Electrical Theory
a 100 watt lamp is on a 120 volt circuit measured at 144 ohms. a dimmer is to be connected to reduce the voltage to 60 volts. what resistance is needed?
144 ohms
Given: A low voltage remote control lighting system is supplied by a low voltage transformer with an output rating of 72 VA at 24 volts, each switching relay draws 0.2 amps. Disregarding inrush current, what is the maximum number of relays that may be switched at the same time?
15
if an electrical service line drops the voltage from 255 to 240 volts. What is the line efficiency?
94%
Refer to the drawing ; The contacts labeled 'M1 are referred to as:
Holding or maintaining contacts
A 240 volt single phase circuit has a non-continuous resistance load of 8400 watts. What is the current drawn by this load?
35 amps
A motor is drawing 1000 watts in a 120 volt circuit with 9 amps going through it. What is the power factor of the motor?
92.5
Refer to the illustration. With a 9 amp current in the circuit what is the power factor?
93%
Refer to the illustration, where should the lead marked. '?' be connected to allow this motor to run correctly on 115 volts?
A
Refer to the illustration; What resistors are in series?
R1+R2, R3+R4, R5+R6, R7+R8
Refer to the illustration: What resistors are in parallel?
R1+R5+R7+R3, R2+R8+R6+R4
In order to determine amperage in a circuit, the amp meter should be hooked up in __________.
Series
When measuring current the meter would be connected in _______.
Series
Which type of circuit has it's components connected end to end?
Series
Which of the following makes a high voltage Delta connection
T2-2, T3-3, T1-1, 8-5, 4-7, 9-6
Which of the following makes a low voltage delta connection
T2-2-8-4, t3-3-5-9, t1-1-7-6
Which of the following makes a low voltage Wye connection?
T3 3-9, T2 2-8, T1 1-7, 6-5-4
How much will it end up costing to run a 208 volt heater, rated at 2.4 Kw, if it runs for 8 hrs a day for 24 days at a cost of 12 cents per Kwh?
$55.30
A non inductive heating coil in a 12 volt circuit uses 6 watts, how much power would be used in a 24 volt circuit?
24 watts
a 24 volt, 6 watt heating coil, if the coil is connected to 48 volts, how much power will it use?
24 watts
What makes current flow?
Electromotive Force
What are the two principle effects of electrical current in a circuit?
Heating and Magnetic
What causes variance in sine wave lighting loads in a 4 wire, 3 phase wye circuit?
harmonics
What would happen to amperage if you double the voltage and halve the resistance in a circuit?
it quadruples
The resistance of a 2/0 uncoated copper conductor is .0967 Ohms per 1000 feet. What would be the total resistance for 3-2/0 copper conductors installed in parallel if the total length of each conductor is 243 feet?
0.0078 Ohms
Two inductors rated at 45 mH and 55mH are connected in parallel, what is the total inductance?
0.0247 H
The source voltage to a load is 120-V. An electrician measures a voltage drop of 3.33% at the load. The load carries 25 amperes. What is the resistance of the wire to the load?
0.16Ω
an inductor with an inductance of 3.6H is connected toa 480 volt, 60 Hz line. How much current will flow in the circuit?
0.354 Amps
A circuit with 3.6 Henry and 480 volts, 60 Hz. How much current will flow in the circuit?
0.354 amps
Given: A series circuit consisting of a battery and a resistor has the following values: Battery voltage = 1.5 volt Total Current = 2 amps What is the resistance of this circuit?
0.75 ohm
Refer to the illustration. Where is the coil starter located?
1
Refer to the illustration. What is the current in the 2 ohm resistor?
1 amp
Given: An electric heater is rated 1500 watts at 230 volts. How much wattage will actually be dissipated when connected to 208 volts?
1,227 watts
A range draws 50 amperes when used on a circuit. a bad splice is discovered on the line at the range on one of the phase conductors. The splice has a measured resistance of 0.4Ω How much power is lost at the splice?
1.00 KW
What is the voltage in a circuit with 23 Ohms resistance and 45 milliamps?
1.035
A step up transformer has a 120 volt primary at 5 amps. What is the current in the secondary at 480 volts?
1.25 A
What would the minimum size wire need to be for a 120 volt, single phase, electric sign drawing 16 amps that is 900 feet from the source. The maximum voltage drop allowed is 3%. K=12.9
1/0 awg
A florescent lighting bank in a commercial location operates for 8-hours per day. Each fixture has two ballasts rated at 0.8 amps each. How many lights can be wired to a 20-amp circuit breaker?
10
if a solar panel system is being installed and the system has a maximum capacity of 800 watts and 48 volts, how many panels can be used if each panel is 75 watts and 12 volts?
10
How many amps are drawn by a 1.02 kilowatt load that operates at 85% power factor on a 120 volt single phase circuit?
10 amps
A company has an electrical contractors license. The master Electrician decides to leave the company. How many days does the company (Licensee) have to notify the division?
10 days
Refer to the illustration. A 50 volt generator is connected to 4 resistive loads. What is the voltage drop across the 10 ohm load?
10 volts
Given: A 2 kW load is supplied by a 240 volt single phase circuit with a 80% power factor. What is the measured current carried on each conductor?
10.4 amps
The primary side of a transformer is 240 volts and the secondary side is 24 volts. What is the ratio of the transformer?
10:1
An old 120 volt 0.5 horsepower, 80 % efficient ventilation fan is replaced by a new 120 volt 0.5 horsepower fan that is 90 % efficient. When running, the new fan will draw what percent less current than the old fan?
11%
An old ceiling fan is to be replaced with a new ceiling fan. The old ceiling fan is rated at 120 Volts, 80% efficiency, with a 1/2 hp motor. The new fan is rated at 120 volts, 90% efficiency, with a 1/2 hp motor. What is the power savings of the new motor?
11%
A single phase electric kiln operates at 208 volts on a 240 volt system and draws 53 amps. how much power does it consume?
11,024 watts
an 11 ohm resistance is the only load connected to an 11 volt source. What is the power used?
11.0 watt
15 horsepower is equivalent to which of the following?
11.19 kw
What will the voltage drop be on 540 feet of 4/0 copper on a 200 amp, 480 volt 3 phase circuit? K=12.9
11.39 volts or 2%
What is the voltage drop in a 3 phase circuit using 4/0 copper wire 540 feet long at 480 volts and drawing 200 amps?
11.4
Refer to the illustration. The current through R1 and the lamp (L1) is equal to 0.267 amps. What value of resistance could be installed at R2, in series with the lamp and R1, to reduce the total current by half?
119.8 Ohms
Refer to the illustration, assume 100 percent efficiency. What is the maximum possible value of current lx?
12 amps
a 120v, single phase , 1.5 HP motor is 90 percent efficient and has an 85 percent power factor. How much current will this motor draw?
12.19 amps
At 240 volts a resistant heater would consume 1500 watts. Two of these heaters are connected in series; Then the combination is connected to 240 volts. What is the current in this series circuit?
12.5 amps
Four 50 ohm resistors are connected in parallel across a 100 volt source. What is the total circuit resistance?
12.5 ohms
What is the total impedance of a circuit that has a resistance of 8 ohms, and inductive reactance of 22 ohms and a capitative reactance of 32 ohms?
12.8 ohms
Three phase power is how many degrees out of phase with each other?
120
What is the line to ground/neutral voltage ona 120/240 volt, 3 phase, 4 wire Delta transformer?
120 volts
Which voltage is not a wye configuration?
120/240
Refer to the illustraion: On the following 120 volt circuit, and given that R1 is 20 ohms, R2 is 30 ohms, and R3 is 40 ohms, what is the total amperage?
13 amps
Electricity costs $0.085 per kilowatt hour. How long can a 4.5 kilowatt oven be continuously operated for total electrical cost of $5.00?
13 hours
According to ohms law, how many amps does a 5 hp, 200 volt, 3 phase motor draw? the motor has 92% efficiency and 90% power factor.
13.02
Refer to the illustration. What is the voltage across the two parallel 28.8 ohm resistors in this circuit?
13.68 volts
a 480 volt, 3 phase, at 168.4 amps is how many KVA?
139.8
A 1000 watt, 120 volt lamp uses electrical energy at the same rate as a _____ ohm resistor.
14.4
What is the maximum load allowed in a single phase aluminum wire with 120 volts, 4 awg wire, 240 feet long and a 3% voltage drop?
14.7 amps
What is the KVA of a 3 phase load operating at 480 volts and 168.4 amps?
140
if you upgrade five(5) 75 w lamps to 11w LED lamps, how many hours will it take to make your money back if the LED's are $19.00 each and you are charged 9.7 cents per Kwh?
15,300 hours
Refer to the illustraion: On the following 120 volt circuit, and given that R1 is 20 ohms, R2 is 30 ohms, and R3 is 40 ohms, what is the total wattage?
1560 watts
What is the total capacitive reactance of a 95 microfarad and a 71 microfarad capacitors in parallel?
16
Given: An electric range supplied by spliced conductors draws a measured 40 amps, one bad splice is found to have a measured resistance of .01 ohms. How much power is lost at the splice?
16 watts
Given: The load on a 240 volt single phase circuit is a resistance heater rated at 4000 watts. How much current does the heater draw?
16.7 amps
Given: An electric range supplied by spliced conductors draws a measured 40 amps, one bad splice is found to have a measured resistance of 0.1 ohms. How much power is lost at the splice?
160.0 watts
Given: An electric range supplied by spliced conductors draws a measured 40 amps. One bad splice is found to have measured resistance of 0.1 ohms. How much power is lost at this splice?
160.0 watts
Refer to the illustration: if a resistor is installed in series with the lamp, what size would be needed to cut the amps in half?
165.5 Ohms
2 capacitors are connected in parallel, one is 95 uf and the other is 71 uf. what is the capacitance?
166
Refer to the illustration, What is the total resistance if R1 =100, R2=100, R3=100, and R4=100?
166.66 ohms
62.6 degrees Fahrenheit is what degree in Celsius?
17
Given: The secondary of a transformer supplies 120/240 volt, 60 hertz, single phase power. All loads are 120 volts. The line 1 to neutral load is 5760 VA. The line 2 to neutral is 3,720 VA. What is the current in the neutral conductor?
17 amps
What is the peak voltage of a 120 volt RMS circuit?
170
A building has a 120/208 volt three phase service with a balanced net computed load of 63 KVA. At full load each ungrounded wire in this service is carrying. current of:
175 amps
A 120 volt branch circuit has a load of 10 amps. The conductor length is 500 feet, and the wire has a resistance of 1.75 ohms per 1,000 feet. What is the voltage drop?
18
Given: A 240/480 volt 3 phase power panel board supplies only the following load: 1 - 15,000 VA, 480 volt, 3 phase balanced resistive load. Each ungrounded conductor in the sub-feeder to this power panel has a total net computed load of how many amps?.
18 amps
A fire alarm indicating appliance is installed as follows: Source voltage: 24 volts, AC distance between alarm panel and the indicating appliance: 1,500 feet (3,000 feet of conductor). Conductor: Size 12 AWG uncoated copper. Current drawn by the indicating appliance: 1 amp Power factor: Consider power factor as 1 (unity) What is the voltage at the appliance terminals for the installation described above?
18 volts
A current of 0.19 amps equals how many millamps?
19
What degrees F is 90 degrees C?
194
According to Utah state law, what is the ratio of apprentices to journeyman or master electricians on a commercial, institutional, or industrial jobsite?
2
Refer to the illustration, how many volts between points A and point B?
2
Refer to the illustration. This 3 point saddle has 2 - 45 degree bends and 1 90 degree bend. if the height ' H' of the bend is to be 2 inches, what is the approximate length 'L'?
2 13/16 inches or 2.8 inches
Given: An electrical installation requires a total of 200 feet of conductor (100 feet out and 100 feet back). The line can have a maximum resistance of 0.5 ohms. What is the maximum resistance allowed per 1000 feet for this conductor?
2.5 ohms
A lighting and electric space heating panel board has the following loads: 150 amps at 120 volts connected from each phase to the neutral; 1,50 amp 3 phase load connected phase to phase. What is the total current in each busbar?
200 amps
What is the power consumed by a 5 ohm resistor if it is connected across 10 volt source?
20 watts
Given: The largest available conductor for an electrical installation has resitance of 1.5 ohms per 1000 feet. To meet the voltage drop specification, the maximum resitance the circuit is 0.3 ohms. What is the maximum combined conductor length for this circuit?
200 feet
What is the resistance in ohms of 1 circular mil foot of aluminum at 75 degress C?
21.2
Given: Two wires provide power to a remote load. The wire resistance is 0.2 ohms (0.1 ohm per wire), the source voltage in to these wires is 25 volts and the measured circuit current is 10 amps. What is the voltage across the remote load?
23 volts
Given: a 240 volt branch circuit is allowed a maximum voltage drop of 4 percent. The minimum voltage at the branch circuit load is _______ volts?
230.4 Volts
What is the secondary current of a 240/480, 112.5 kva step-up transformer?
234 amps
You have a 10 Gauge wire with 440 volts 3 phase and 250 amps, there are 1.75 ohms per 1000 feet. What is the maximum length of the wire allowed without exceeding the 3% voltage drop?
24.5 feet
What is the minimum voltage of a 15 hp motor?
240
if a transducer puts out 4-20 mA, what size resistor would be needed in order for a signal recorder to read 1-5 volts?
250 ohms
on a 3 phase load, what is the amperage on the neutral conductor if A is 70 Amps, B is 83 amps, and C is 100 Amps?
26 amps
What is the total resistance of a 45 ohm and a 75 ohm connected in parallel?
28.12
In the state of Utah what is the maximum number of stories on a commercial building allowed With a Residential/ Small Commercial License?
3
A 36 KVA, 208 volt, three phase load is loacated 80 feet from the panelboard and is wired with 1 awg THHN aluminum. What is the approximate voltage drop of the circuit conductors?
3.5
What is the voltage drop on a 350 kcmil THHN copper wire 160 feet long supplying a 300 amp single phase load? K=12.9
3.54 volts
One thirtieth (1/30) of a second is equal to how many hertz?
30
After doing a job that has material costs, labor costs and travel expenses. What is considered a timely manner in which to be paid?
30 days
Given a 10,860 watt load on a 3 phase, 208 volt circuit, Assuming a balanced load, what is the current on each phase?
30.18 amps
What is the total impedance of a circuit that has a resistance of 20 ohms, and inductive reactance of 30 ohms and a capacitive reactance of 5 ohms?
32 Ohms
A 440 V, 3-phase branch circuit is to be installed with three, 4/0 awg, THW , copper conductors serving a load of 250 amperes. Determine the maximum length of the conductors with the voltage drop not exceeding 2 percent.
334 feet
Refer to the illustration; Calculate the voltage between points "A" and "B".
339 volts
What is the power loss in a single phase, 120 volt circuit using #6 THW copper wire, 100 feet long and drawing 60 amps
354 watts
Given: A 100-watt lamp is rated at 144 ohms. A dimmer switch reduces the voltage across the lamp by inserting resistance in series with the lamp. Th e voltage across the lamp is to be reduced from 120 volts to 90 volts. What Resistance will be required?
36.014 ohms
A single family residence has a lighting load of 6000 va, the minimum number of 15 amp branch circuits is?
4
Six (6) equal resistors are connected in series to a 24 volt source. What is the voltage drop across each resistor?
4 volts
What is the voltage drop in a single phase 240 volt circuit using #8 copper wire 175 feet long and drawing 35 amps?
4%
What is the voltage of a set of speakers that are at total fo 200 watts with 8 ohms of resistance?
40
A 3 Phase, 208 volt motor draws 26 amps. It is a 200 feet from the distribution panel using #6 THWN copper conductors. What is the Voltage drop on this line? K=12.9
4.4
A 3 phase,208 volt motor draws 26 amps . it is 200 feet from the distribution panel using #6 thwn copper conductors. what is the voltage drop on this line? K=12.9
4.4
An emergency light has two 6 volt, 7.5 watt lmaps wired in series to a 12 volt battery. One of the lamps is burned out. What size resistor must be used to replace the lamp to make the one good lamp operational?
4.8 Ohm
A coil of 10,380 circular mill copper wire has a resistance of 0.5 ohms. What is the length of the wire?
400 feet
Refer to the illustration, if R1=300, R2=100, R3=100, R4=100 and R5 = 100, what is the total resistance of the circuit?
400 ohms
a 30 uf capacitor is connected to a 240 volt, 1,000 hz circuit. what is the current?
45.28 amps
Refer to the illustration, what is the total resistance in the circuit?
466.67
Refer to the illustration. How much power is consumed by the resistors in this circuit?
47 watts
Which of the following represents the resistor color code: yellow, violet, red?
4700.0
Given: A 20 kilowatt, 240 volt, 3 phase resistance heater is supplied by a 120/240 volt 3 phase panel. What is the current in each of the ungrounded branch circuit conductors?
48.1 amps
Refer to the illustration: On the following 120 volt circuit, and given that R1 is 10 ohms, R2 is 20 ohms, and R3 is 30 ohms, what is the wattage at R3?
480
Given: A 3 phase, 480 volt transformer rated at 75 KVA and a. impedance of 18 percent. What is the maximum short circuit current of this transformer
496.177 amps
A large room requires the installation of 30 luminaires, each with a nameplate rating of 300 watts. The maximum wattage on any circuit is 1800 watts. How many circuits are needed to power the luminaires?
5
What is the horsepower of a 240 volt single phase motor that draws 15.75 amps?
5
a 120 volt circuit has 3 heaters with resistances of 4 ohms, 5 ohms and 15 ohms. if these resistances are connected in series what is the current?
5 amps
A 240 volt, single phase motor draws 15.54 amps, What is the horsepower of this motor?
5 hp
A water heater with a nameplate rating of 5,000 watts at 230 volts is connected 240 volts. What is the heater output in watts?
5,444.24 watts
A 1.5 HP single phase motor has an electrical efficiency of 85% and operates at 230 volts. For the purposes of this question, 1 hp = 746 watts. What is the input current of this motor?
5.7 amps
Calculate the voltage drop on a 3 phase, 480 volt branch circuit of 1 awg, THW, Aluminum, carrying 90 amps a distance of 150 feet
5.91
How many milli-seconds is point A?
50
if you have 700KW at a 60% power factor, how many KVA would you have at a 90%. power factor?
594 KVA
A hair dryer is plugged into the furtherest outlet, the voltage at the load center is 120 volts, if the voltage drops to 112 volts, what percent is the voltage drop?
6.6%
Refer to the illustration. This 3 point saddle has 2-30 degree bends and 1-120 degree bend. if the height 'H' of the bend is to be 3 inches, what is the appropriate length ' L'?
6 inches
A battery with 12 volts on its terminals is charged with a 16 volt charger. In order to dorp the charging voltage from 16 to 12 volts with a current of 2 amps. What should the total resistance in the circuit be?
6 ohms
Refer to the illustration. Assume 100% efficiency. What is the AC voltage between terminals x1 and x2
6 volts
A 208 volt, 3 phase 750 kcmil AL feeder is 300 feet long with a 400 amp load. branch lines are 3 phase, 1/0 THW AL to a 3 phase machine drawing 120 amps that is 157 feet from the source. What is the voltage drop percentage for the feeder and the branch? K= 21.2
6%
Refer to the illustration. if height 'H' of the offset in 1/2 inch emt (electrical metallic tubing) is 3 inches. What is the length of 'L'?
6.0 inches
What is the impedance in a 240 volt, 35 amp circuit?
6.86 ohms
What is the impedance of a 240 volt circuit that draws 35 amps?
6.86 ohms
A circuit has one 10 ohm, one 20 ohm and one 30 ohm resistors connected in series on a 120 volt line, what is the total resistance?
60
Refer to the illustration, R1= 10 watts, R2 = 20 watts, and R3 = 30 watts, how much power is used in this circuit?
60 watts
What is the calculated current through a 15 KW heater operating at 240 volts?
62.5 amps
A 120 volt, single phase motor draws 14 amps. Using #12 THHN copper conductor there is a 3% voltage drop on the line. How far from the panel is the motor? K=12.9
65 feet
How much power is consumed in a circuit which operates at 115 volts, draws 8 amps, and has a power factor of 80%?
736 watts
a 240 volt single phase circuit has an 11 KW load and 62 amps of current. What is the power factor?
74%
Due to the length of conductor wire to a 480/277 volts parking lot lighting system, the installer must increase the size of the ungrounded conductors from 6 awg to 4 awg to compensate for voltage drop. The circuit breakers to the lighting system is sized at 60 amps. What size equipment grounding conductor must be installed to the light poles?
8 awg
Refer to the illustration: What is the voltage through R1?
80 volts
Refer to the. illustration: On the following 120 volt circuit, and given that R1 is 20 ohms, R2 is 30 ohms, and R3 is 40 ohms, what is the total resistance?
9.23 ohms
What is the power factor of a motor drawing 100 watts in a 120 volt circuit with 9 amps going through it?
9.25%
Ampere meters measure which of the following values?
Amperes
KVA is defined as?
Apparent Power
Refer to the illustration, if each resistor is 10 ohms, which group of resistors has the most resistance?
B
Instant start fluorescent lamps will not operate without a __________.
Ballast
Given: 3 resistance heaters are connected in parallel. Their resistance's are as follows: heater 1 48 ohms; heater 2, 24 ohms; heater 3, unknown; heater total+ 15 ohms. What is the resistance of heater 3?
Between 231 and 260 ohms
Resistance can be measured with which of the following types of instruments?
Both Ohmmeter and Megohmmeter
An electrical component made up of two conducting materials that are separated by insulation and allows electricity to be stored is called?
Capacitor
The ability of a material to PERMIT the flow of electrons through it is called?
Conductance
Transformer windings are wound around a :
Core
The rate of current flow is equal to electromotive force divided by resistance, which represents a value of ________.
Coulombs
Refer to the illustration which figure is a kick in a conduit?
D
Refer to the illustration, Which diagram shows a 4 way switch properly connected
D
Refer to the illustration, if each resistor is 50 ohms and rated at 0.5 watt, which group of resistors will give you 50 ohms total with at least 2 watts?
D
What defines electrocution
Death
Refer to the illustration, what type of switch is this?
Double pole, double throw
A glass bulb with a filament under vacuum is what type of light?
Incandescent
As a conductive metal becomes hot, the resistance ______.
Increases
Who is responsible for Electrical work on the job site according to utah state law?
Journeyman and Master Electricians
A circuit connected in parallel will carry ______ amps than one connected series. ( This question assumes equal voltage and resistance)
More
Refer to the illustration, the contacts preceding coils F and R are called?
Normally closed
Electrical apprentices, journeyman, and master must renew their licenses when?
November 30 of even numbered years
The relationship between current,resistance and voltage is known as?
Ohms Law
Possible phrasing... When the free ends for testing are touched to a closed circuit of not too high resistance, the bell rings, if the circuit is ______ , the bell will not ring.OR two #18 conductors, one is connected toa bell and one is connected to ground in conduit. when the two wire are connected together the bell rings, when not connected together the circuit is:
Open
A circuit contains only resistors R1 and R2 . The current through R1 is 15 amps and the current through R2 is 15 amps. if the common circuit feeding both resistors is a current of 30 amps, R1 and R2 are connected in:
Parallel
Refer to the illustration, what type of circuit is this?
Parallel
Refer to the illustration, which type of circuit is indicated?
Parallel
When circuit components that are connected across the source they are called?
Parallel
When measuring voltage the meter should be connected in?
Parallel
Which type of circuit has components that look like a ladder?
Parallel
Watt hour is a measurement of the consumption of?
Power
The term kilowatt, indicates:
Real power
What should be done if the motor is running in the wrong direction?
Reverse the field connection
Refer to the illustration, What type of chart is this?
Sine Wave
The input to a transformer is 240 volts and the output is 24 volts. This is known as a _________ transformer.
Step Down
if W=VA, then which of the following statement is true?
True power equals apparent power
Which of the following is used to correctly test busways (bus duct)?
Volt/Ohm meter
In a DC power formula, amperage is multiplied by
Voltage
The total__________ in a series circuit is equal to the sum of the voltages across all parts of the circuit.
Voltage
When measuring potential difference of a circuit, the unit of measurement is?
Voltage
The current which a conductor can carry continuously under the condition of use without exceeding its temperature rating is defined as a :
ampacity
Refer to the illustration, which represents a back to back raceway installation and the emt bender. Do not not consider the horizontal stub. Which arrow should be aligned with which mark on the raceway when placing this emt bender to make the bend at the lef end of this figure
arrow Z to mark A
The total opposition to AC in a circuit which includes resistance, inductance and capacitance is called:
impedance
When metals become hot, the resistance?
increases
The rate of flow of the current is equal to electromotive forces divided by resistance, what does I equal?
intensity of current
The flow of electromotive force divided by the opposition to flow of current is known as what?
ohms law theory
An incomplete circuit path is called a (an) _______ circuit.
open
What color identifies the "B" phase of a 240 volt, delta, three phase, 4 wire with a high leg?
orange
Which of the following converts AC to DC with no moving parts?
rectifier
Which of the follwoing makes a high voltage wye connection?
t3-3, t2-2,t1-1,6-9,4-7,5-8
Consider the following information; One 100 watt lamp runs 8 hours per day for 30 days at 8.5 cents per kilowatt hour. Another 14 watt lamp runs 8 hours per day for 30 days at 8.5 cents per kilowatt hour. What is the cost comparison between these two lamps over the course of a year?
the 14 watt lamp will cost 86 percent less than the 100 watt lamp per year
A 240 volt electric heater is rated at 1000 watts. what would happen if it was accidentally hooked up to 120 volts?
the heater will only heat 1/4 as good?
Refer to the illustration of the circuit tracing identification problem. Given: An electrician arrives to hook up a 3- way switch. the conductors have been installed by another crew. In order to determine how these conductors are hooked up to a switch certain continuity tests are made, power is not connected to the circuit nor is there a load connected. All connectors are the same color. With conductors 1,2 and 3 all connected together, the following continuity is observed. A to B open, A to C shorted, B to C open. Which of the following pairs are the travelers?
AC
Ten (10) amperes of current through which of the following will produce the most heat?
a resistor with 10 ohms impedance
Refer to the illustration. if the balanced load draws 20 amps through each ungrounded conductor, what will be the reading on this clamp on amp meter
0 amps
if a strand on a wire has a cross-sectional area of 10,000 circular mils, the diameter of the strand is
0.1 inches
Given: A 240 volt branch circuit is allowed a maximum of 4.8 volts. The load on the circuit draws a maximum current of 30 amps. What is the maximum resitance allowable for the conductors of this circuit?
0.16 ohms
Refer to the illustration. What is the current which is drawn by resistor R2?
1 amp
A conservative formula for determining the maximum available short circuit current ( ISCC) available at the secondary of a transformer, when the primary source is assumed to be of unlimited capacity is: ISCC = 100% x Is /Zt% Where (Is) is the full load current rating and (Zt) the rated impedance voltage percentage of a given transformer. A 75 KVA transformer has only one 240 volt untapped secondary winding. The transformer impedance ( Zt) equals 2 percent. What is the short circuit current(ISCC) available at the transformer secondary?
15,625 amps
A 240 volt AC single phase motor draws a line current of 10 amps and has a power factor of 90%. The input power consumption of the motor is?
2160 watts
Given: A 3 phase transformer secondary is delta connected to a balanced non inductive load. The line to line voltage is 480 volts and the total load on the secondary is 18 KVA. What is the current in each ungrounded conductor?
22 amps
Refer to the illustration, if the neutral at poin 'x' is open, what is the voltage across the motor 'M2'?
240 volt
A single phase 480 to 240 volt stepdown transformer is rated at 12KVA. The transformer may be loaded to a maximum current in each secondary line conductor of?
25 amps
What is the maximum number of apprentice electricians that a journeyman or master electrician may supervise on a residential job?
3
A 240 votl source has a 20 amp load. What is the kVA of this circuit?
4.80 kva
a 120v branch circuit has only 6, 100 watt 120 volt incandescent light fixtures connected to it. What will be the total measured current in the home run supplying this load?
5 amps
Given: Four electric heaters are installed and the resistance rating of heaters are as follows: heater no. 1 is 20 ohms, heater no. 2 is 30 ohms, heater no. 3 is 60 ohms, heater no. 4 is 10 ohms. if the heaters are wired in parallel what is the total resistance on a 240 V circuit? Select the closest answer.
5.0 ohms
Given: A pair of conductors supply a 12 amp, 120 volt load that is located 150 feet from the source. Each of the conductors has cross sectional area of 6,530 circular mills and a resistivity constant of 10.4 ohms per circular mill. What is the total voltage drop in the supply conductors?
5.73 volts
Given: Three heaters(R1, R2, R3) are installed in a series circuit. The power used by R1 is 100 watts and the power of R2 is 75 watts. The power used by the entire circuit is 225 watts. How much power is used by heater R3?
50 watts
The switches on the multi meter are set to AC and 10 volts. This meter indicates a reading of:
6.4 volts
A pair of conductors supply a 12 amp, 120 volt load that is located a distance of 150' from the source. The two size 12 awg conductors that feed the load have a resistance of 1.93 ohms per 1000 feet. What is the voltage drop across the supply conductors?
6.950 volts
What is the maximum rated current that a 240 volt single phase, 15 KVA generator will provide?
62.5 amps
Given: A generator receives 10 HP and delivers 20 amps at 240 volts. One HP is equal to 746 watts. What is the efficiency of this generator?
64.3%
A 2 Hp single phase motor which has a electrical efficiency of 85% operates at 230 volts. For the purpose of this question, 1 hp equals 746 watts. What is the input current of this motor?
7.6 amps
Given: a 240 volt single phase circuit has a load of 10 amps. The circuit has a combined conductor length of 400 feet, (200 each way). The resistance of the conductor is 1.75 ohms per 1,000 feet. What is the power lost in this conductor
70 watts
Two incandescent lamps are connected in a series to a 120 volt source. The current through each lamp is 0.62 amps. What is the total power consumed in this circuit?
74.4 watts
Refer to the illustration. Three (3) resistance loads are feed by a 36 volt source. What is the resistance of the R1 load?
75 ohms
Given: A motor draw 4 kilowatts and delivers 4 HP. For the purposes of this question 1 HP equals 746 watts. What is the electrical efficiency of this motor?
75%
Given: A motor delivers 6.5 mechanical HP to a load. An ammeter indicates the motor is drawing 26.5 amps at 220 volts, single phase. Consider 1 HP equals 746 watts. What is the efficiency of this motor?
83%
Refer to the illustration. The switch shown is single pole. The pilot light is a neon lamp rated for 120 volts AC. The grounded connection are made up properly. There are no jumpers between screw terminals except as shown. Which figure shows the connections that will allow the pilot light to be on all the time?
A
Refer to the illustration. The switch shown is single pole. The pilot light is a neon lamp rated for 120 volts AC. The grounded connection are made up properly. There are no jumpers between screw terminals except as shown. Which figure shows the connections that will allow the pilot light to be on only when the switch is on?
B
Refer to the illustration. Which of the figures represent the 250 volt, 15 amp receptacle?
B
Refer to the illustration, What do the terminal markings H1 and H2 indicate?
Higher voltage terminals
Refer to the illustration. Pushing the button labeled 'B' will cause the motor to:
Run forward continuously
Refer to the illustration, the trouble shooting situation in the motor control circuit. When power and control voltages are applied, the motr does not start. For trouble shooting, all voltages are removed from the this circuit, none of the push buttons are depressed. None of the conductors are broken or loose from there terminals. Resistances are measured between lettered points as follows: V to W 0 ohms, W to X infinite ohms, X to Y 35 ohms, Y to Z infinite ohms. What is the problem?
an overload contact is open
the term kilowatt, indicates real power. What does the term kilovolt amp indicate?
apparent power
Refer to the illustration, the x1 and x2 markings indicates ______ terminals of the transformer?
lower voltage
Given: A single length of 300 kcmil copper conductor has a voltage drop of 3 volts and additional 300 kcmil conductor of the same length and material is connected in parallel with the original conductor. What is the total voltage drop of both these conductor connected in parallel?
1.5 volts
A non inductive heating coil in a 12 volt circuit uses 3 watts. if connected in a 24 volt circuit how much power would the coil use?
12 watts
Given: The largest available conductor for an electrical installation has resistance of 2 ohms per 1000 feet. To meet the voltage drop specification, the maximum resistance the circuit is 0.6 ohms. What is the maximum combined conductor length for the circuit?
300 feet
Refer to the illustration . The resitance of load R3 is a value between?
4.0 and 4.9 ohms
Refer to the illustration noting the connections of the meter leads as shown. Consider the following troubleshooting situation, switch S1 is in the on position but light L1 does not come on. Voltage across L1 is measured to be 120 volts, voltage across S1 is measured to be 0 volts. The light does not come on because:
the light is open ( burned out)
Refer to the illustration of the motor control circuit. What will happen if there is a short interruption of the power source supplying this circuit while the motr is running?
the motor will stop and stay stop until restarted manually
Refer to the illustration of the trouble shooting situation in the motor control circuit volts. When power and control voltages are applied the motor does not Start. When trouble shooting, all voltages are removed from this circuit, none of the push buttons are depressed. None of the conductors are broken or loose from there terminals. Resistances are measured between points as follows: V to W infinite ohms, V to X infinite ohms, X to Y 35 ohms, Y to Z 0 ohms. What is the problem?
the stop button is open
Given: A power source is obtained from three single-phase transformers connected together. each of the three hot line wires come from the x1 ends of the three transformers. The neutral wire comes from the X2 end of all three transformers. The transformer connections are _____
wye