (B)</p> Signup and view all the answers

Flashcards

Inductor Current Lag

In a circuit with an inductor (like a coil), the current will lag behind the voltage.

Oil Spill Cleanup

Oil spills on concrete floors should be treated with absorbent materials like sand, then swept up. Never use flammable liquids like gasoline.

Tool Grounding

Grounding a tool's frame creates a low-resistance path to the earth, preventing the frame from becoming energized and causing electrical shock.

Ladder Safety Angle

For safe ladder use, the base should be placed at a 75-degree angle to the wall (not 30 degrees).

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What is a motor starting switch?

A type of switch used to start a motor, typically connected in series with the motor's winding.

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What are the rated voltages of a six-lead motor?

The rated voltage is the standard voltage that the motor is designed to operate at. For a six-lead motor, it typically has two voltage ratings, like 220 volts and 440 volts.

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What is the role of a circuit breaker's "interrupting capacity"?

Circuit breakers use their interrupting capacity to handle electrical faults by interrupting the flow of current when a fault occurs.

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What safety precaution should be taken before energizing the main circuit breaker?

Before activating the main circuit breaker, it's essential to ensure all loads and branch circuit breakers are switched off. This prevents an unexpected surge of electricity during startup.

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What device protects a motor from recurring single phasing?

A phase sensing relay is specifically designed to detect and address single phasing issues in a motor. It's a critical component for preventing damage from unbalanced power supply.

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How to prevent a motor from accidentally reversing due to phase reversal?

A phase sequence relay is used to prevent motor damage caused by incorrect phase rotation. It senses the order in which phases arrive and protects against reversing.

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What amperage should a conductor for a 40 Amp motor be able to handle?

The conductor size must be large enough to carry at least 125% of the motor's full load current to ensure safe operation.

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What type of switch is used to start a motor?

A normally open pushbutton switch is commonly used to start a motor. When the button is pressed, the circuit is completed, and the motor starts to rotate.

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Under-floor raceway covering

The under-floor raceway, which is installed beneath the surface of flooring materials like concrete, must be covered with a material that offers protection and can withstand foot traffic. Examples include linoleum, glass, metal-clad, and laminated steel.

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Maximum conductor area in cell/header

The total cross-sectional area of all conductors or cables within a cell or header should not exceed 40% of the cell's or header's interior cross-sectional area. This ensures proper spacing and prevents overcrowding, which can lead to overheating and potential hazards.

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Current calculation for incandescent bulb

Ohm's Law states that the current flowing through a conductor is directly proportional to the voltage applied and inversely proportional to the resistance. In this case, the incandescent bulb with 264.5 ohms of resistance will draw 0.43 amps of current when connected to a 115-volt circuit.

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Ballast resistance measurement

When measuring the resistance of a ballast, it's crucial to ensure the power source is de-energized. This is to prevent electrical shocks and short circuits during the measurement process.

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Circuit breaker function

A circuit breaker is designed to protect electrical equipment from overloads and current surges. When the current exceeds a predetermined limit, the circuit breaker trips, interrupting the flow of electricity to prevent damage to the equipment.

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Safe de-energization of a duplex wire

A live duplex wire should be de-energized using a proper tool: a diagonal cutter. Cutting one wire at a time with a diagonal cutter ensures a controlled and safe de-energization process.

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Power supply for a neutral system

A wye-connected transformer is required to provide a neutral point in a wye-connected electrical system. This neutral point allows for a single-phase four-wire system, offering balanced voltage and current distribution.

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Locked rotor condition

If the rotor of a motor is forced to stop while running, the motor will encounter high current and potentially burn out. This is because the motor windings cannot handle the high current generated by the locked rotor condition.

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Study Notes

National Assessment for Electrical Installation and Maintenance NC III - Written Test

  • Qualification: Electrical Installation and Maintenance NC III
  • Units of Competency Covered:
    • Perform installation of data measurement and control system on electrical and auxiliary equipment.
    • Install, assemble, test, and maintain motor control systems.
  • Instructions:
    • Read directions carefully.
    • Write answers on the answer sheet provided.
    • Scratch work can be done on the back of the answer sheet.
    • Complete the test within one hour (hand in sooner if finished early).
    • Use capital letters only.

Example 1: Multiple Choice

  • Question: To ensure safety of tools and equipment, where should they be stored?
  • Options:
    • Production office
    • Locker room
    • Tool room
    • Electrical room
  • Correct Answer: Tool room (C)

Test Questions - Page 4

  • Question 1: How does inductance impact the relationship between current and voltage in a circuit?

    • Correct Answer: The current lags the voltage (D)

  • Question 2: How should oil spills on concrete floors be handled?

    • Correct Answer: Spreading sand and sweeping (D)

  • Question 3: Why is grounding the frame of a portable electric hand tool important?

    • Correct Answer: To prevent electric shock (A)

  • Question 4: What's the correct angle for positioning a ladder for safety?

    • Correct Answer: 30° from the vertical (A)

  • Question 5: What material typically covers under-floor raceways?

    • Correct Answer: Linoleum (B)

Test Questions - Page 5

  • Question 6: What is the maximum allowable combined cross-sectional area for conductors or cables?

    • Correct Answer: 50% of the interior cross-sectional area of the cell or header (D)

  • Question 7: How much current will a 115-volt, 264.5-ohm incandescent bulb draw?

    • Correct Answer: 0.43 amps (B)

  • Question 8: When measuring ballast resistance, what's the state of the source?

    • Correct Answer: De-energized (B)

  • Question 9: What does a circuit breaker protect electrical equipment from?

    • Correct Answer: Current surges and overloads (B)

  • Question 10: How to safely de-energize a live duplex wire?

    • Correct Answer: One-by-one using diagonal cutter (D)

Test Questions - Page 6

  • Question 11: What kind of power supply is used with a system neutral?

    • Correct Answer: Single-phase four-wire (D)

  • Question 12: What happens if a motor's rotor is locked?

    • Correct Answer: Encounters high current & potentially burns (B)

  • Question 13: A 1HP, 230V, 1-phase, 60Hz motor supplied with 110VAC will:

    • Correct Answer: Rotate slowly, encounter high current, and may burn (B)

  • Question 14: Which switch is commonly used for starting a motor?

    • Correct Answer: Single pole switch (D)

  • Question 15: What are the typical voltage ratings for a 6-lead motor?

    • Correct Answer: All of the above (D)

Test Questions - Page 7

  • Question 16: How do circuit breakers handle electrical faults?

    • Correct Answer: Tripping capacity (A)

  • Question 17: What's the proper procedure before energizing the main circuit?

    • Correct Answer: All loads and branch circuit breakers are de-energized (D)

  • Question 18: A 3-phase motor burning due to single phasing requires what protective device?

    • Correct Answer: Overload relay (A)

  • Question 19: What protective device prevents accidental motor reversal?

    • Correct Answer: Phase sequence relay (A)

  • Question 20: What is the minimum required conductor capacity for a motor with a 40-Ampere full load current?

    • Correct Answer: 125% of the full load current (A)

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Electrical Installation and Maintenance NC III Written Test PDF

Description

This quiz assesses your knowledge in Electrical Installation and Maintenance NC III, covering installation, testing, and maintenance of electrical systems. Answer multiple-choice questions based on the competencies outlined in the qualification. Prepare to demonstrate your understanding of inductance, motor control systems, and safe tool storage.

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