Ch 4

Question 1

If there is a neutral-to-case connection on the load side of f the GFCI protection device, the sensors detect the imbalance of the current returning on the _______ and prevents the GFCI device from being turned on

Answer 1

ECG or Equipment Grounding Conductor

Question 2

A current-limiting type fuse is a fuse designed for operations relating to only what?

Answer 2

Short circuits

Question 3

The electrical connection between any two conductors of the electrical system from line-to-line- or from line-to-neutral is called:

Answer 3

Short Circuit

Question 4

What are the two ways in which power is transferred from the utility distribution transformer?

Answer 4

Overhead service drop : underground service lateral

Question 5

The NEC requires a listed AFCI-protection device to be installed to protect the branch-circuit wiring for ______

Answer 5

Dwelling unit bedrooms

Question 6

A GFCI operates on the principle of monitoring the imbalance of ____ between the circuits _____ and _____

Answer 6

Current : Ungrounded : Neutral

Question 7

The opening time for an overcurrent protection device is _____ proportional to the ______ of the current

Answer 7

Inversely : Magnitude

Question 8

A fault must quickly be removed by doing what?

Answer 8

Opening the circuit’s overcurrent protection device

Question 9

Would you use a GFCI or AFCI to clear a Ground Fault Parallel Arc?

Answer 9

Either

Question 10

What happens to a fuse when a sustained overload occurs?

Answer 10

A portion of the element is overheated and breaks, which prevents current from going through the fuse.

Question 11

Electromagnetic circuit breakers open on the principle of ________ and _______

Answer 11

Thermal Energy and Electromagnetism

Question 12

Ground-fault protection of equipment is a system intended to provide protection of equipment from damaging ground-fault currents by _____ all ungrounded conductors of the faulted circuit.

Answer 12

Opening

Question 13

What kinds of protection do Instantaneous breakers offer?

Answer 13

Short circuit and ground fault. Not overload

Question 14

This type of circuit breaker depends upon temperature rise in the sensing element for actuation. It has a predetermined calibration temperature.

Answer 14

Thermal Trip Element

Question 15

The purpose of overcurrent protection is to protect equipment and the conductors from what?

Answer 15

Dangerous temperatures

Question 16

What is a more dangerous arc fault, parallel or series?

Answer 16

Parallel

Question 17

Typically, when a GFCI protection device fails, the switching contacts remain closed and the device will continue to provide power _____ GFCI protection

Answer 17

Without

Question 18

What does “AIR” stand for?

Answer 18

Ampere Interrupting Rating

Question 19

The most effective way to reduce conductor voltage drop and power loss is to:

Answer 19

Lower the current flowing through the conductors by increasing the circuit voltage

Question 20

What are the two ways parallel arcing faults occur?

Answer 20

Short circuit or ground fault

Question 21

Typically, circuit breakers and fuses are designed to open or clear short-circuit and ground-circuit fault current in how many cycles?

Answer 21

Less than 1

Question 22

The electrical connection between any ungrounded conductors of the electrical system and any non-current-carrying metal object is called:

Answer 22

Ground Fault

Question 23

Typically, a steam turbine is directly connected to an electrical generator, which produces _______ kV, three-phase power

Answer 23

13.80

Question 24

What are the two most common types of overcurrent protection?

Answer 24

Fuses and Circuit Breakers

Question 25

A series arc-fault current is ____ limited; the arc's current cannot be greater than the load current the conductor serves.

Answer 25

Load

Question 26

What temperature do electric arcs operate at?

Answer 26

Between 5,000 and 15,000 F

Question 27

Conductor power losses are directly proportional to the length of the conductor and the ______ of the current

Answer 27

Square

Question 28

Various distribution feeders transfer the primary distribution voltage from step-down substations to ________ ________

Answer 28

Distribution transformers

Question 29

Metal parts of premises wiring are bonded to a low-impedance path designed and intended to carry fault current from _______ to _______

Answer 29

The point of a line-case fault on a wiring system : the neutral conductor at the electrical supply source

Question 30

This type of breaker operates on the principle that as the current increases, the time it takes for the device to open decreases

Answer 30

Inverse time breaker

Question 31

Step-down substations reduce the voltage from the high-voltage transmission lines to 34.50 kV, 13.80 kV, or sometimes as low as 4160V. This reduced voltage is knows as ________

Answer 31

Primary distribution voltage

Question 32

Thermal circuit breakers depend on ________ _______ in the sensing element for actuation.

Answer 32

Temperature rise

Question 33

Electrical connection between any two conductors of the electrical system from line-to-line or line-to-neutral

Answer 33

Short Circuit

Question 34

The magnetic time-delay circuit breaker operates under which principle and how does that work?

Answer 34

Solenoid Principle. A movable core held with a spring, in a tube, is moved by the magnetic field caused by a short circuit or ground fault.

Question 35

A condition where equipment or conductors carry current in excess of their rated ampacity is called:

Answer 35

Overload

Question 36

The most economical way to transfer electrical power over long distances is with ______ ________

Answer 36

High voltage

Question 37

Is short-circuit current higher at the utility transformer or the branch-circuit load?

Answer 37

Utility transformer

Question 38

A ground fault parallel arc can only occur when a ___ path is present.

Answer 38

Ground

Question 39

An AFCI-protection device protects again arcing faults by recognizing the characteristics unique to an arcing fault and by functioning to _____ the circuit when a parallel arc fault is detected

Answer 39

de-energize

Question 40

The current flow in a short-circuit type arc is limited by the system _____ and the impedance of the arcing fault itself.

Answer 40

Impedance

Question 41

What are two ways to solve the problem of excessive available fault current?

Answer 41

1) Install equipment with a higher short-circuit rating | 2) Install a fast-clearing fuse to protect components in the circuit.

Question 42

Electrons leaving a power supply are always trying to go where?

Answer 42

Back to the power supply, not to Earth

Question 43

Overcurrent protection devices such as circuit breakers and fuses are intended to ________ the circuit

Answer 43

Interupt

Question 44

Electrical connection between any ungrounded conductors of the electrical system and any non-current-carrying metal object

Answer 44

Ground Fault

Question 45

Why does the electric utility ground the primary and secondary neutral in multiple locations?

Answer 45

To create a parallel path as to reduce the impedance of the return neutral current path

Question 46

The voltage drop of a conductor is directly proportional to the _____ of the conductor because conductor ______ is directly proportional to the conductor lenght

Answer 46

Length : resistance

Question 47

What might cause a short-circuit parallel arc?

Answer 47

Damage to the wire's insulation

Question 48

What do you call the element electrically connected to the end blades on a fuse?

Answer 48

Ferrules

Question 49

Neutral current should only flow on the ______, not on the metal parts of the electrical installation

Answer 49

Neutral conductor

Question 50

Adjustable trip breakers permit the ____ _____ to be adjusted

Answer 50

Thermal Trip

Question 51

Condition where equipment or conductors carry current in excess of their rated ampacity

Answer 51

Overload

Question 52

Electrical equipment must have a ______ _____ current rating that permits the circuit overcurrent protection device to clear a short circuit or ground fault

Answer 52

Short-circuit

Question 53

To remove dangerous touch voltage on metal parts from a ground fault, the fault current path must have sufficiently low _______ to allow the fault current to quickly rise to facilitate the opening of the branch circuit overcurrent protection device

Answer 53

Impedance

Question 54

This type of breaker operates on the principle of electromagnetism only and is used for very large motors and sometimes called motor-circuit protectors

Answer 54

Instantaneous trip breakers

Question 55

An inverse time breaker provides overcurrent for what kinds of faults?

Answer 55

Overload : Short Circuit : Ground Fault

Question 56

(T/F) At the step-up substation, the 13.80 kV generated voltage is transformed to 69 kV, 500 kV or even higher.

Answer 56

True

Question 57

(T/F) f you touch the neutral and ungrounded conductors at the same time the GFCI protection device will turn turn on.

Answer 57

False

Question 58

Distribution transformers further reduce the primary distribution voltage from 34.50 kV or 13.80 kV to 240V or 480V, three-phase for the average commercial or small industrial customer. What is that called?

Answer 58

Secondary distribution voltage

Question 59

Electric power is typically generated and transmitted across _____ ______ lines to the electrical substation

Answer 59

Long transmission

Question 60

The electrical system begins at a generating plant that converts energy from ______, _______, or _______, power to ____, which turns the turbine of an electric generator.

Answer 60

Coal : Oil : Nuclear : Steam

Question 61

What is the purpose of grounding and bonding metal parts of the electric utility equipment to the neutral conductor?

Answer 61

To provide a low-impedance parallel path for the purpose of clearing a line-to-case ground fault

Question 62

What is the purpose of a GFCI?

Answer 62

To protect persons agains electrical shock