ch 2

Question 1

The ? in an electrical circuit is the electromotive force of the circuit.

Answer 1

voltage

Question 2

If the voltage of a DC circuit is 24 volts, and the resistance of the circuit is 10 ohms, what is the amount of current present in the circuit?

Answer 2

2.4 A

Question 3

For current to be present in electrical circuits, the circuit has to be ? .

Answer 3

complete

Question 4

Which of the following is included in the overall opposition to current in an AC circuit?

Answer 4

Inductive reactance

Capacitive reactance

Resistance

Question 5

If an electrical circuit is not complete, there will be no current in the circuit.

Answer 5

true

Question 6

The greater the resistance in a circuit, the ? the current present in the circuit.

Answer 6

lower

Question 7

If a 2,500-watt heater is supplied by a 480-volt circuit, how much current is present in the circuit?

Answer 7

5.2 A

Question 8

In a 60-cycle AC circuit, the voltage and current change amplitude and direction ? times per second.

Answer 8

120

Question 9

In its simplest form, a capacitor is two conductors separated by insulation.

Answer 9

true

Question 10

Kaufmann discovered that keeping the conductors of an AC circuit in close proximity to each other will keep the ? of the circuit low.

Answer 10

Impendance

Question 11

Current in an AC circuit will take which of the following paths while attempting to return to the source?

Answer 11

All conductive paths

Question 12

Equipment such as switchboards and panelboards installed in an electrical system must have adequate ? ratings to ensure that extensive damage to equipment will not result from a ground-fault or short-circuit condition.

Answer 12

short-circuit current

Question 13

Fuses and circuit breakers are required to be marked with all but which of the following ratings?

Answer 13

resistance

Question 14

The highest current at rated voltage that a device is identified to interrupt under standard test conditions best defines which of the following?

Answer 14

Interrupting rating

Question 15

The ? of an electrical system is the maximum current a system is capable of delivering at any point on the wiring installation.

Answer 15

available fault current

Question 16

An unintentional conducting connection between two ungrounded conductors of a circuit best describes which of the following?Short circuit

Answer 16

Short circuit

Question 17

The amount of available fault current in an AC circuit is reduced by the overall ? of the circuit.

Answer 17

impedance

Question 18

A(n) ? is defined as an unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non–current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.

Answer 18

ground fault

Question 19

Inverse time operation of overcurrent devices means that the ? the current, the ? the device will react to the ground fault or short circuit event.

Answer 19

higher / faster

Question 20

Failure of conductor insulation is not a cause of failures in high-voltage and low-voltage electrical wiring.

Answer 20

false

Question 21

Which of the following are common causes of conductor insulation failure?

Answer 21

Excessive voltage stress

Heat

Physical damage occurring during or after installation

Question 22

Section ? requires conductors and wiring installations to be free of short circuits and any grounding connections other than grounding connections specifically permitted in the NEC.

Answer 22

110.7

Question 23

According to the Insulated Cable Engineers Association (ICEA), the basic calculation for five-second insulated conductor current withstand ratings is as follows: For every ? area, an insulated conductor can safely carry one ampere for five seconds.

Answer 23

42.5

Question 24

Which of the following organizations developed the formulas to determine insulated and bare conductor current withstand ratings?

Answer 24

Insulated Cable Engineers Association (ICEA)

Question 25

Wire-type equipment grounding conductors must be capable of safely carrying high levels of available fault current for the duration of time it takes the overcurrent device for the circuit to open and clear the event.

Answer 25

true

Question 26

Which NEC table provides the minimum sizes for wire-type equipment grounding conductors?

Answer 26

250.122

Question 27

Which of the following test instruments is commonly used to determine the integrity of conductor insulation?

Answer 27

Megohmmeter

Question 28

The time-current curves provided by overcurrent device manufacturers provide the graphic information about the operating characteristics of fuses or circuit breakers represented in time depending on current levels.

Answer 28

true

Question 29

Which of the following symbols is not included in the formula for circuit impedance?

Answer 29

I

Question 30

Basic Ohm’s Law includes all but which of the following components?

Answer 30

time

Question 31

Wire-type equipment grounding conductors expressed in Table 250.122 of the NEC are approximately ? of the circuit conductor size.

Answer 31

25%

Question 32

A(n) ? is defined as an electrically conductive path from the point of a ground fault on a wiring system through normally non–current-carrying conductors, equipment, or the Earth to the electrical supply source.

Answer 32

ground-fault current path

Question 33

In the basic formula for impedance, XL represents the ? of the circuit.

Answer 33

inductive reactance

Question 34

If the voltage of a circuit is 240 and the resistance of the circuit is 30 ohms, how much current would be present in the circuit?

Answer 34

8 A

Question 35

Applying an overcurrent device (fuse or circuit breaker) within its marked interrupting rating will ensure that the overcurrent device can safely open the circuit in a ground fault condition.

Answer 35

true

Question 36

The highest current at rated voltage that a device is identified to interrupt under standard test conditions best defines which of the following?

Answer 36

Interrupting rating

Question 37

Using the time-current curve, determine the maximum 60-cycle clearing time for a 20-ampere, Squared D QO circuit breaker if a ground fault introduces 100 amperes in the circuit.

Answer 37

0.6 - 3 seconds