Level 2 Module 1 Alternating Currents
A single family residence has a general lighting load of 6000 VA. What is the
minimum number of 15 A branch circuits needed? - ANSWER 4
In a series circuit, the total current is equal to the________. - ANSWER current in
any other part of the circuit
A capacitor with a capacitance of 107.6 μF is connected to a 480-V, 1000-Hz line.
How much current will flow in the circuit? - ANSWER 324
A florescent lighting bank in a commercial location operates for 8-hours per day.
Each fixture has two ballasts rated at .8 amps each. How many lights can be wired to
a 20-amp circuit breaker? - ANSWER 10
What is the ampere load of a 242.76 kVA, 3-phase, load operating at 480-V? -
ANSWER 292A
Calculate the voltage drop on 350 kcmil THHN, copper conductor supplying a 300
Ampere, single-phase load a distance of 160-ft. - ANSWER 3.5V
Luminaires in a conference room are controlled by a dimmer switch rated at 8.34
amps at 120 volts. What is the MAXIMUM wattage total connected to the switch? -
ANSWER 1,000
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. - ANSWER 333 ft
Calculate the voltage to ground for a 277/480V, 3-phase, 4-wire system. - ANSWER
227v
What is the true power of a 3 phase 480 V 200 A load with an 84% power factor? -
ANSWER 140kW
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 ½ hp motor. The new fan is rated at 120 Volts,
90% efficiency, with a ½ hp motor. What is the power savings of the new motor? -
ANSWER 11%
A 125Ω resistor is connected in parallel with a 75-ohm resistor. The voltage source is
providing 37 amps of current flow. What is the total resistance of the circuit? -
ANSWER 46.9A
The following loads are connected in series, 5Ω, 20Ω, 10Ω, and 15Ω. The voltage
total is 50-V. Find the voltage drop on the 10Ω resistor. - ANSWER 10v
, A 240V/1,600 watt resistance baseboard heater unit is installed in a construction
trailer. The contractor complains the heater unit is not working correctly. Voltage
measurements indicate the heater unit supply is 195-volts across the elements. How
much heat in watts is the heater unit producing? - ANSWER 1,056W
What is the horsepower of a motor 208V single-phase motor that draws 17.9
amperes? - ANSWER 5 HP
A home theater system requires the speakers to be protected by a fuse type
overcurrent device. The speakers are rated at 200 watts / 8-ohms. What size fuse is
required to protect each individual speaker? - ANSWER 5A
The following series circuit has resistors connected with the following values: R1=30
ohms, R2=170 ohms, R3=29.87 ohms, and R4=890 ohms. If the circuit voltage is
connected at 240V, how much total power is consumed by resistors R1 and R2 in
the circuit? - ANSWER 9.18W
A single phase 120V, 16 ampere load is connected to a 12 AWG THHN conductor.
The equipment nameplate requires no more than a 3% voltage drop on the branch
circuit. What is the maximum wire length from the panel where the voltage drop will
not exceed 3%? (K = 12.9) - ANSWER 56ft
If a single-phase electric kiln rated 5.2 amps at 240 volts is operated on 208 volts,
how much power does it consume? - ANSWER 9.6kW
How many amperes will a 35-KVA, 480 Volt three-phase generator supply to a given
three-phase load? - ANSWER 42.1A
Calculate the voltage drop on a three-phase, 480-V, branch circuit of a 1 AWG,
THW, aluminum carrying 90 amps a distance of 150-ft. - ANSWER 5.91V
Alternating current means the direction of the current flow is ______. - ANSWER
Reverses at intervals equivalent to frequency
How many 1.5 volt batteries are required to power a 13.5 volt radio and how are they
connected? - ANSWER 9 in series
The nameplate on a 3-phase 150 KVA transformer gives a primary voltage of 480V
and a secondary voltage of 208/120 V. This transformer is considered a ____
transformer. - ANSWER step-down
A non-inductive heating coil operates at 12-volts using 3-watts. If the coil is
connected to 24V, how much power will it use? - ANSWER 12 watts
The nameplate on a 3-phase 150 KVA transformer gives a primary voltage of 480V
and a secondary voltage of 347/575 V. This transformer is considered a ____
transformer. - ANSWER
A linear load heating coil operates at 24 Volts using 6 watts. If the coil is connected
to 48 Volts, how much power will it use? - ANSWER 24W
A single family residence has a general lighting load of 6000 VA. What is the
minimum number of 15 A branch circuits needed? - ANSWER 4
In a series circuit, the total current is equal to the________. - ANSWER current in
any other part of the circuit
A capacitor with a capacitance of 107.6 μF is connected to a 480-V, 1000-Hz line.
How much current will flow in the circuit? - ANSWER 324
A florescent lighting bank in a commercial location operates for 8-hours per day.
Each fixture has two ballasts rated at .8 amps each. How many lights can be wired to
a 20-amp circuit breaker? - ANSWER 10
What is the ampere load of a 242.76 kVA, 3-phase, load operating at 480-V? -
ANSWER 292A
Calculate the voltage drop on 350 kcmil THHN, copper conductor supplying a 300
Ampere, single-phase load a distance of 160-ft. - ANSWER 3.5V
Luminaires in a conference room are controlled by a dimmer switch rated at 8.34
amps at 120 volts. What is the MAXIMUM wattage total connected to the switch? -
ANSWER 1,000
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. - ANSWER 333 ft
Calculate the voltage to ground for a 277/480V, 3-phase, 4-wire system. - ANSWER
227v
What is the true power of a 3 phase 480 V 200 A load with an 84% power factor? -
ANSWER 140kW
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 ½ hp motor. The new fan is rated at 120 Volts,
90% efficiency, with a ½ hp motor. What is the power savings of the new motor? -
ANSWER 11%
A 125Ω resistor is connected in parallel with a 75-ohm resistor. The voltage source is
providing 37 amps of current flow. What is the total resistance of the circuit? -
ANSWER 46.9A
The following loads are connected in series, 5Ω, 20Ω, 10Ω, and 15Ω. The voltage
total is 50-V. Find the voltage drop on the 10Ω resistor. - ANSWER 10v
, A 240V/1,600 watt resistance baseboard heater unit is installed in a construction
trailer. The contractor complains the heater unit is not working correctly. Voltage
measurements indicate the heater unit supply is 195-volts across the elements. How
much heat in watts is the heater unit producing? - ANSWER 1,056W
What is the horsepower of a motor 208V single-phase motor that draws 17.9
amperes? - ANSWER 5 HP
A home theater system requires the speakers to be protected by a fuse type
overcurrent device. The speakers are rated at 200 watts / 8-ohms. What size fuse is
required to protect each individual speaker? - ANSWER 5A
The following series circuit has resistors connected with the following values: R1=30
ohms, R2=170 ohms, R3=29.87 ohms, and R4=890 ohms. If the circuit voltage is
connected at 240V, how much total power is consumed by resistors R1 and R2 in
the circuit? - ANSWER 9.18W
A single phase 120V, 16 ampere load is connected to a 12 AWG THHN conductor.
The equipment nameplate requires no more than a 3% voltage drop on the branch
circuit. What is the maximum wire length from the panel where the voltage drop will
not exceed 3%? (K = 12.9) - ANSWER 56ft
If a single-phase electric kiln rated 5.2 amps at 240 volts is operated on 208 volts,
how much power does it consume? - ANSWER 9.6kW
How many amperes will a 35-KVA, 480 Volt three-phase generator supply to a given
three-phase load? - ANSWER 42.1A
Calculate the voltage drop on a three-phase, 480-V, branch circuit of a 1 AWG,
THW, aluminum carrying 90 amps a distance of 150-ft. - ANSWER 5.91V
Alternating current means the direction of the current flow is ______. - ANSWER
Reverses at intervals equivalent to frequency
How many 1.5 volt batteries are required to power a 13.5 volt radio and how are they
connected? - ANSWER 9 in series
The nameplate on a 3-phase 150 KVA transformer gives a primary voltage of 480V
and a secondary voltage of 208/120 V. This transformer is considered a ____
transformer. - ANSWER step-down
A non-inductive heating coil operates at 12-volts using 3-watts. If the coil is
connected to 24V, how much power will it use? - ANSWER 12 watts
The nameplate on a 3-phase 150 KVA transformer gives a primary voltage of 480V
and a secondary voltage of 347/575 V. This transformer is considered a ____
transformer. - ANSWER
A linear load heating coil operates at 24 Volts using 6 watts. If the coil is connected
to 48 Volts, how much power will it use? - ANSWER 24W
