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What is the relationship between the Code letter and starting current?

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The higher the Code letter, the higher t...

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What are the rules that govern air-conditioning and refrigerating equipment disconnect means?

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Be careful about locating the disconnect...

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When referring to motor controllers in the United States , we prefer to use the term instead of coordination because coordination has a different meaning.


A) protection
B) isolation
C) breaking
D) service

E) B) and C)
F) A) and B)

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is the most common cause of motor failure.


A) An open contact
B) Unbalanced voltage
C) Single phasing
D) Wrong service factor

E) B) and D)
F) B) and C)

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For every degree Celsius rise above the motor's rated temperature, the motor's insulation life is cut in half.


A) 5
B) 10
C) 32
D) 50

E) All of the above
F) B) and C)

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fuses are designed to withstand motor-starting inrush currents and will not open needlessly.


A) Ordinary
B) Branch-circuit
C) Dual-element, time-delay
D) Nontime-delay

E) None of the above
F) A) and D)

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means the difference between motor winding temperature and the ambient temperature.


A) Operating temperature
B) Service factor
C) Overcurrent
D) Temperature rise

E) A) and D)
F) C) and D)

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NEC 430.24 requires that the conductors supplying several motors, or a motor(s) and other load(s) , shall have an ampacity not less than percent of the full-load current rating of the highest rated motor.


A) 75
B) 100
C) 125
D) 150

E) C) and D)
F) None of the above

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What are some possible causes of unbalanced voltage?

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The following may be the reason behind u...

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Motors marked with Insulation Class B are suitable for use in ambient temperatures of up to degrees Celsius.


A) 105
B) 130
C) 155
D) 180

E) B) and D)
F) C) and D)

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In three-phase motors, each phase is degrees out of phase (symmetrical) with the other phases.


A) 60
B) 90
C) 120
D) 360

E) A) and D)
F) C) and D)

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What are some reasons behind the failure of motors?

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Motor failures happen for many reasons.Abuse, lack of oil, bad bearings, insulation failure (end-of- normal life, oil, moisture), dirt or other foreign material (reduced ventilation), single-phasing, unbalanced voltage, and jammed V-belts are a few of the conditions that can cause a motor to draw more than normal current.Too much current results in the generation of too much heat within the windings of the motor.For every 10 degrees Celsius above the maximum temperature rating of the motor, the expected life of the motor is reduced by 50%.This is sometimes referred to as the "half­life rule."

A motor may be loaded continuously up to the horsepower obtained by multiplying the rated horsepower by the ____.


A) switch rating
B) ambient temperature
C) service factor
D) insulation rating

E) B) and C)
F) All of the above

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What is the minimum starting current for a 240-volt, 3-phase, Code letter J, 7-1/2-horsepower motor?


A) 114 amperes
B) 128 amperes
C) 132 amperes
D) 144 amperes

E) C) and D)
F) A) and B)

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An appliance is rated at 4500 volt-ampere, 240 volts.What is the maximum size fuse permitted?


A) 20-ampere
B) 30-ampere
C) 40-ampere
D) 50-ampere

E) A) and B)
F) A) and C)

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Describe Type 2 short-circuit protection.

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Type 2 short-circuit protection means th...

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The reason the Code uses the term instead of motor is that, in many instances, the motor is inside an enclosure and is out of sight until an access panel is removed.


A) motor location
B) lock-out
C) start-stop
D) motor vicinity

E) None of the above
F) B) and C)

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A

For most applications, the motor circuit switch for a motor must be .


A) general-use
B) isolating
C) overcurrent
D) horsepower rated

E) None of the above
F) C) and D)

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Color selection for ungrounded "hot" conductors can be just about any solid color except green, white, gray, or any color conductor (except ) that has three continuous white stripes.


A) black
B) blue
C) red
D) green

E) B) and D)
F) A) and B)

Correct Answer

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NEMA rated motors are designed to operate at plus/minus percent of their nameplate rated voltage.


A) 10
B) 20
C) 30
D) 40

E) A) and C)
F) A) and B)

Correct Answer

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A

Showing 1 - 20 of 20

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