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