Elap 2A Final Flashcards
Equipment designed to open circuits under fault conditions shall have an interrupting rating not less than the available voltage and circuit current at the line side of the equipment.
True
Equipment that is required to be readily accessible shall be capable of being reached quickly without the use of tools, with an exception for ___.
Keys
A conductors ____ is the amount of amperes it can carry continuously without exceeding its temperature rating.
Ampacity
The two fold purpose of the NEC is to protect ___ from the hazards associated with the use of electricity
Persons and property
Most voltages referenced in the NEC are ___ voltages
Nominal
Interpretations and approval of equipment are granted by the ___
AHJ
The AHJ can permit alternate ___ for installation.
Methods
Although installed in conformance with the NEC, all electrical installations may not be adequate for ___ expansion of electrical use.
Future
The NEC is not intended to be used as a ___ specification
Design
___ conductors are conductors not encased in a material recognized by the NEC as electrical insulation
Covered
Connectors, couplings, locknuts, and bushings are electrical ___
Fittings
___ means recognized as suitable for the use, purpose, ext.
Identified
Equipment that as been ___ is published in a directory by the testing lab certifying it is acceptable to the AHJ.
Listed
The purpose of a raceway is to help protect conductors from physical ___
Damage
The NEC requires that all electric equipment and conductors be ___ to be deemed acceptable to the AHJ
Approved
All unused openings other than those intended for the operation of equipment are required to be effectively ___ to afford equivalent protection.
Closed
Terminals for more than one conductor shall be ___
Identified
One of the ___ shall be readily accessible as required by the NEC.
Disconnecting means
___ conductors are the conductors form the service point to the service disconnecting means.
Service
___ conductors are all circuit conductors between the service equipment and the final branch circuit overcorrect device.
Feeder
The ___ is the portion of the electrical circuit between the last overcorrect device and the outlets or utilization equipment
Branch Circuit
A ___ load is a load where the waveform of the steady state current does not follow the wave shape of the applied voltage
Nonlinear
Branch circuits with not over 120 V between conductors are permitted to supply auxiliary equipment of electric discharge lamps
True
A GFCI receptacle or circuit breaker is set to trip at 10 mA
False
Receptacle outlets installed in a dwelling for specific appliances shall be located within ___’ of the appliance
6
At least one receptacle outlet shall be installed in ___’ or longer hallways of dwelling units.
10
___ is the ratio of the maximum demand of a system, or part of a system, to the total connected load of a system or the part of the system under consideration
Demand Factor
Branch circuit EGCs smaller than 4 AWG shall have a continuous outer finish that is either green or green with one or more ___ stripes
Yellow
All conductors of a ___ branch circuit shall originate from the same panelboard
Multiwire
A current flow of ___ mA will most likely cause the heart to stop pumping
100
A ___ is the amount of electricity required at a given time
Demand
Each single or multiple receptacle on a single strap is calculated at ___ VA.
180
Demand factors may be applied to ___ of the six loads of the standard calculation.
4
Four or more appliances that are fastened in place in a one family dwelling are calculated at ___ of the total loader all four appliances.
75%
The total load for household clothes dryers is calculated at ___ VA or the nameplate rating, whichever is higher (standard calculation)
5000
___ loads are loads that are not on the same time
Noncoincidental
The ___ load is the maximum unbalance between any of the ungrounded conductors and the grounded conductor
Feeder Neutral
For 1 systems, the formula ___ is used to determine minimum ampacity of the ungrounded conductors
I = VA/A
Heating or A/C loads are calculated at ___ of the nameplate rating and the largest load is used (standard calculation)
100%
After the minimum ampacity of the dwelling service has been calculated, Table ___ and 310.15(B)(7)(1) are used to determine the size of service entrance conductors
310.15(B)(16)
The demand had for household electric ranges rated in excess of ___ kW is calculated per Table 220.55 (Standard Calculation)
1-3/4
Feeders for several motors are calculated using the sum of the FLC tables of all motors plus ___% of the largest motor
25%
Less than four separately controlled electric space heating units in a dwelling unit are calculated at ___ % of their nameplate ratings (optional calculation)
65%
The ___ is the electrical supply, in the form of conductors and equipment, that provides electrical power to the building or structure.
Service
The ___ is the overhead conductors between the service point and the utility electric supply system
Service Drop
The __ is the underground service conductors that connect the utilities electrical distribution system and the service point.
Service Lateral
GFPE is designed to operate at settings not greater than 200 A
False
___ conductors are the conductors that extend from the service disconnecting means to the service point where the service point is located at the connections made at the service drip loop.
Overhead Service Entrance
Direct buried conductors emerging form the ground shall be protected from physical damage up to a point which is at least ___’ above finish grade
8
SE cable shall be supported at intervals not exceeding ___” and within ___” of every service head, gooseneck, or point of connection to a raceway or enclosure.
30; 12
Plug fuses have a voltage rating of ___ V between conductors in most applications
125
Insulated conductors installed in wet locations shall be of a type ___ for the use
Listed
No conductor shall be installed in such a manner that the operating temperature of its ___ is exceeded
Insulation
Flug fuses of 15A and lower are identified by ___ configuration of the fuse window
Hexagonal
Cartridge fuses with no markings are rated for ___ A
10,000
Circuit breakers that are not marked have an interrupting rating of ___ A
5,000
___ conditions include installations where the conductors are exposed to oils, greases, vapors, etc. that break down the integrity of the conductors insulation
Corrosive
Ampacity of feeder taps not over 25’ shall not be less than 1/3 of the rating of the overcorrect protective device protecting the ___ conductors
Feeder
In general, fuses and circuit breakers shall not be connected in ___.
Parallel
A ___ is a circuit breaker with an intentional delay between the time when the fault or overload is sensed and the time when the CB operates
ITCB
The next ___ standard size OCPD of 800 A or less is permitted to be used where the OCPD does not correspond to a standard size
Higher
A ___ is any current in excess of that for which the conductor or equipment is rated
Overcurrent
Type S fuses are designed for circuits not exceeding 100 V
False
Locations can be classified as either dry, ___ or wet
Damp
The greeks were the first to discover electricity about ___ years ago.
2500
A semiconductor contains ___ valence electrons
4
Direct current is described as ___
unidirectional
Alternating current is described as ___
bidirectional
One coulomb per second is equal to one ___
ampere
The amount of potential necessary to cause one coulomb to product to produce one joule of work is a ___
Volt
The unit of resistance to current flow is the ___
ohm
In a DC circuit, the current is directly proportional to voltage and inversely proportional to resistance is know as ___
Ohms Law
The force of electrostatic attraction or repulsion is directly proportional to the product of the two charges and inversely proportional to the square of the distance between them?
Coulombs Law
The amount of electrical power being used in a circuit is measured in ___
Watts
What is another term for electromotive force?
Voltage
A voltmeter has a very ___ resistance connected in series with the meter movement
High
A test meter that uses a scale and pointer to indicate values is a ___ meter
Analog
An ammeter is connected in ___ with the load to permit the load to limit current flow
Series
What meter is designed to be connected directly across the power source?
Voltmeter
What meter measures an amount of voltage during a period of time and produces a two dimensional image?
Oscilloscope
The function that is equal to the adjacent divided by the hypotenuse is the ___
cosine
What memory aid will help you remember the trigonometric function relationships?
Oscar had a heap of apples
The function that is equal to the opposite divided by the hypotenuse is the ___
Sine
A line that indicates both magnitude and direction is a ___
Vector
A voltaic cell is constructed of two unlike metals and a(n) _____, alkaline, or salt solution.
Acid
Several cells connected together that produce voltage are called a _____.
Battery
The LeClanché cell is also known as a(n) _____ cell.
Carbon-zinc
Thermocouples produce voltage because of the action of two dissimilar metals. The voltage produced depends on the type of metals used and the _____ difference between the junction and the open ends.
Temperature
The amount of energy a cell can deliver is called its _____ capacity.
Current
The no-load voltage of a cell is greater than the normal load voltage because of the internal _____ of the cell.
Resistance
Piezoelectricity refers to electricity produced by some materials when they are subjected to _____.
Pressure
The amount of voltage produced by an individual _____ is determined by the materials from which it is made.
Cell
To perform a load test on a lead-acid battery, the amount of test current should be _____ times the ampere-hour capacity.
Three
What type of cell can be recharged?
Secondary
What type of cell cannot be recharged?
Primary
In 1800, Alessandro Volta was experimenting with producing electricity. He called his battery _____.
Voltaic pile
The time required for current in an inductor to reach its full Ohm’s law value is called the _____ time constant.
R-L
Losses in the core of iron core inductors include _____ and _____ losses.
Eddy Current; Hysteresis
What is one device used for spike suppression in either direct or alternating current circuits?
Metal Oxide Varistor
An induced voltage opposes the motion that causes it according to _____.
Lenz’s Law
Exponential curves are always divided into _____ time constants.
Five
During the period of time known as the first time constant of an exponential curve, the current will rise to about _____ percent of its full value.
63.2
A way of determining the relationships of the motion of the conductor, the magnetic field direction, and the direction of the induced current is by using the _____.
Left-Hand Generator Rule
When using the left-hand generator rule, the center finger points to the direction of _____.
Current
What is the unit of measurement for inductance?
Henry (H)
When a conductor cuts magnetic lines of force, a voltage is induced into the conductor. This principle is called _____.
Electromagnetic Induction
The direction of induced current can be determined by using _____’s left-hand generator rule.
Fleming
When a closed loop of wire cuts through magnetic flux lines, a current is induced into the loop. The current in the loop sets up a magnetic field that is in opposition to the original magnetic flux. This is essentially _____.
Lenz’s Law
If a voltage is being induced into a conductor by electromagnetic induction, reversing the direction of motion of the conductor will _____.
Reverse the polarity of the induced voltage
When using the left-hand generator rule, the thumb points to the direction of _____.
Thrust
What is the unit of measure for the power delivered to the load in a DC circuit?
Watts
In a DC circuit, the product of volts times the amperes is called the _____ power.
True
What type of load contains pure resistance?
Resistive
The maximum point of a waveform is called the _____.
Peak
If an AC waveform is rectified and converted into DC, the voltage value that results is the _____ value.
Average
Rotating machines normally produce a waveform called a _____ wave.
Sine
What type of AC waveform features voltage rising at a constant rate with respect to time?
Linear
The number of cycles completed in one second is called a _____.
Frequency
When current rises and falls at the same rate as the voltage and reverses the direction of flow when the voltage reverses polarity, the current is said to be _____ with the voltage.
In Phase
A term used to indicate the same value as the RMS value is the _____ value.
Effective
When AC voltage is rectified and converted into DC, the resulting waveform is normally not pure, flat DC. The pulses that occur are called _____.
Ripples
The_____ effect occurs when AC induces eddy currents into the conductor, which cause the electrons to be repelled toward the outer surface of the conductor.
Skin
What is the most common of all AC waveforms?
Sine
The square root of the mean of the square of the instantaneous currents is known as the _____.
RMS
Each complete waveform of 360° is called a _____.
Cycle
The amplitude of a waveform is measured from _____.
Zero to the highest value obtained in either direction
A voltmeter has a very _____ resistance connected in series with the meter movement.
High
An ammeter is connected in _____ with the load to permit the load to limit current flow.
Series
In a right triangle, the two non-right angles are each formed by the hypotenuse and one of the other sides. From the perspective of the angle, the side that is not the hypotenuse is called the _____.
Adjacent Side
One method of adding two vectors that originate at the same point is the _____ method.
Parallelogram
The total current-limiting effect is called _____.
Impedance
The symbol for reactive power of an inductor is _____.
VARs
The unit of inductance is the _____.
Henry
Circuits are generally considered to contain _____ when any type of load that contains a coil is used.
Inductance
When a magnetic field continually changes magnitude and direction, a voltage is continually being induced in the coil. This voltage is called _____ voltage.
Induced
In a pure inductive circuit, current _____.
lags voltage by 90 degrees
The current-limiting property of an inductor is called _____.
Reactance
The waveform of the CEMF is _____ out-of-phase with the applied voltage.
180 degrees
Eddy currents are small independent currents induced within the conductor because of direct current.
False
A common practical use of induction is for _____.
Motors, Transformers, Generators
For ac circuits, the ac _____ of a conductor must be taken into consideration.
Eddy currents, skin effect, resistance
Conductor resistance is directly proportional to the conductor’s length and cross-sectional area.
False
Self-induced voltage is 180º out-of-phase with the _____. When the applied voltage is at its maximum in one direction, the induced voltage is at its maximum in the opposite direction.
Applied Voltage
In a purely inductive circuit, the CEMF waveform is _____ out-of-phase with the applied voltage waveform.
180 degrees
The magnitude of self-induced voltage within a winding is directly proportional to the current flow, the winding, and the frequency at which magnetic fields cut through the winding.
True
The expanding and collapsing magnetic field within the conductor induces a voltage in the conductors (CEMF) that repels the flowing electrons toward the surface of the conductor. This is called _____.
Skin Effect
The movement of electrons caused by an external magnetic field is called _____ current, and the associated potential that is established is called _____ voltage.
Induced
In dc circuits, the only property that affects current and voltage flow is _____.
Resistance
In a parallel circuit, the voltage across the resistor and the voltage across the inductor are _____.
In phase
In a parallel circuit, the current flow through the inductor will be _____.
90° out of phase with the voltage
In a pure capacitive circuit, the current _____ the applied voltage by _____.
leads; 90°
A capacitor is constructed by separating two metal conductors known as _____ with an insulating material known as a(n) _____.
plates; dielectric
A charge curve for a capacitor is divided into _____ time constants
Five
Polarized capacitors _____.
must be used with DC only
The JAN standard is used to mark a capacitor intended for _____.
Military
Polarized capacitors are also known as _____ capacitors.
Electrolytic
Nonpolarized capacitors _____.
Can by used with either AC or DC
When a capacitor is connected in a circuit with a resistor, the amount of time needed to charge the capacitor is called the _____.
RC time constant
The capacitive reactance of a capacitor is _____ proportional to frequency.
Inversely
When the voltage and current have _____ polarities in a pure capacitive circuit, the capacitor is discharging and the energy is returned to the circuit.
Opposite
The material between a capacitor’s plates is rated by a value called the _____.
Dielectric constant
The voltage rating of a capacitor _____.
should never be exceeded
In a capacitor, the voltage difference between the plates controls the _____.
amount of dielectric stress
Of the different power values in an RL circuit, which one is known as quadrature power?
VARs
Dividing a circuit’s total applied voltage by the total impedance results in the total _____.
Current
Of the different power values in an RL circuit, which one is known as wattless power?
VARs
Power factor (PF) is the ratio of the _____ power to the _____ power.
True; apparent
In a series circuit, the total _____ is equal to the sum of the individual resistors.
Resistance
In a series RC circuit, apparent power can be calculated by _____.
ET × I
Of the different power values in an RC circuit, which is known as apparent power?
VA
If the voltage is behind the current in a RLC series circuit, the power factor is referred to as _____.
Leading
In an RLC series circuit, the ratio of resistance, inductance, and capacitance determines how much the applied _____ leads or lags the circuit current.
Voltage
If the voltage in a RLC series circuit is ahead of the current, the power factor is referred to as _____.
Lagging
If the current leads the voltage in a RLC series circuit, the power factor is referred to as _____.
Leading
In a RLC series circuit, the point at which XL and XC are equal is called _____.
Resonance
Because inductive reactance and capacitive reactance are _____ out of phase with each other, they subtract from each other in an AC circuit.
180°
If a RLC series circuit contains more capacitive VARs than inductive VARs, then the circuit has a _____ power factor.
Leading
In a RLC series circuit, _____ is the same through all components and the _____ are out of phase.
Current; Voltages
To correct the power factor to 100 percent an equal amount of capacitive VARs would be connected in _____ with the motor.
Parallel
If the power factor is corrected exactly so that the circuit is purely resistive, the power factor has a value of _____.
Unity
In an RLC parallel circuit, the _____ is the same through all components and the _____ are out of phase.
Voltage; Currents
If a RLC parallel circuit contains more inductive VARs than capacitive VARs, the circuit has a _____ power factor.
Lagging
A nonsinusoidal waveform is created when _____ loads distort the voltage and current sine wave.
Nonlinear
The movement of electrons themselves does not produce any useful work. It’s the effects that the moving electrons have on the loads they flow through that are important.
True
The effective value is equal to the peak value _____.
times 0.707
Effective ac voltage or effective ac current is the equivalent value of dc voltage or dc current that would produce the same amount of heat in a resistor.
True
The number of complete waveforms in one second is called the frequency. Frequency is expressed as _____ or cycles per second.
Hertz
The term “phase” is used to indicate the time or degree relationship between two waveforms, such as voltage-to-current or voltage-to-voltage.
True
Output voltage of a generator depends upon the _____.
Number of turns of wire, strength of the magnetic field, speed at which the coil rotates
The movement of electrons themselves does not produce any useful work. It’s the effects that the moving electrons have on the loads they flow through that are important.
True
n ac generators that produce large quantities of electricity, the conductor coils are stationary and the magnetic field revolves within the coils.
True
_____ describes the steps necessary to determine the effective voltage or current value.
“Root-mean-square”
The _____ wave is a waveform that is symmetrical with positive above and negative below the zero reference level.
Sine
A capacitor is a device that resists changes in current. Because a capacitor introduces reactance to the circuit, it shifts the current waveform to _____.
lead the applied voltage by 90º
If a capacitor is overcharged, the electrons from the negative plate could be pulled through the insulation to the positive plate. The capacitor is said to have _____.
Shorted
A half-wave rectifier can be used to convert ac voltage into dc voltage to continuously charge a capacitor.
False
To discharge a capacitor, all that is required is a(n) _____ path between the terminals of the capacitor. The free electrons on the negative plate then flow through the external circuit to the positive plate.
Conductive
_____ is a property of an electrical circuit that enables it to store electrical energy by means of an electric field and to release this energy at a later time.
Capacitance
The waveform of the CEMF is _____ out-of-phase with the applied voltage.
180°
Conductor resistance is directly proportional to the conductor’s length and cross-sectional area.
False
The magnitude of self-induced voltage within a winding is directly proportional to the current flow, the winding, and the frequency at which magnetic fields cut through the winding.
True
How many 20A, 120V circuits are required for forty-two, 300W incandescent luminaires (noncontinuous load)?
6 Circuits
What size transformer is required for a 100A, 240V, single-phase noncontinuous load (unity power factor)?
25 kVA
Efficiency describes how much input energy is used for its intended purpose.
True
When sizing circuits or equipment, always size the circuit components and transformers according to the apparent power (VA), not the true power (W).
True
To determine the true power consumed by a dc circuit, multiply the volts by the amperes.
True
Power factor is a measurement of how far the current is out-of-phase with the voltage.
True
Because apparent power (VA) is greater than true power (W), more loads can be placed on a circuit, so fewer circuits and panels, and smaller transformers might be required.
False
How many 20A, 120V circuits are required for forty-two, 300W luminaires (assume this is a noncontinuous inductive load) that have a power factor of 85 percent?
7 Circuits
If you measure voltage and current in an inductive or capacitive circuit and then multiply them together, you obtain the circuit’s _____.
Apparent power
Energy is stored in the electromagnetic field of an inductor and the electric field of a capacitor.
True
A transformer that has one winding, which is used for both the primary and secondary, is called a(n) _____.
autotransformer
Any transformer flux that does not follow the core and escapes into the surrounding air is called _____.
flux leakage
Most transformer cores are assembled from many thin sheets of metal. This type of construction is called _____.
laminated
A transformer in which the secondary voltage is more than the primary voltage is called a(n) _____ transformer.
step-up
A tape-wound core is also called a(n) _____ core.
toroid
The power input winding of a transformer is called the _____ winding.
primary
What type of core is often found on high-voltage distribution transformers?
H-Type
What is a magnetically operated device that can change values of voltage, current, and impedance without changing frequency?
A transformer
A transformer in which the primary and secondary are physically separated and not connected by a conductor is called a(n) _____ transformer.
isolation
In a transformer, the turns of primary wire compared to the turns of secondary wire is called the _____ ratio.
turns
A transformer supplying a house with 240/120 V has a secondary which is center tapped. The conductor connected to the center is called the _____ conductor.
neutral
The industrial use transformer that normally has 240 V or 480 V primary and a 120 V secondary is called a(n) _____ transformer.
control
A transformer has a 240 V primary and a 120 V secondary. With a 30 ohm load connected, what is the primary volt-amps?
480
The output winding of a transformer is called the _____ winding.
secondary
If three-phase transformation is needed and a three-phase transformer of the proper size and turns ratio is not available, three single-phase transformers can be connected to form a _____.
three phase bank
For installations that will have both three-phase and single phase loads on a three-phase transformer, the utility company often provides a(n) _____ three-phase transformer.
open delta with one transformer center tapped
When using an open delta with a center tapped transformer, one wire is the high leg. The high leg is the one that _____.
has the highest voltage
A wye-delta transformer has a primary voltage of 7200 V and a secondary voltage of 360 V. What is the turns ratio?
11.55:1
In an open delta with a center-tapped transformer, label the two ends of the center-tapped transformer as L2 and L3 and label the high leg as L1. The current flow in the neutral (center tap) is equal to _____.
AN = A1 + (A2 – A3)
The main power distribution system of a large industrial plant is generally shown using a(n) _____ diagram.
one-line
When connecting three transformers for three-phase use with a delta secondary, a voltage test should be done before closing the secondary. The correct voltage reading is _____.
zero volts
A delta-wye transformer has its _____ connected as a delta and its _____ connected as a wye.
primary; secondary
A wye-delta transformer has its _____ connected as a wye and its _____ connected as a delta.
primary; secondary
A wye-delta transformer has a primary line voltage of 7200 V and a secondary line voltage of 480 V. What is the turns ratio?
8.66:1
In three-phase transformer connections, the primary leads are labeled with the letter _____ and the secondary leads are labeled with the letter _____.
H; X
A wye-connected secondary has a phase voltage of 277.14 V. What is the line voltage?
480 V
An open delta connection is made using _____ single-phase transformers.
two
In an open delta with single-phase loads, the high leg must be identified by _____.
using orange wire; tagging
both A and B
What function is performed by dielectric oil?
It acts as an insulator
It prevents moisture formation
It provides cooling.
(All of the above)
The industrial use transformer that normally has 240 V or 480 V primary and a 120 V secondary is called a(n) _____ transformer.
Control
If three-phase transformation is needed and a three-phase transformer of the proper size and turns ratio is not available, three single-phase transformers can be connected to form a _____.
three-phase bank
