Final Test Flashcards
Which print shows the face views of the building or residence?
A) Elevation
B) Floor Plan
C) Plot Plan
D) Sectional
Elevation
Three coils with inductance of 2, 4, and 5 henries are connected in parallel. What is the total inductance of the circuit?
A) 358 mH
B) 950 mH
C) 1.05 H
D) 358 H
1.05 H
What would the current through a 150 mH coil connected across a 120-volt 60hz circuit be?
A) 1.06 A
B) 1.96 A
C) 2.12 A
D) 3.14 A
2.12 A
A transformer with more windings on the load side than on the line side is known as a ____ transformer.
A) Primary load
B) Secondary load
C) Step-down
D) Step-up
Step-up
Dwelling unit receptacle outlets serving kitchen wall countertop spaces shall be installed so that no point along the wall is more than ___ from a receptacle outlet.
A) 12”
B) 18”
C) 24”
D) 48”
24”
The ability of an inductor in a transformer to generate inductive reactance, which opposes changes in the current direction is called ___.
A) Impedance
B) Mutual Inductance
C) Reactance
D) Self-Inductance
Self-inductance
The symbol “L” is used in a drawing to identify ___.
A) Inductance
B) Inductive reactance
C) Unit of frequency
D) Unit of inductance
Inductance
A transformer has a turns ratio of 1:2. By applying 480 volts to the primary of this transformer, the secondary voltage will be ___.
A) 208 V
B) 240 V
C) 720 V
D) 960 V
960 V
(Circle with three parallel lines coming out the left side, and an “R” in the bottom right corner)
What does this symbol represent?
A) 125 V duplex outlet
B) 125 V special outlet
C) 250 V range outlet
D) 250 V recessed outlet
250 V range outlet
The capacitive reactance of a circuit is determined by the ___?
A) current and voltage
B) frequency and capacitance
C) impedance minus inductance
D) inductance minus resistance
frequency and capacitance
Where the NEC requires that one piece of equipment shall be “in-sight” from another piece of equipment, the specified distance shall be no more than ___ between equipment.
A) 25’
B) 50’
C) 75’
D) 100’
50’
A power transmission line has a current of 84 amps flowing through the conductor, and the conductor has a resistance of 11 ohms. What is the power flowing through the transmission line?
A) 642 W
B) 924 W
C) 10,164 W
D) 77,616 W
77,616 W
If the frequency is increased in a series RL circuit, the impedance will ___.
A) decrease
B) increase
C) increase proportionally to the current
D) remain the same
increase
Where connected to a branch circuit supplying two or more receptacles or outlets, receptacle ratings shall conform (illegible)
???
If a current of 30 amperes is measured on B phase of a wye-connected transformer, the current through the B winding will be
A) 15 A
B) 17.4 A
C) 30 A
D) 51.9 A
30 A
Xc = 1 / (2 * pi * f * C )
This formula is used to calculate ___.
A) Capacitive reactance
B) Impedance in a series LCR
C) Inductive reactance
D) Ohm’s Law
Capacitive reactance
Which item is not measured in ohms?
A) Capacitance
B) Impedance
C) Inductive Reactance
D) Resistance
Capacitance (farads)
If a 3-phase, single-voltage, wye-connected transformer is supplied by 4160 volts, the voltage across each winding will be ___.
A) 1680 V
B) 2405 V
C) 4160 V
D) 7197 V
2405 V
(source voltage over root 3)
___ is a direct result of an arc-blast event.
A) Fire
B) Heat
C) Light
D) Pressure
Pressure
Which item listed is classified as a fitting in reference to a wiring system?
A) Fuse
B) Lamp holder
C) Locknut
D) Receptacle
Receptacle
A 48-microfarad capacitor has a voltage drop of 30 volts across it in a 60hz AC circuit. How much current is flowing across it?
A) 542 mA
B) 625 mA
C) 540 A
D) 1670 A
542 mA
(Find capacitive reactance, then use that to find amps)
The load for household electric clothes dryers in a dwelling unit shall be ___ or the nameplate rating, whichever is higher.
A) 3500 W (VA)
B) 4000 W (VA)
C) 4500 W (VA)
D) 5000 W (VA)
5000 W (VA)
Where buildings exceed three stories or 50 feet in height, overhead lines shall be arranged, where practical, so that … either adjacent to the buildings or beggining not over ___ from them to facilitate the raising of ladders when necessary.
A) 3’ / 6’
B) 4’ / 8’
C) 6’ / 8’
D) 8’ / 10’
6’ / 8’
(Right triangle with sides of 10 and 12 units, and a hypotenuse of z units)
The length of side Z is ___.
A) 4.7
B) 15.6
C) 16.5
D) 17.8
15.6
(TRANSFORMER DIAGRAM | Primary with one leg of each coil going to A/B/C respectively and second leg of each coil tied together. Secondary in same configuration)
This transformer is connected ___.
A) primary delta - secondary delta
B) primary delta - secondary wye
C) primary wye - secondary delta
D) primary wye - secondary wye
primary wye - secondary wye
For show window loads calculated by the foot, a load of not less than ___ shall be included for each one foot of show window length.
A) 100 VA
B) 150 VA
C) 180 VA
D) 200 VA
200 VA
(Symbol of two vertical windings separated in the middle by two parallel vertical lines)
Identify this item.
A) Battery
B) Fuse
C) Thermostat
D) Transformer
Transformer
What is the total inductive reactance of a 60hz AC circuit with 50 ohms of resistance and 4 henries of inductance.
A) 480 ohms
B) 753.6 ohms
C) 1256 ohms
D) 1507.2 ohms
1507.2 ohms
(2 * pi * hz * L(henries))
Ignore resistance when finding reactance
Three capacitors of 2, 4, and 6 microfarads connected in series have a total capacitance of ___.
A) 1.09 uF
B) 4.52 uF
C) 8.62 uF
D) 12 uF
1.09 uf
(1/Ct = 1/C1 + 1/C2 + … + 1/Cn)
What is the correct GFCI level for a Class A device?
A) 1 mA
B) 5 mA
C) 22 mA
D) 30 mA
5 mA
Rigid PVC conduit larger than ___ trade size shall not be used.
A) 3”
B) 4”
C) 5”
D) 6”
6”
In general, each 1000 volt transformer, nominal, or less that has protection on the primary winding only, shall be protected … primary side, rated or set at not more than ___ of the rated primary current of the transformer.
A) 100%
B) 125%
C) 150%
D) 225%
125%
An electrical worker is reading a blueprint that uses a 1/8” to 1’ scale. The ruler measures 2 3/8” on the blueprint. What will that measurement be in the field?
A) 2’ 3”
B) 9’ 6”
C) 16’ 3”
D) 19’ 0”
19’ 0”
A set of drawings kept up to date as the installations are made and then given to the building owner after completion are called ___ drawings.
A) addendum
B) as-built
C) completion
D) final
as-built
In a 60hz single phase AC circuit, how many times does the voltage drop to 0 each second?
A) 0
B) 60
C) 120
D) 360
The term “kcmil” is used when referring to cables larger than ___.
A) 3/0
B) 4/0
C) 6/0
D) 8/0
4/0
Zr = Sqrt( R(squared) + (Xl - Xc)(squared) )
The formula represents___.
A) capacitive reactance
B) impedance in a series LCR circuit
C) inductive reactance
D) Ohm’s law
Impedance in a series LCR circuit
In a purely capacitive circuit, ___.
A) current and voltage are in-phase
B) current lags the applied voltage by 90 degrees
C) current leads voltage by 90 degrees
D) voltage and current are 180 degrees out of phase
current leads voltage by 90 degrees
A coil has an Xl of 150 ohms, and a resistor connected in series has a resistance of 100 ohms. What is the impedance of the circuit
A) 80 ohms
B) 125 ohms
C) 180 ohms
D) 250 ohms
180 ohms
(sqrt ( X squared + R squared )
The allowable ampacities listed in Table 310.05(B)(16) of the 2014/2017 NEC or in Table 310.16 are based on ambient temperatures not to exceed ___.
A) 75 F
B) 86 F
C) 92 F
D) 212 F
86 F
If a current is 20 amperes is measured on A phase of a delta-connected transformer, the current through the A phase winding is ___.
A) 11.6 A
B) 20 A
C) 34.6 A
D) 40 A
20 A
A transformer has a secondary voltage of 120 volts. The primary winding has 1800 turns and the secondary has 90 turns. What is the primary voltage?
A) 240 V
B) 480 V
C) 1800 V
D) 2400 V
2400 V
The thermal energy resulting in a burn to a worker in an arc-fault event is known as ___.
A) blast energy
B) high ambient energy
C) incident energy
D) kinetic energy
incident energy
What is the peak-to-peak voltage for an AC voltage source with a RMS value of 120 volts?
A) 84.84 V
B) 152.88 V
C) 169.68 V
D) 339.36 V
339.36 V
(Vrms = ( 1 / (2 * sqrt2) ) * Vpp
A series circuit contains four inductors with the following inductance values. 3.5 henries, 35 millihenries, 6 henries, and 250 millihenries. What is the total inductance for this circuit?
A) 0.9785 H
B) 9.1000 H
C) 9.7850 H
D) 96.000 H
9.7850 H
(inductance is simply added in series)
What is the standard unit of measurement for transformer capacity?
A) amps
B) kilovolt-amps
C) volts
D) watts
kilovolt-amps
Live parts to which an employee might be exposed must be deenergized before the employee works on or near them, unless ___ determines that deenergization introduces additional or increased hazards or is infeasible due to equipment design or operational limitations
A) employee
B) employer
C) foreman
D) job steward
employer
A circuit supplied with a 277-volt, 60-hertz source is connected to a circuit with a capacitive reactance of 23.35 ohms. What is the current?
A) 5.42 mA
B) 11.86 mA
C) 8.48 A
D) 11.86 A
11.86 A
nonmetallic sheathed cable shall be secured in place at intervals not exceeding ___ and within 12” from every box and cable termination.
A) 2’
B) 4.5’
C) 6’
D) 8’
4.5’
If the frequency of a capacitive circuit is decreased, the current will ___
A) decrease
B) first decrease then increase
C) increase
D) stay the same
increase
(parellel circuit with R=10 ohms, Xc=8 ohms, and Ir=8A.)
Determine the source voltage.
A) 64 V
B) 80 V
C) 120 V
D) 160 V
80 V
Three-way and four-way switches shall be so wired that all switching is done only in the ___ circuit conductors.
A) grounded
B) grounding
C) neutral
D) ungrounded
ungrounded
Overhead spans of outdoor open conductors, rated at not over 1000 volts, shall have a minimum clearance from grade of ___ over streets and roads.
A) 12’
B) 18’
C) 20’
D) 24’
18’
A motor consumes 248.67 watts of power. What is the horsepower rating of the motor? (neglect heat losses)
A) 1/8 hp
B) 1/4 hp
C) 1/3 hp
D) 1/2 hp
1/3 hp
(1 hp = 746 W)
Match the term “henry” with the choice that closest describes its use.
A) Unit of capacitive reactance
B) Unit of frequency
C) Unit of inductance
D) Unit of inductive reactance
Unit of inductance
In a series LC circuit, when Xc equals Xl, the total impedance Z ___.
A) approaches maximum
B) approaches minimum
C) cannot be determined
D) is not affected
approaches minimum
(Symbol with a circle sitting on top of a square with two lines coming out of the bottom of the square)
Identify the item.
A) Bell
B) Buzzer
C) Horn
D) Relay
Bell
Which type of view gives a pictoral representation of an object on a drawing?
A) auxilliary view
B) holographic
C) isometric
D) orthographic
isometric
A circuit has a coil with inductance of 3 henries and is connected to a 60 hz 120 volt source. What is the current?
A) 98 mA
B) 106 mA
C) 114 mA
D) 122 mA
106 mA
How many degrees separate the phases of a 3 phase transformer system?
A) 30
B) 60
C) 90
D) 120
120
The two standards applicable to the majority of the work performed by electrical workers are found in part 1926 and … 1910 applies to ___.
A) Construction / General Industry
B) General Industry / Construction
C) Health / Safety
D) Safety / Health
General Industry / Construction
A single winding transformer is mroe commonly known as a(n) ___.
A) autotransformer
B) corner grounded delta transformer
C) delta-wye transformer
D) neutral grounded wye transformer
autotransformer
How much power in kilovolt amps is delivered to a 3 phase transformer when the line voltae applied is 240 volts and the …
A) 12.47 kVA
B) 14.47 kVA
C) 14.53 kVA
D) 22.37 kVA
14.47 kVA
In a pure inductive circuit, the voltage and the current are ___ with each other.
A) in-phase
B) 90 degrees out of phase
C) 120 degrees out of phase
D) 180 degrees out of phase
90 degrees out of phase
Which of the following is not identified as a method of ensuring an electrically safe work condition.
A) barricaded to prevent access by unauthorized persons
B) disconnected form energized parts
C) locked/tagged in accordance with established standards
D) tested to ensure the absence of voltage
barricaded to prevent access by unauthorized persons
A ___ is an electromagnetic device that changes voltage form one level to another.
A) generator
B) motor
C) panelboard
D) transformer
transformer
To find information about light fixtures on the job including fixture types, manufacturers, lamp numbers, and mounting instructions, look in the ___.
A) equipment schedule
B) lighting fixture schedule
C) lightning panel schedule
D) room schedule
lightning fixture schedule
(Symbol that is a big “S” with a subscript “P”)
Identify this item.
A) Keyed switch
B) Pull switch
C) Surface mounted switch
D) Switch with pilot light
Switch with pilot light
What type of plan shows the location of the structure in relation to the lot, road, or other nearby structures.
A) Elevation
B) Floor
C) Plot
D) View
Plot
(TRANSFORMER DIAGRAM | Primary - A-B B-C C-A with a jumper between coils. Secondary - A-N B-N C-N with a jumper between coils)
Identify the connection types on the transformer.
A) Primary delta high - secondary delta high
B) Primary delta high - secondary wye high
C) Primary delta low - secondary delta low
D) Primary delta low - secondary wye low
Primary delta high - secondary wye high
In guest rooms in hotels, motels, and similar occupancies, receptacle outlets shall be permitted to be located … least ___ receptacle outlets shall be readily accessible.
A) 1
B) 2
C) 4
D) 6
2
(Picture of a sine wave)
the figure shown is a(n) ___.
A) complete DC cycle sine wave
B) output wave for a pulsating DC generator
C) 3-phase motor output wave
D) wave shape of an AC voltage sine wave.
wave shape of an AC voltage sine wave.
Outlet boxes that do not enclose devices or utilization equipment shall have a minimum internal depth of ___.
A) 1/2”
B) 3/4”
C) 1”
D) 1 1/2”
1/2”
Arc rated suits and clothing are designed to protect electrical workers from ___.
A) arc-blast
B) arc-flash
C) electrical hazards
D) electrocution
arc-flash
Each multiwire branch circuit shall be provided with a means that will simultaneously disconnect all ___ conductors.
A) equipment grounding
B) grounded
C) grounding electrode
D) ungrounded
ungrounded
(Circuit diagram with R=10 ohms, Xl=12 ohms, and Xc=8 ohms)
Determine the total impedance Z in the figure.
A)10.8 ohms
B) 14 ohms
C) 15.6 ohms
D) 30 ohms
10.8 ohms
It takes ___ time constants to fully charge a capacitor.
A) 3
B) 4
C) 5
D) 6
5
(Circuit diagram of a parallel circuit. Source is 120 V 60 Hz. It=4 A. I2=1 A)
The current through branch I1 is ___.
A) 1 A
B) 2 A
C) 3 A
D) 4 A
3 A
Two capacitors of 3 and 6 microfarads are connected in parallel to a 120 volt 60 hertz source. What is the max …
A) 0.407 mA
B) 9.04 mA
C) 0.407 A
D) 9.04 A
unknown
In every kitchen, family room, dining room, living rom, parlor, library, den, sunroom, bedroom, recreation room .. outlets shall be installed so that no point along the floor line in any wall space is more than ___, measured horizontally.
A) 3’
B) 5’
C) 6’
D) 12’
6’
(Transformer diagram showing a delta-wye low-low configuration)
If each secondary winding is rated at 120 volts AC (VAC), what would the voltage be between …
A) 120 VAC
B) 208 VAC
C) 240 VAC
D) 277 VAC
208 VAC
A 380 millihenry coil has 12 volts at 60 hz dropped across it. What will the current be flowing through this coil?
A) 31.6 mA
B) 83.8 mA
C) 157.9 mA
D) 187.6 mA
83.8 mH
The schedule that lists details realting to circuits, breakers, and the main disconnect is the ___ schedule.
A) electrical
B) equipment
C) panel
D) room
panel
(Single phase transformer with a neutral reference tap between secondary coils)
In the secondary winding of the single phase transformer, if the current in phase A is 25 amps and the current in phase B is 25 amps, what is the current on the neutral?
A) 0 A
B) 12.5 A
C) 25 A
D) 50 A
0 A
When the frequency of a purely inductive circuit is decreased, the current in the circuit ___.
A) decrease
B) increase
C) increase proportionally to the resistance
D) remain the same
Key says increase but I think decrease
Which transformer connection shows a transformer that is connected in a primary delta low, secondary wye low connection
Primary will be A-B B-C C-A with cross jumpers. Secondary will be A-N B-N C-N with cross jumpers.
In general, all service entrance conductors entering or on the exterior of buildings or other structures shall be ___.
A) covered
B) grounded
C) guarded
D) insulated
grounded
The primary leads of a transformer are identified with the letter ___.
A) H
B) P
C) S
D) X
H
The skin’s ___ can change as a function of the moisture present in its external and internal layers.
A) resistance
B) roughness
C) softness
D) thickness
resistance
(Symbol of a Square with a slight rising diagonally from its bottom left side, and a circle with a dot in the middle touching its right side)
Identify the item
A) Bell
B) Ceiling fixture with internal switch
C) Combination bell/buzzer
D) Low-voltage light fixture
Combination bell/buzzer
Connecting additional inductors in a series circuit will cause the circuit current to ___.
A) decrease
B) increase
C) increase proportionally to the resistance
D) stay the same
stay the same
(TRANSFORMER DIAGRAM | Primary - A-B B-C C-A with jumper between coils. Secondary - A-B B-C C-A with jumper between coils.)
Identify the connection types of the transformer
A) Primary delta high - secondary delta high
B) Primary delta low - secondary delta low
C) Primary delta low - secondary wye high
D) Primary delta high - secondary wye low
Primary delta high - secondary delta high
A 480-ohm inductor has a voltage drop of 40 volts across it. How much current is flowing through the coil?
A) 0 mA
B) 0.41666666 mA
C) 83 mA
D) 120 mA
83 mA
For a wye-connected transformer, the current carried by the windings is ___ the line current of the phase …
A) equal to
B) one half
C) 0.58 times
D) 1.73 times
equal to
A 750 microfarad capacitor is connected to a 277 volt 60 hz source circuit. How much current …
A) 980 mA
B) 78.28 A
C) 282.5 A
D) 980.18 A
78.28 A
(Circuit diagram with a 120v 60hz source. It=8 A. I1=6A, R1=20 ohms. I2 and R2 and unknown)
The value of R2 is ___.
A) 2 ohms
B) 3 ohms
C) 20 ohms
D) 60 ohms
60 ohms
There are three capacitors in parallel. Their values are C1 = 0.25 uF, C2 = 0.3 uF, and C3 = 0.35 uF. What is the total capacitance?
A) 0.009 uF
B) 0.090 uF
C) 0.900 uF
D) 9.000 uF
0.900 uF
