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AZ ROC R-11 Electrical practice questions

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Question 1Electrical Systems and General Electrical Knowledge

A 120-volt branch circuit has a total resistance of 24 ohms. What current does the circuit draw?

  1. 5 A Correct answer.
  2. 0.2 A
  3. 20 A
  4. 2,880 A

Explanation

Ohm's law states that current equals voltage divided by resistance. Dividing 120 volts by 24 ohms gives 5 amperes. This relationship holds for any purely resistive branch circuit.

Question 2Electrical Systems and General Electrical Knowledge

Two resistors of 10 ohms and 20 ohms are connected in series across a 60-volt source. What current flows in the circuit?

  1. 6 A
  2. 2 A Correct answer.
  3. 3 A
  4. 0.5 A

Explanation

In a series circuit the resistances add, so the total is 30 ohms. Applying Ohm's law, 60 volts divided by 30 ohms equals 2 amperes. The same current passes through every element of a series circuit.

Question 3Electrical Systems and General Electrical Knowledge

Two 12-ohm resistors are connected in parallel. What is the equivalent resistance of the combination?

  1. 24 ohms
  2. 6 ohms Correct answer.
  3. 3 ohms
  4. 12 ohms

Explanation

For two equal resistors in parallel, the equivalent resistance is half the value of one resistor. Twelve ohms divided by two is 6 ohms, which is also confirmed by the product-over-sum formula.

Question 4Electrical Systems and General Electrical Knowledge

A 120-volt circuit carries 15 amperes to a resistive load. How much power does the load consume?

  1. 1,050 W
  2. 135 W
  3. 8 W
  4. 1,800 W Correct answer.

Explanation

For a resistive load, power in watts equals voltage multiplied by current. Multiplying 120 volts by 15 amperes gives 1,800 watts. The same result follows from squaring the current and multiplying by resistance.

Question 5Electrical Systems and General Electrical Knowledge

Which conductor color identifies the grounded conductor of a branch circuit?

  1. Blue or orange
  2. White or gray Correct answer.
  3. Black or red
  4. Green

Explanation

The NEC requires the grounded conductor of a circuit to be identified by a continuous white or gray finish. Green is reserved for equipment grounding conductors. Ungrounded phase conductors are typically black, red, or blue.

Question 6Electrical Systems and General Electrical Knowledge

In a dwelling unit, receptacle outlets in which of the following rooms require GFCI protection?

  1. Bathroom Correct answer.
  2. Dining room
  3. Bedroom
  4. Living room

Explanation

The NEC requires ground-fault circuit-interrupter protection for all 125-volt receptacle outlets in dwelling-unit bathrooms. Protection is also required in other wet or damp locations such as kitchens, garages, and outdoors. GFCI devices trip when current imbalance to ground reaches the threshold.

Question 7Electrical Systems and General Electrical Knowledge

What is the function of the equipment grounding conductor in a branch circuit?

  1. Carries normal load current
  2. Reduces starting current for motors
  3. Balances voltage between phases
  4. Provides a low-impedance fault current path Correct answer.

Explanation

The equipment grounding conductor bonds metal enclosures and equipment to the system grounding point. If a fault energizes the metal, the conductor provides a low-impedance path that allows a large fault current to flow. That current quickly operates the overcurrent device and de-energizes the circuit.

Question 8Electrical Systems and General Electrical Knowledge

What does an arc-fault circuit interrupter detect?

  1. Arcing in branch-circuit wiring Correct answer.
  2. Overload current in the neutral
  3. Current imbalance to ground
  4. Voltage spikes on the service

Explanation

An arc-fault circuit interrupter monitors the waveform of the branch circuit and recognizes the signature of a dangerous parallel or series arc. It opens the circuit to prevent ignition of surrounding materials. Current imbalance to ground is the sensing principle of a GFCI instead.

Question 9Electrical Systems and General Electrical Knowledge

When a raceway contains three or more current-carrying conductors, what is the maximum permitted fill?

  1. 53 percent
  2. 40 percent Correct answer.
  3. 60 percent
  4. 31 percent

Explanation

The NEC conduit fill table permits 53 percent fill for a single conductor, 31 percent for two conductors, and 40 percent for three or more conductors. The 40 percent limit is intended to allow pulling without damaging insulation.

Question 10Electrical Systems and General Electrical Knowledge

How much box volume must be provided for each 12 AWG conductor in a box?

  1. 2.00 cubic inches
  2. 2.25 cubic inches Correct answer.
  3. 3.00 cubic inches
  4. 2.50 cubic inches

Explanation

The box fill table assigns a volume allowance based on conductor size. Each 12 AWG conductor requires 2.25 cubic inches, while 14 AWG requires 2.00 and 10 AWG requires 2.50. Device yokes, clamps, and equipment grounding conductors add additional allowances.

Question 11Electrical Systems and General Electrical Knowledge

A 120-volt circuit supplies 16 amperes over conductors whose combined resistance is 0.5 ohm. What is the voltage drop on the circuit?

  1. 16 V
  2. 4 V
  3. 2 V
  4. 8 V Correct answer.

Explanation

Voltage drop equals current multiplied by the total conductor resistance. Multiplying 16 amperes by 0.5 ohm gives 8 volts of drop. The load therefore sees approximately 112 volts.

Question 12Electrical Systems and General Electrical Knowledge

For equipment operating at 151 to 600 volts to ground, what is the minimum depth of the working space in front of the equipment under Condition 1?

  1. 2 feet
  2. 2.5 feet
  3. 3.5 feet Correct answer.
  4. 3 feet

Explanation

The working space depth table requires 3 feet for equipment operating at 0 to 150 volts to ground and 3.5 feet for equipment at 151 to 600 volts to ground under Condition 1. Greater depths apply under Conditions 2 and 3 where exposed live parts exist on the opposite side.

Question 13Electrical Systems and General Electrical Knowledge

Where must the service disconnecting means be located?

  1. At the farthest branch panel
  2. Nearest the service entry point Correct answer.
  3. Inside the utility transformer
  4. At each individual outlet

Explanation

The service disconnecting means must be installed at a readily accessible location, either inside or outside the building, nearest the point where the service conductors enter. This limits the length of unprotected service conductors inside the structure.

Question 14Electrical Systems and General Electrical Knowledge

What is the minimum width of the working space in front of electrical equipment?

  1. 24 inches
  2. 36 inches
  3. 30 inches Correct answer.
  4. 42 inches

Explanation

The working space in front of electrical equipment must be at least 30 inches wide, or the width of the equipment if it is wider. The space must extend from the floor to a height of 6.5 feet. The depth requirement is separate and depends on voltage and conditions.

Question 15Electrical Systems and General Electrical Knowledge

In a three-way switching circuit, how many traveler conductors run between the two switches?

  1. Two Correct answer.
  2. One
  3. Four
  4. Three

Explanation

A three-way switch has one common terminal and two traveler terminals. Two traveler conductors connect the travelers of the two switches so either switch can complete the circuit. The common terminals connect to the source and to the load.

Question 16Electrical Systems and General Electrical Knowledge

What is the ampacity of 12 AWG copper conductors with 60°C-rated insulation?

  1. 20 A Correct answer.
  2. 30 A
  3. 25 A
  4. 15 A

Explanation

The ampacity table lists 12 AWG copper at 20 amperes for the 60°C column. Higher-temperature insulation columns allow more current, but the termination rating often limits the usable ampacity. Ambient temperature and conductor bundling adjustments are applied afterward.

Question 17Electrical Systems and General Electrical Knowledge

A motor branch circuit has both overload relays and a branch-circuit short-circuit protective device. What do the overload relays primarily protect the motor against?

  1. Sustained overloads Correct answer.
  2. Lightning surges
  3. Short circuits
  4. Ground faults

Explanation

Overload relays are sized close to the motor's running current and are intended to open the circuit after a sustained overload that would overheat the windings. Short circuits and grounds are cleared by the branch-circuit protective device. The two functions are deliberately separate because motors draw high starting current.

Question 18Electrical Systems and General Electrical Knowledge

A transformer has 200 turns on its primary and 50 turns on its secondary. If the primary is supplied at 480 volts, what is the secondary voltage?

  1. 240 V
  2. 1,920 V
  3. 60 V
  4. 120 V Correct answer.

Explanation

The voltage ratio of a transformer equals the turns ratio. Here the ratio is 200 to 50, or 4 to 1, so the secondary voltage is 480 divided by 4, which is 120 volts. A step-down turns ratio produces a step-down voltage.

Question 19Electrical Systems and General Electrical Knowledge

A conductor has a 75°C ampacity of 50 amperes. It is installed where the ambient temperature correction factor is 0.82. What is the corrected ampacity?

  1. 45 A
  2. 41 A Correct answer.
  3. 30 A
  4. 61 A

Explanation

Ambient temperature correction is applied by multiplying the table ampacity by the correction factor. Multiplying 50 amperes by 0.82 gives 41 amperes. The corrected value must still be at least the load current plus any required margin.

Question 20Electrical Systems and General Electrical Knowledge

In a dwelling unit, receptacles along a wall must be spaced so that no point on the wall line is more than what distance from a receptacle outlet?

  1. 3 feet
  2. 4 feet
  3. 6 feet Correct answer.
  4. 5 feet

Explanation

Receptacle outlets must be installed so that no point along the floor line of any wall space is more than 6 feet from an outlet. This spacing rule, together with the requirement for outlets in wall spaces 2 feet or wider, keeps appliance cords within reach. The distance is measured along the floor line, not in a straight line through the room.

Question 21Electrical Systems and General Electrical Knowledge

Which statement correctly distinguishes bonding from grounding?

  1. Grounding joins metal parts; bonding connects to earth
  2. Bonding joins metal parts; grounding connects to earth Correct answer.
  3. Both terms apply only to service equipment
  4. Both terms describe only earth connections

Explanation

Bonding is the electrical interconnection of metal parts so they remain at the same potential, while grounding is the connection of the electrical system to the earth. Bonding is what makes the fault-current path effective; grounding stabilizes voltage to earth. The two concepts work together but are not interchangeable.

Question 22Electrical Systems and General Electrical Knowledge

A balanced 208-volt, three-phase load draws 30 amperes per phase. What is the apparent power?

  1. 18.0 kVA
  2. 10.8 kVA Correct answer.
  3. 6.2 kVA
  4. 9.0 kVA

Explanation

For a balanced three-phase load, apparent power equals the square root of three multiplied by line voltage and line current. Multiplying 1.732 by 208 volts by 30 amperes gives about 10,809 volt-amperes, or roughly 10.8 kVA. Multiplying voltage by current alone would understate the load.

Question 23Electrical Systems and General Electrical Knowledge

What is the primary function of a circuit breaker in a branch circuit?

  1. Balances the load between phases
  2. Converts AC to DC for the load
  3. Regulates voltage to the load
  4. Opens the circuit on overcurrent Correct answer.

Explanation

A circuit breaker is an overcurrent protective device that opens automatically when current exceeds its rating for a set time. It protects conductors and equipment from overloads and short circuits. Voltage regulation and power conversion are separate functions performed by other equipment.

Question 24Electrical Systems and General Electrical Knowledge

How is a grounding-type receptacle identified?

  1. Two angled slots
  2. Two parallel flat slots
  3. A single T-shaped slot
  4. A grounding hole Correct answer.

Explanation

A grounding-type receptacle has a round or U-shaped opening in addition to the two current-carrying slots. The grounding contact connects the equipment grounding conductor to the cord's grounding pin. Receptacles without that opening are non-grounding types.

Question 25Electrical Systems and General Electrical Knowledge

When circuit conductors are installed in parallel, what is the minimum permitted size for each conductor?

  1. 1/0 AWG Correct answer.
  2. 2 AWG
  3. 4 AWG
  4. 6 AWG

Explanation

The NEC generally requires that conductors installed in parallel be 1/0 AWG or larger, with limited exceptions for smaller conductors in specific applications. The rule ensures that current divides predictably among the parallel runs. All parallel conductors must also be the same length, material, and size.

Question 26Electrical Systems and General Electrical Knowledge

Which insulation color is permitted for the grounded conductor of a branch circuit?

  1. Black or red
  2. Bare copper
  3. White or gray Correct answer.
  4. Green

Explanation

Section 200.6 requires the grounded conductor to be identified by a continuous white or gray outer finish along its entire length. Green and bare copper identify equipment grounding conductors, while black and red are used for ungrounded conductors.

Question 27Electrical Systems and General Electrical Knowledge

A Class A ground-fault circuit interrupter is designed to trip at a ground-fault current in what range?

  1. 15 to 20 milliamperes
  2. 4 to 6 milliamperes Correct answer.
  3. 0.5 to 1 milliampere
  4. 100 to 300 milliamperes

Explanation

A Class A GFCI is required to interrupt the circuit when a ground-fault current of 4 to 6 milliamperes occurs. This low threshold is intended to protect people from electric shock. Higher thresholds describe other protective devices or equipment leakage levels.

Question 28Electrical Systems and General Electrical Knowledge

In a series circuit, which quantity is the same through every component?

  1. Voltage
  2. Resistance
  3. Current Correct answer.
  4. Power

Explanation

A series circuit provides only one path for current, so the same current flows through each component. The source voltage divides among the components according to their resistances, and power dissipated differs with each resistance.

Question 29Electrical Systems and General Electrical Knowledge

What is the minimum length of a ground rod electrode permitted to be used?

  1. 10 feet
  2. 4 feet
  3. 8 feet Correct answer.
  4. 6 feet

Explanation

A ground rod must be at least 8 feet in length and at least 5/8 inch in diameter unless listed otherwise. Rods shorter than 8 feet do not meet the minimum electrode length requirement.

Question 30Electrical Systems and General Electrical Knowledge

A conductor has an ampacity of 78 amperes. The circuit is not a multioutlet branch circuit supplying receptacles, and the load does not exceed 78 amperes. What is the maximum standard circuit-breaker rating permitted to protect this conductor?

  1. 80 amperes Correct answer.
  2. 70 amperes
  3. 90 amperes
  4. 100 amperes

Explanation

The next-higher-standard-overcurrent-device rule permits the next standard rating above the conductor ampacity when the circuit is not a multioutlet receptacle branch circuit and the load does not exceed the conductor ampacity. The next standard rating above 78 amperes is 80 amperes.

Question 31Electrical Systems and General Electrical Knowledge

A single-phase motor has a full-load current of 20 amperes. Using the general rule of Table 430.52, what is the maximum rating of an inverse-time circuit breaker permitted for branch-circuit short-circuit and ground-fault protection?

  1. 40 amperes
  2. 60 amperes
  3. 50 amperes Correct answer.
  4. 30 amperes

Explanation

Table 430.52 generally permits an inverse-time circuit breaker sized at 250 percent of the motor full-load current for short-circuit and ground-fault protection. For a 20-ampere full-load current, 250 percent equals 50 amperes.

Question 32Electrical Systems and General Electrical Knowledge

A 100-ampere overcurrent device protects a feeder with copper conductors. What is the minimum size copper equipment grounding conductor required?

  1. 10 AWG
  2. 8 AWG Correct answer.
  3. 6 AWG
  4. 12 AWG

Explanation

Table 250.122 sizes the equipment grounding conductor according to the rating of the overcurrent device protecting the circuit. For a 100-ampere overcurrent device, the minimum copper equipment grounding conductor is 8 AWG.

Question 33Electrical Systems and General Electrical Knowledge

What is the minimum height of the working space in front of electrical equipment, measured from the floor or platform?

  1. 6 feet 3 inches
  2. 6 feet 6 inches Correct answer.
  3. 6 feet
  4. 5 feet

Explanation

The working space in front of electrical equipment must be at least 6 feet 6 inches high, or the height of the equipment if greater. This headroom requirement ensures safe access and movement while working on energized equipment.

Question 34Electrical Systems and General Electrical Knowledge

How often must nonmetallic-sheathed cable be secured along its run?

  1. At intervals not exceeding 6 feet and within 12 inches of each box
  2. At intervals not exceeding 8 feet and within 18 inches of each box
  3. At intervals not exceeding 4.5 feet and within 12 inches of each box Correct answer.
  4. At intervals not exceeding 3 feet and within 6 inches of each box

Explanation

Nonmetallic-sheathed cable must be secured at intervals not exceeding 4.5 feet and within 12 inches of every box or fitting. These support intervals keep the cable from sagging and protect it from damage.

Question 35Electrical Systems and General Electrical Knowledge

What total voltage drop is recommended for a branch circuit plus feeder combined?

  1. 2 percent
  2. 10 percent
  3. 3 percent
  4. 5 percent Correct answer.

Explanation

The recommended maximum total voltage drop for a feeder plus branch circuit is 5 percent. Individual branch circuits are recommended to be limited to 3 percent, leaving the remainder for the feeder.

Question 36Electrical Systems and General Electrical Knowledge

A 120-volt single-phase load draws 10 amperes at a power factor of 0.80. What is the real power consumed by the load?

  1. 960 watts Correct answer.
  2. 1500 watts
  3. 1200 watts
  4. 768 watts

Explanation

Real power equals voltage times current times power factor: 120 volts times 10 amperes times 0.80 equals 960 watts. The 1200 volt-ampere product is apparent power, not real power.

Question 37Electrical Systems and General Electrical Knowledge

In a 208Y/120-volt, three-phase, four-wire system, what is the nominal voltage between any one phase conductor and the neutral?

  1. 120 volts Correct answer.
  2. 208 volts
  3. 360 volts
  4. 104 volts

Explanation

In a wye-connected system, the line-to-neutral voltage equals the line-to-line voltage divided by the square root of three. Dividing 208 volts by 1.732 gives approximately 120 volts.

Question 38Electrical Systems and General Electrical Knowledge

Two 6-ohm resistors are connected in parallel, and that parallel pair is connected in series with a 4-ohm resistor. What is the total resistance of the circuit?

  1. 10 ohms
  2. 4 ohms
  3. 16 ohms
  4. 7 ohms Correct answer.

Explanation

Two equal 6-ohm resistors in parallel have an equivalent resistance of 3 ohms. Adding the series 4-ohm resistor gives a total resistance of 7 ohms.

Question 39Electrical Systems and General Electrical Knowledge

A balanced 480-volt, three-phase load draws 20 amperes per phase at a power factor of 0.85. What is the real power drawn by the load?

  1. 24.0 kilowatts
  2. 14.1 kilowatts Correct answer.
  3. 16.6 kilowatts
  4. 9.4 kilowatts

Explanation

For a balanced three-phase load, real power equals the square root of three times line voltage times line current times power factor. Multiplying 1.732 by 480 volts by 20 amperes by 0.85 gives approximately 14,100 watts, or 14.1 kilowatts.

Question 40Electrical Systems and General Electrical Knowledge

A sinusoidal AC voltage has an RMS value of 120 volts. What is its peak value?

  1. 120 volts
  2. 84.9 volts
  3. 240 volts
  4. 170 volts Correct answer.

Explanation

For a sine wave, the peak value equals the RMS value multiplied by the square root of two, about 1.414. Multiplying 120 volts by 1.414 gives approximately 170 volts.

Question 41Wiring Methods, Materials, and Installations

How often must Type NM cable be secured along its run, in addition to being secured within 12 inches of each box?

  1. Every 8 feet
  2. Every 6 feet
  3. Every 4 1/2 feet Correct answer.
  4. Every 10 feet

Explanation

Section 334.30 requires Type NM cable to be supported and secured at intervals not exceeding 4 1/2 feet and within 12 inches of every box or fitting. This support keeps the cable from sagging and helps protect it from damage.

Question 42Wiring Methods, Materials, and Installations

In box-fill calculations, how much volume is counted for each 14 AWG conductor?

  1. 2.00 cubic inches Correct answer.
  2. 1.50 cubic inches
  3. 2.25 cubic inches
  4. 2.50 cubic inches

Explanation

Table 314.16(B) assigns 2.00 cubic inches to each 14 AWG conductor. The values increase with conductor size, such as 2.25 cubic inches for 12 AWG and 2.50 cubic inches for 10 AWG.

Question 43Wiring Methods, Materials, and Installations

In a dwelling unit, receptacles must be installed so that no point along the floor line of a wall is more than what distance from a receptacle?

  1. 4 feet
  2. 6 feet
  3. 12 feet
  4. 8 feet Correct answer.

Explanation

Section 210.52(A)(1) requires receptacle outlets along wall space so that no point is more than 6 feet from a receptacle. This is why receptacles are commonly spaced no more than 12 feet apart along a wall.

Question 44Wiring Methods, Materials, and Installations

Which dwelling-unit location requires GFCI protection for its 125-volt receptacle outlets?

  1. Living room
  2. Dining room
  3. Bedroom
  4. Bathroom Correct answer.

Explanation

Section 210.8(A) requires GFCI protection for receptacles in bathrooms, garages, outdoors, kitchens, laundry areas, unfinished basements, and other listed locations. Bathrooms are specifically included.

Question 45Wiring Methods, Materials, and Installations

The grounded conductor of a branch circuit must be identified by which color?

  1. Green
  2. Black
  3. White Correct answer.
  4. Red

Explanation

Section 200.6 requires the grounded conductor to be identified by a continuous white or gray finish. Green is reserved for equipment grounding conductors, while black and red are commonly used for ungrounded conductors.

Question 46Wiring Methods, Materials, and Installations

Where Type NM cable passes through a bored hole in a wood stud, steel protection is required when the cable is within what distance of the nearest edge of the hole?

  1. 1 1/4 inches Correct answer.
  2. 1 1/2 inches
  3. 1 inch
  4. 2 inches

Explanation

Section 300.4(A)(1) requires protection where a hole in wood framing is less than 1 1/4 inches from the nearest edge. A steel plate or bushing prevents nails or screws from damaging the cable.

Question 47Wiring Methods, Materials, and Installations

What is the minimum earth cover required for Type UF cable buried directly in the ground?

  1. 30 inches
  2. 12 inches
  3. 18 inches
  4. 24 inches Correct answer.

Explanation

Table 300.5 requires a minimum cover of 24 inches for direct-buried cables. The greater depth protects the cable from damage caused by digging and surface loads.

Question 48Wiring Methods, Materials, and Installations

What is the maximum total bend, in degrees, permitted in a run of conduit between pull points?

  1. 450 degrees
  2. 360 degrees Correct answer.
  3. 270 degrees
  4. 180 degrees

Explanation

Section 358.26 and related raceway rules limit bends between pull points to a total of 360 degrees. This limit allows conductors to be pulled without excessive friction or damage.

Question 49Wiring Methods, Materials, and Installations

A 4-inch by 4-inch by 2 1/8-inch box contains four 12 AWG circuit conductors, two 12 AWG equipment grounding conductors, one cable clamp, and one single receptacle. What minimum box volume does this installation require?

  1. 15.75 cubic inches
  2. 18.0 cubic inches Correct answer.
  3. 20.25 cubic inches
  4. 22.5 cubic inches

Explanation

Each 12 AWG conductor counts as 2.25 cubic inches. Four circuit conductors count as 9.0 cubic inches, all equipment grounding conductors together count as one conductor at 2.25 cubic inches, the clamp counts as one conductor, and the single receptacle counts as two conductors; the total is 18.0 cubic inches.

Question 50Wiring Methods, Materials, and Installations

On a dwelling-unit kitchen countertop, what is the maximum distance from any point along the counter wall to a receptacle outlet?

  1. 48 inches
  2. 36 inches
  3. 12 inches
  4. 24 inches Correct answer.

Explanation

Section 210.52(C)(1) requires countertop receptacles so that no point along the counter wall line is more than 24 inches from a receptacle. This spacing reduces the need for extension cords on kitchen counters.