Deck 7: Motor and Appliance Circuits

Question 1

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

Answer 1

A

Question 2

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

Answer 2

B

Question 3

____ is the most common cause of motor failure.

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

Answer 3

B

Question 4

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

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

Question 5

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

Question 6

What are some possible causes of unbalanced voltage?

Question 7

Describe Type 2 short-circuit protection.

Question 8

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

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

Question 9

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

Question 10

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

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

Question 11

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

Question 12

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

Question 13

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

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

Question 14

____ 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

Question 15

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

Question 16

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

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

Question 17

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

Question 18

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

Question 19

​What are some causes of motor failure?

Question 20

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