Electrical Code and Circuit Calculations - Residential and Commercial Systems Practice Questions & Verified Answers
How many 120-volt, 15 ampere lighting circuits are D. 9
required for a dwelling unit with a calculated light load of
16,000 volt-amperes?
The minimum size neutral conductor permitted for a B. #10 AWG
household wall-mounted oven, electric range, or cooking
unit rated 8-3/4kW or larger is _____ AWG.
Determine the minim size THWN Copper branch-circuit C. 10 AWG (8x1) + (17x1.25) =29.25A
conductors necessary for a 8-ampere noncontinuous load
and a 17-ampere continuous load.
Determine the general lighting load for a one story office B. 24,375 VA
building that measures 125 feet by 150 feet.
Only the shell for an office building is to be built. It is 225 D. 465,750 VA 225x90=20,250x2.3x10=465,750
feet long, 90 feet wide, and 10 stories high. Calculate the
lighting and receptacle feeder demand in volt-amperes for
the building with the number of receptacles unknown.
An appliance store has 32 feet of multioutlet assembly. B. 1,260 VA 32/5=6.4 = 7x180
Calculate the volt-ampere load for only light use of the
multioutlet assembly.
The service to a multistory building is 277/480-volt, 3- A. 22.5kVA
phase, 4-wire. There are 125 120-volt, duplex, general-
purpose receptacles to be installed on each floor. A 3-
phase, 480-volt primary, 120/208-volt secondary
transformer is to be installed on each floor to supply the
receptacles. Calculate the transformer secondary kilovolt-
ampere (kVA) devoted to only the general-purpose
receptacle load.
Each unit of a 12-unit multifamily dwelling is 2,000 square C. 4
feet and supplied by a 120/240-volt, 3 wire system.
Calculate the number of 15-ampere lighting branch circuits
required in each unit.
Calculate the general lighting load for a 2,500 square foot, D. 7,500VA 2500x3
one family dwelling
A multifamily complex has 30 units with a 120/240-volt, B. 56,700 VA
6kW dryer in each unit. What is the dryer load feeder
demand for the ungrounded conductors of this complex?
The plans for a one-family dwelling show that a five- C. 6,720 VA
horsepower, 240-volt, single-phase air conditioning unit
and a five-kilowatt fixed electric space heater are to be
installed using the same feeder circuit. Calculate each load
and determine which single load will be used for the feeder
demand. (Hint: The Code refers to these loads as
noncoincidental loads.)
A fixed appliance (non-motor operated) in an industrial C. 35A
building is rated at 28 amperes, and is supplied by an
individual branch circuit. The load is continuous, and the
branch-circuit device is not rated for continuous loading at
100% of its rating. Determine the minimum standard size
branch circuit required to supply this appliance.
Stuvia 2026-2027
,Electrical Code and Circuit Calculations - Residential and Commercial Systems Practice Questions & Verified Answers
Two lengths of industrial infrared heating equipment are D. 30A
installed on a common branch circuit. Each piece of
baseboard is rated at 240 volts and 11 amperes.
Determine the minimum standard size overcurrent
protective device required to serve this load.
Calculate the resistance of 175 feet of 14 AWG stranded B. 0.55 ohms
uncoated copper conductor.
An 8 AWG stranded conductor is somewhat larger in B. 0.018 in.
diameter than a solid conductor of the same size. How
much larger is the diameter of an 8 AWG stranded
conductor than that of an 8 AWG solid conductor?
Calculate the resistance of 150 feet of 14 AWG THWN C. 0.461 ohms
solid uncoated copper conductor.
Calculate the resistance of 250 feet of 6 AWG THHN A. 0.212 ohms
aluminum conductor.
Which IEC standard programming language most closely C. Ladder logic
replicates the control diagrams used in traditional magnetic
motor control?
PLC programming is performed by ? or by a personal B. a handheld programmer
computer connected directly to the processor or through a
network connection.
Devices, such as switches and sensors, motor starters, B. Field
pilot lights, and solenoid valves, connected to a PLC are
identified as ? devices, indicating that they are not part of
the PLC hardware.
In a fixed and modular PLC, ? interfaces provide the link B. Output
between the PLC and external devices such as lamps,
motor starters, and solenoids.
Modular PLC discrete output modules are available with A. Relay Contacts
solid state AC, solid state DC, and ? type outputs.
One 10kW range, one 19 kW, and one 24 kW range are to C. 18,200 VA
be installed in a multifamily dwelling. What is the feeder
demand for the three household ranges for the
ungrounded conductors only?
What is the minimum ungrounded conductor(s) feeder A. 4,500 VA
demand for two 3 kW household electric ovens in a
dwelling unit?
What minimum size aluminum wire is needed for a 440- C. 2 AWG
volt, 3-phase branch circuit supplying a 60-ampere load at
a distance of 325 feet and holding the voltage drop within
a reasonable limit of efficiency?
? overload relays offer greater flexibility and quicker reset Magnetic / Thermal
times than ? overloads because no heat is required for
operation.
Stuvia 2026-2027
, Electrical Code and Circuit Calculations - Residential and Commercial Systems Practice Questions & Verified Answers
Class 1 power-limited circuits shall be supplied from a D. 1000 VA
source that has a rated output of not more than 30 volts
and ______.
A 15-kV electrical switchboard is installed on a 13.8Y/8-kV C. 4'
distribution system in an industrial establishment in such
way that there are guarded live parts on both sides of the
work space. What is the minimum depth of clear working
space required for this installation?
Programmable ? timers can emulate a seven-day time C. Real time clock
clock?
? is a reduced voltage starting technique that connects a C. Primary resistor starting
resistor in series with each phase supplying the motor.
Tachometer and encoder are two devices that are used to B. Speed
monitor the ? of the motor.
Which is used when determining the receptacle load for a D. The larger of 1 VA per ft2 or 180 VA per receptacle.
commercial office building?
What is the minimum required load for either one of the 20- A. 1500 VA
ampere small appliance branch circuits or the 20-ampere
laundry circuit?
Dynamic, flux, injection, and regenerative are four types of A. Electrical
? braking techniques.
When analog control devices are located large distances A. Current
from each other, which type of signal is preferable for
installing the control wiring?
What is the ampactiy of the the ungrounded feeder C. 1300
conductors with a calculated 312 kVA load, when the
series is 120/240 volt, single-phase, 3-wire?
Resistance temperature detectors (RTDs) and D. Temperature
thermocouples are typical of analog sensing devices that
measure ? in a process.
A ? is a magnetically activated switching device (without B. Magnetic contactor
overload protection attached) and is used to switch single-
phase or three-phase AC power, or DC power to the load.
Exhaust fans, small drill presses, and commercial garbage D. Manual motor starters
disposals are some common examples of typical fractional
horsepower motors that would be controlled by ?.
Generally, control transformers step down the main line A. 120 VAC/24 VAC
voltage to a control voltage of ? or ?.
Which of the following wiring methods is not permitted for D. Type AC cable
above-ground service-entrance conductors rated 1,000
volts nominal or greater?
Stuvia 2026-2027
How many 120-volt, 15 ampere lighting circuits are D. 9
required for a dwelling unit with a calculated light load of
16,000 volt-amperes?
The minimum size neutral conductor permitted for a B. #10 AWG
household wall-mounted oven, electric range, or cooking
unit rated 8-3/4kW or larger is _____ AWG.
Determine the minim size THWN Copper branch-circuit C. 10 AWG (8x1) + (17x1.25) =29.25A
conductors necessary for a 8-ampere noncontinuous load
and a 17-ampere continuous load.
Determine the general lighting load for a one story office B. 24,375 VA
building that measures 125 feet by 150 feet.
Only the shell for an office building is to be built. It is 225 D. 465,750 VA 225x90=20,250x2.3x10=465,750
feet long, 90 feet wide, and 10 stories high. Calculate the
lighting and receptacle feeder demand in volt-amperes for
the building with the number of receptacles unknown.
An appliance store has 32 feet of multioutlet assembly. B. 1,260 VA 32/5=6.4 = 7x180
Calculate the volt-ampere load for only light use of the
multioutlet assembly.
The service to a multistory building is 277/480-volt, 3- A. 22.5kVA
phase, 4-wire. There are 125 120-volt, duplex, general-
purpose receptacles to be installed on each floor. A 3-
phase, 480-volt primary, 120/208-volt secondary
transformer is to be installed on each floor to supply the
receptacles. Calculate the transformer secondary kilovolt-
ampere (kVA) devoted to only the general-purpose
receptacle load.
Each unit of a 12-unit multifamily dwelling is 2,000 square C. 4
feet and supplied by a 120/240-volt, 3 wire system.
Calculate the number of 15-ampere lighting branch circuits
required in each unit.
Calculate the general lighting load for a 2,500 square foot, D. 7,500VA 2500x3
one family dwelling
A multifamily complex has 30 units with a 120/240-volt, B. 56,700 VA
6kW dryer in each unit. What is the dryer load feeder
demand for the ungrounded conductors of this complex?
The plans for a one-family dwelling show that a five- C. 6,720 VA
horsepower, 240-volt, single-phase air conditioning unit
and a five-kilowatt fixed electric space heater are to be
installed using the same feeder circuit. Calculate each load
and determine which single load will be used for the feeder
demand. (Hint: The Code refers to these loads as
noncoincidental loads.)
A fixed appliance (non-motor operated) in an industrial C. 35A
building is rated at 28 amperes, and is supplied by an
individual branch circuit. The load is continuous, and the
branch-circuit device is not rated for continuous loading at
100% of its rating. Determine the minimum standard size
branch circuit required to supply this appliance.
Stuvia 2026-2027
,Electrical Code and Circuit Calculations - Residential and Commercial Systems Practice Questions & Verified Answers
Two lengths of industrial infrared heating equipment are D. 30A
installed on a common branch circuit. Each piece of
baseboard is rated at 240 volts and 11 amperes.
Determine the minimum standard size overcurrent
protective device required to serve this load.
Calculate the resistance of 175 feet of 14 AWG stranded B. 0.55 ohms
uncoated copper conductor.
An 8 AWG stranded conductor is somewhat larger in B. 0.018 in.
diameter than a solid conductor of the same size. How
much larger is the diameter of an 8 AWG stranded
conductor than that of an 8 AWG solid conductor?
Calculate the resistance of 150 feet of 14 AWG THWN C. 0.461 ohms
solid uncoated copper conductor.
Calculate the resistance of 250 feet of 6 AWG THHN A. 0.212 ohms
aluminum conductor.
Which IEC standard programming language most closely C. Ladder logic
replicates the control diagrams used in traditional magnetic
motor control?
PLC programming is performed by ? or by a personal B. a handheld programmer
computer connected directly to the processor or through a
network connection.
Devices, such as switches and sensors, motor starters, B. Field
pilot lights, and solenoid valves, connected to a PLC are
identified as ? devices, indicating that they are not part of
the PLC hardware.
In a fixed and modular PLC, ? interfaces provide the link B. Output
between the PLC and external devices such as lamps,
motor starters, and solenoids.
Modular PLC discrete output modules are available with A. Relay Contacts
solid state AC, solid state DC, and ? type outputs.
One 10kW range, one 19 kW, and one 24 kW range are to C. 18,200 VA
be installed in a multifamily dwelling. What is the feeder
demand for the three household ranges for the
ungrounded conductors only?
What is the minimum ungrounded conductor(s) feeder A. 4,500 VA
demand for two 3 kW household electric ovens in a
dwelling unit?
What minimum size aluminum wire is needed for a 440- C. 2 AWG
volt, 3-phase branch circuit supplying a 60-ampere load at
a distance of 325 feet and holding the voltage drop within
a reasonable limit of efficiency?
? overload relays offer greater flexibility and quicker reset Magnetic / Thermal
times than ? overloads because no heat is required for
operation.
Stuvia 2026-2027
, Electrical Code and Circuit Calculations - Residential and Commercial Systems Practice Questions & Verified Answers
Class 1 power-limited circuits shall be supplied from a D. 1000 VA
source that has a rated output of not more than 30 volts
and ______.
A 15-kV electrical switchboard is installed on a 13.8Y/8-kV C. 4'
distribution system in an industrial establishment in such
way that there are guarded live parts on both sides of the
work space. What is the minimum depth of clear working
space required for this installation?
Programmable ? timers can emulate a seven-day time C. Real time clock
clock?
? is a reduced voltage starting technique that connects a C. Primary resistor starting
resistor in series with each phase supplying the motor.
Tachometer and encoder are two devices that are used to B. Speed
monitor the ? of the motor.
Which is used when determining the receptacle load for a D. The larger of 1 VA per ft2 or 180 VA per receptacle.
commercial office building?
What is the minimum required load for either one of the 20- A. 1500 VA
ampere small appliance branch circuits or the 20-ampere
laundry circuit?
Dynamic, flux, injection, and regenerative are four types of A. Electrical
? braking techniques.
When analog control devices are located large distances A. Current
from each other, which type of signal is preferable for
installing the control wiring?
What is the ampactiy of the the ungrounded feeder C. 1300
conductors with a calculated 312 kVA load, when the
series is 120/240 volt, single-phase, 3-wire?
Resistance temperature detectors (RTDs) and D. Temperature
thermocouples are typical of analog sensing devices that
measure ? in a process.
A ? is a magnetically activated switching device (without B. Magnetic contactor
overload protection attached) and is used to switch single-
phase or three-phase AC power, or DC power to the load.
Exhaust fans, small drill presses, and commercial garbage D. Manual motor starters
disposals are some common examples of typical fractional
horsepower motors that would be controlled by ?.
Generally, control transformers step down the main line A. 120 VAC/24 VAC
voltage to a control voltage of ? or ?.
Which of the following wiring methods is not permitted for D. Type AC cable
above-ground service-entrance conductors rated 1,000
volts nominal or greater?
Stuvia 2026-2027
