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MI Journeyman Electrician practice questions

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Question 1General Electrical Knowledge and Code Administration

What is the stated purpose of the National Electrical Code?

  1. To guarantee efficient operation of electrical systems
  2. To establish the rates utilities may charge for power
  3. To prescribe manufacturing standards for electrical products
  4. To safeguard persons and property from electrical hazards Correct answer.

Explanation

The Code exists for the practical safeguarding of persons and property from hazards arising from the use of electricity. It is an installation code, not a design manual, a product standard, or a rate schedule.

Question 2General Electrical Knowledge and Code Administration

Ampacity is best described as which of the following?

  1. The continuous current its temperature rating allows Correct answer.
  2. The voltage at which the insulation is rated
  3. The current at which the overcurrent device trips
  4. The short-circuit withstand rating of the conductor

Explanation

Ampacity is the current a conductor can carry continuously under the conditions of use without exceeding its temperature rating. Insulation life and termination limits are both governed by that temperature.

Question 3General Electrical Knowledge and Code Administration

The working space in front of electrical equipment must have a minimum width of which of the following?

  1. 30 in. or the width of the equipment, whichever is greater Correct answer.
  2. 42 in. measured outward from the equipment centerline
  3. 24 in. or the width of the equipment, whichever is greater
  4. 36 in. regardless of the width of the equipment

Explanation

The clear working space must be at least 30 in. wide, or the width of the equipment if that is greater, and it must extend from the floor to the required headroom.

Question 4General Electrical Knowledge and Code Administration

A 125-volt, 20-ampere receptacle installed in a dwelling-unit bathroom must be which of the following?

  1. Installed within 12 inches of the floor
  2. Protected by a ground-fault circuit interrupter Correct answer.
  3. Connected to the small-appliance branch circuit
  4. Supplied by a dedicated 30-ampere circuit

Explanation

Receptacles rated 125 V, 15 or 20 A in dwelling-unit bathrooms require ground-fault circuit-interrupter protection. The requirement addresses the shock hazard created by water and grounded surfaces near the basin.

Question 5General Electrical Knowledge and Code Administration

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

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

Explanation

Receptacle outlets must be installed so that no point along the floor line of the wall space is more than 6 ft from an outlet. This generally spaces receptacles no more than 12 ft apart.

Question 6General Electrical Knowledge and Code Administration

A branch circuit wired with 14 AWG copper conductors may be protected by an overcurrent device with a maximum rating of which of the following?

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

Explanation

For 14 AWG copper, the small-conductor rule limits the branch-circuit overcurrent device to 15 A. That matches the 60 degrees C ampacity of the conductor.

Question 7General Electrical Knowledge and Code Administration

Receptacles are prohibited in a zone extending how far horizontally from the top of a bathtub rim or shower stall threshold?

  1. 6 ft
  2. 3 ft Correct answer.
  3. 8 ft
  4. 5 ft

Explanation

Receptacles may not be installed within a zone measured 3 ft horizontally and 8 ft vertically from the top of a bathtub rim or shower stall threshold. The zone keeps cord-connected appliances out of reach of a person in the tub or shower.

Question 8General Electrical Knowledge and Code Administration

In Michigan, a person who performs electrical work for another person for compensation generally must do which of the following?

  1. Hold a license issued under the state Electrical Administrative Act Correct answer.
  2. Obtain only a local building permit, with no state license
  3. Register with the electric utility that serves the premises
  4. Carry a manufacturer certification for the equipment installed

Explanation

Michigan regulates electricians through the Electrical Administrative Act, which requires licensure to perform electrical work for compensation. Permits, utility registration, and product certifications are separate matters and do not authorize the work.

Question 9General Electrical Knowledge and Code Administration

A box has a volume of 21.0 cubic inches. If each 12 AWG conductor is counted at 2.25 cubic inches, what is the maximum number of 12 AWG conductors the box may contain?

  1. 11 conductors
  2. 9 conductors Correct answer.
  3. 10 conductors
  4. 8 conductors

Explanation

Divide the box volume by the volume allowance per conductor: 21.0 divided by 2.25 equals 9.33. Only whole conductors count, so the box may contain no more than 9 of them.

Question 10General Electrical Knowledge and Code Administration

Where three or more conductors are installed in a raceway, the conductors may occupy no more than what percentage of the raceway's cross-sectional area?

  1. 40 percent Correct answer.
  2. 31 percent
  3. 60 percent
  4. 25 percent

Explanation

Raceway fill limits are 53 percent for one conductor, 31 percent for two conductors, and 40 percent for three or more conductors. The limits leave room for conductor installation and heat dissipation.

Question 11General Electrical Knowledge and Code Administration

Six current-carrying 10 AWG THHN conductors are installed in a single raceway. What ampacity adjustment factor applies?

  1. 50 percent
  2. 100 percent
  3. 70 percent
  4. 80 percent Correct answer.

Explanation

The adjustment table applies an 80 percent factor to circuits with four to six current-carrying conductors in a raceway or cable. The factor accounts for the reduced ability to dissipate heat when conductors are bundled.

Question 12General Electrical Knowledge and Code Administration

Conductors from 14 AWG through 1 AWG on circuits rated 100 amperes or less are generally required to be terminated using ampacities from which temperature column?

  1. 90 degrees C
  2. 75 degrees C
  3. The temperature marked on the conductor insulation
  4. 60 degrees C Correct answer.

Explanation

Terminations on circuits of 100 A or less using 14 AWG through 1 AWG conductors are limited to the 60 degrees C column unless the equipment is listed and identified for a higher temperature. The 90 degrees C column is used only for adjustment and correction calculations.

Question 13General Electrical Knowledge and Code Administration

The Code recommends that voltage drop on a feeder plus branch circuit, taken together, not exceed what percentage of the supply voltage?

  1. 8 percent
  2. 5 percent Correct answer.
  3. 3 percent
  4. 10 percent

Explanation

Informational notes recommend a maximum total voltage drop of 5 percent for feeder plus branch circuit, with no more than 3 percent on the branch circuit alone. These values are recommendations rather than mandatory rules.

Question 14General Electrical Knowledge and Code Administration

A 25-horsepower, 460-volt, three-phase motor has a full-load current of 34 amperes. Using a standard inverse-time circuit breaker for branch-circuit short-circuit and ground-fault protection, what is the maximum rating generally permitted?

  1. 102 amperes
  2. 68 amperes
  3. 85 amperes Correct answer.
  4. 119 amperes

Explanation

An inverse-time circuit breaker protecting a motor branch circuit may generally be set no higher than 250 percent of the motor full-load current. Here 2.50 times 34 amperes equals 85 amperes.

Question 15General Electrical Knowledge and Code Administration

Where a metal underground water pipe is used as a grounding electrode, the Code requires that the electrode be which of the following?

  1. Sized from the ampacity of the service-entrance conductors
  2. Bonded to the building steel with a 6 AWG conductor
  3. Supplemented by an additional grounding electrode Correct answer.
  4. Isolated from all interior metal piping

Explanation

A metal underground water pipe electrode must be supplemented by an additional electrode such as a ground rod or a concrete-encased electrode. The reason is that the pipe may later be replaced or repaired with a nonmetallic section.

Question 16General Electrical Knowledge and Code Administration

A 20-ampere branch circuit is wired with 12 AWG copper circuit conductors. What is the minimum size copper equipment grounding conductor?

  1. 8 AWG copper
  2. 10 AWG copper
  3. 12 AWG copper Correct answer.
  4. 14 AWG copper

Explanation

The equipment grounding conductor sizing table requires an equipment grounding conductor no smaller than 12 AWG copper for a 20-ampere circuit. For 15, 20, and 30 ampere circuits it generally matches the circuit conductor size.

Question 17General Electrical Knowledge and Code Administration

In a dwelling unit, the laundry branch circuit supplying the laundry receptacle outlets must have a minimum rating of which of the following?

  1. 20 amperes Correct answer.
  2. 15 amperes
  3. 40 amperes
  4. 30 amperes

Explanation

At least one 20-ampere branch circuit must be provided for the laundry receptacle outlets in a dwelling unit. That circuit may not supply outlets outside the laundry area.

Question 18General Electrical Knowledge and Code Administration

Which of the following dwelling-unit branch circuits requires arc-fault circuit-interrupter protection?

  1. A 120-volt, 20-ampere circuit supplying family room receptacles Correct answer.
  2. A 120-volt circuit supplying only an outdoor post light
  3. A 240-volt, 30-ampere circuit supplying a clothes dryer
  4. A 240-volt, 30-ampere circuit supplying a water heater

Explanation

Arc-fault protection is required for 120-volt, 15- and 20-ampere branch circuits supplying outlets in family rooms, living rooms, bedrooms, kitchens, and similar dwelling areas. Dedicated 240-volt appliance circuits and outdoor-only lighting are not on that list.

Question 19General Electrical Knowledge and Code Administration

A surface-mounted incandescent luminaire installed in a clothes closet must be kept at least what distance from the shelf?

  1. 18 inches
  2. 6 inches
  3. 24 inches
  4. 12 inches Correct answer.

Explanation

The closet luminaire table sets a 12-inch minimum clearance between a surface-mounted incandescent luminaire and the shelf. Other luminaire types, such as recessed or fluorescent fixtures, have different clearances.

Question 20General Electrical Knowledge and Code Administration

A junction box used in a wiring system must be which of the following?

  1. Listed for wet locations
  2. Fitted with a grounding bushing
  3. Accessible without removing building finish or structure Correct answer.
  4. Installed only in unfinished areas of a building

Explanation

Boxes must remain accessible so that the splices and connections inside them can be inspected and serviced. Accessibility means the box can be reached without cutting or removing any part of the building finish or structure.

Question 21General Electrical Knowledge and Code Administration

At service equipment, the main bonding jumper provides a connection between which of the following?

  1. The grounded service conductor and the equipment grounding bus Correct answer.
  2. The ungrounded conductors and the metal enclosure
  3. The grounding electrode and the metal water piping system
  4. The equipment grounding conductors and the grounding electrode conductor

Explanation

The main bonding jumper connects the grounded service conductor to the equipment grounding terminal bus at the service. This intentional connection creates the low-impedance return path needed for fault current to open the overcurrent device.

Question 22General Electrical Knowledge and Code Administration

A service is supplied by 2/0 AWG copper service-entrance conductors. What is the minimum size copper grounding electrode conductor where a metal underground water pipe is the electrode?

  1. 8 AWG copper
  2. 6 AWG copper
  3. 2 AWG copper
  4. 4 AWG copper Correct answer.

Explanation

For 2/0 AWG copper service conductors, the grounding electrode conductor table requires 4 AWG copper. The allowance that limits rod, pipe, and plate electrode conductors to 6 AWG does not apply to a water pipe electrode.

Question 23General Electrical Knowledge and Code Administration

Two motors are supplied by one branch circuit. One motor has a full-load current of 10 amperes and the other has a full-load current of 5 amperes. What is the minimum conductor ampacity for the branch circuit?

  1. 20.0 amperes
  2. 17.5 amperes Correct answer.
  3. 15.0 amperes
  4. 18.8 amperes

Explanation

A branch circuit supplying several motors is sized at 125 percent of the largest motor full-load current plus the sum of the other motor currents. Here 1.25 times 10 equals 12.5, and 12.5 plus 5 equals 17.5 amperes.

Question 24General Electrical Knowledge and Code Administration

For a photovoltaic array installed on a building, rapid shutdown must limit conductors within the array boundary to what value?

  1. 80 volts within 30 seconds Correct answer.
  2. 50 volts within 10 seconds
  3. 600 volts within 10 seconds
  4. 30 volts within 30 seconds

Explanation

Rapid shutdown must reduce conductors inside the array boundary to 80 volts or less within 30 seconds of initiation. Conductors outside the array boundary must be reduced to 30 volts within the same 30 seconds.

Question 25General Electrical Knowledge and Code Administration

A dwelling unit has a general lighting load of 8,000 volt-amperes. Using the standard demand factors of 100 percent for the first 3,000 volt-amperes and 35 percent for the remainder up to 120,000 volt-amperes, what is the calculated lighting demand?

  1. 8,000 volt-amperes
  2. 4,750 volt-amperes Correct answer.
  3. 4,000 volt-amperes
  4. 5,250 volt-amperes

Explanation

The first 3,000 volt-amperes is taken at 100 percent, giving 3,000 volt-amperes. The remaining 5,000 volt-amperes at 35 percent gives 1,750 volt-amperes, for a total of 4,750 volt-amperes.

Question 26General Electrical Knowledge and Code Administration

An energized 120/208-volt panelboard is installed in a room where there are no live parts on the opposite side of the aisle. What is the minimum depth of the working space required in front of the panelboard?

  1. 36 in Correct answer.
  2. 42 in
  3. 48 in
  4. 30 in

Explanation

NEC Table 110.26(A)(1) sets the minimum depth of working space in front of electrical equipment. Where the equipment operates at 150 volts to ground or less and no live parts are exposed on the opposite side of the aisle, the required depth is 3 ft (36 in). Greater depths apply only where live parts are exposed across the aisle.

Question 27General Electrical Knowledge and Code Administration

Between any two pull points in a run of electrical metallic tubing, the total accumulated bend shall not exceed which of the following?

  1. 360 degrees Correct answer.
  2. 180 degrees
  3. 270 degrees
  4. 540 degrees

Explanation

NEC 358.26 limits the total bend between pull points to the equivalent of four quarter bends, which is 360 degrees. Keeping within this limit allows conductors to be pulled without damage to insulation or excessive strain on the raceway.

Question 28General Electrical Knowledge and Code Administration

In Michigan, before regulated electrical work begins on a new commercial building, the installer must first do which of the following?

  1. Notify the serving utility and wait for its approval of the wiring method
  2. Submit a set of as-built drawings to the state electrical board
  3. Post a signed completion certificate at the job site
  4. Obtain an electrical permit from the enforcing agency Correct answer.

Explanation

Michigan's Electrical Administrative Act and the adopted electrical code require an electrical permit from the enforcing agency before regulated electrical work is started, so the installation can be inspected in stages. Working without the required permit can result in citations, additional fees, and required removal or re-inspection of covered work.

Question 29General Electrical Knowledge and Code Administration

In a dwelling unit living room, what is the maximum distance measured along the floor line from any point on a wall space to the nearest receptacle outlet?

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

Explanation

NEC 210.52(A) requires receptacle outlets in dwelling unit rooms so that no point along the floor line of any wall space is more than 6 ft from an outlet. This spacing limits reliance on extension cords and cords run across walkways.

Question 30General Electrical Knowledge and Code Administration

A 60-ampere, three-phase branch circuit is protected by a 60-ampere circuit breaker. What is the minimum size copper equipment grounding conductor permitted for this circuit?

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

Explanation

NEC Table 250.122 sizes the equipment grounding conductor according to the rating of the overcurrent device protecting the circuit. For a 60-ampere device, the minimum copper equipment grounding conductor is 10 AWG.

Question 31General Electrical Knowledge and Code Administration

A single driven ground rod serves as the grounding electrode for a service. When measured, its resistance to earth is 40 ohms. What does the Code require in this situation?

  1. No action is needed because any resistance below 50 ohms is acceptable.
  2. The rod must be replaced with a concrete-encased electrode.
  3. The grounding electrode conductor must be increased one trade size.
  4. A second electrode of a listed type must be installed and bonded to the first. Correct answer.

Explanation

NEC 250.53(A)(2) requires a single rod, pipe, or plate electrode to be supplemented by an additional electrode unless its resistance to earth is 25 ohms or less. The supplemental electrode must be bonded to the first electrode, and where a second rod is used the rods must be spaced at least 6 ft apart.

Question 32General Electrical Knowledge and Code Administration

Which statement correctly describes identification of the grounded conductor when a 4 AWG conductor is used as a neutral?

  1. It must be marked with three continuous white stripes along its length.
  2. It may be re-identified with green marking at its terminations.
  3. It must be factory-jacketed white or gray over its entire length.
  4. It may be re-identified with white or gray marking at its terminations. Correct answer.

Explanation

NEC 200.6 requires grounded conductors 6 AWG and smaller to be white or gray for their entire length. Conductors 4 AWG and larger may instead be re-identified at terminations using white or gray tape, paint, or similar marking.

Question 33General Electrical Knowledge and Code Administration

Where must the disconnecting means for a 480-volt motor be located relative to the motor?

  1. Within sight of the motor and within 50 ft of it Correct answer.
  2. Within sight of the motor and within 25 ft of it
  3. In the same room as the controller and equipped with a lock
  4. Anywhere on the same floor of the building as the motor

Explanation

NEC 430.102(B) requires a motor disconnecting means that is within sight of the motor and not more than 50 ft from it. This allows a worker to see the disconnect and confirm the motor is de-energized while servicing it.

Question 34General Electrical Knowledge and Code Administration

A 15-ampere, 125-volt receptacle outlet is installed outdoors on the wall of a dwelling unit to serve a patio. Which of the following is required for this outlet?

  1. It must be GFCI protected. Correct answer.
  2. It must be supplied by a 30-ampere circuit.
  3. It must be bonded to a ground rod at the outlet.
  4. It must be on a dedicated 20-ampere circuit.

Explanation

NEC 210.8(A) requires ground-fault circuit-interrupter protection for 125-volt, 15- and 20-ampere receptacle outlets installed outdoors at dwelling units. The protection is required because of the increased shock hazard from moisture and contact with the earth.

Question 35General Electrical Knowledge and Code Administration

Straight runs of electrical metallic tubing must be securely fastened in place at intervals not exceeding which distance?

  1. Every 6 ft
  2. Every 10 ft Correct answer.
  3. Every 12 ft
  4. Every 15 ft

Explanation

NEC 358.30 requires EMT to be fastened within 3 ft of each box, cabinet, fitting, or termination and at intervals not exceeding 10 ft along the run. Proper support keeps the raceway from sagging and prevents strain at terminations.

Question 36General Electrical Knowledge and Code Administration

What is the minimum permitted clearance of overhead service-drop conductors above a residential driveway?

  1. 10 ft
  2. 18 ft
  3. 12 ft Correct answer.
  4. 15 ft

Explanation

NEC 230.24 sets minimum vertical clearances for service-drop conductors above the areas they cross. Above a residential driveway or a parking area the required clearance is 12 ft, measured at the lowest point of the sag.

Question 37General Electrical Knowledge and Code Administration

A balanced three-phase load of 20 amperes is supplied at 480 volts with a power factor of 0.80. What is the approximate real power drawn by the load?

  1. 13.3 kW Correct answer.
  2. 9.6 kW
  3. 28.8 kW
  4. 16.6 kW

Explanation

Real power for a balanced three-phase load is calculated as P = 1.732 x V x I x power factor. Substituting gives 1.732 x 480 V x 20 A x 0.80, which equals approximately 13.3 kW.

Question 38General Electrical Knowledge and Code Administration

A dwelling unit contains one electric range rated 12 kW. Using NEC Table 220.55, what demand load is used for this range in the service calculation?

  1. 6 kW
  2. 9.6 kW
  3. 8 kW Correct answer.
  4. 12 kW

Explanation

NEC Table 220.55 permits household electric ranges to be calculated at less than their nameplate rating. For a single range rated 12 kW or less, the table permits a demand load of 8 kW, which is 80 percent of the maximum range rating.

Question 39General Electrical Knowledge and Code Administration

A branch circuit supplies a 40-ampere continuous load and a 20-ampere noncontinuous load. What is the minimum rating of the overcurrent device protecting the circuit, assuming the conductors are properly sized?

  1. 80 A
  2. 70 A Correct answer.
  3. 75 A
  4. 60 A

Explanation

NEC 210.20(A) requires the overcurrent device to be rated not less than 125 percent of the continuous load plus 100 percent of the noncontinuous load. Here 1.25 x 40 A plus 20 A equals 70 A, which is itself a standard device rating.

Question 40General Electrical Knowledge and Code Administration

A 120-volt, 20-ampere load is located 100 ft from a panelboard and is wired with 12 AWG copper conductors having a resistance of 1.93 ohms per 1000 ft. What is the approximate voltage drop on the circuit?

  1. 11.6 V
  2. 7.7 V Correct answer.
  3. 15.4 V
  4. 3.9 V

Explanation

Voltage drop for a two-wire circuit is computed as 2 x L x R x I, where L is the one-way length in thousands of feet. That gives 2 x 0.100 kft x 1.93 ohms/kft x 20 A, which equals approximately 7.7 volts.

Question 41Services, Feeders, and Branch Circuits

Overhead service-drop conductors cross a residential driveway that carries only passenger vehicles. What is the minimum vertical clearance required above the driveway surface?

  1. 10 ft
  2. 15 ft
  3. 18 ft
  4. 12 ft Correct answer.

Explanation

NEC 230.24(B)(1) sets the minimum clearance above residential driveways and commercial areas not subject to truck traffic at 12 ft. The 10 ft value applies only to sidewalks and areas accessible to pedestrians alone, while 18 ft applies to public streets and areas where truck traffic is expected.

Question 42Services, Feeders, and Branch Circuits

What is the minimum depth of working space in front of a 480-volt panelboard where the energized parts are exposed on one side and there are no grounded or energized parts on the opposite side?

  1. 2 1/2 ft
  2. 3 1/2 ft
  3. 2 ft
  4. 3 ft Correct answer.

Explanation

Table 110.26(A)(1) bases the required depth on the voltage and on the conditions found across the working space. Condition 1, where exposed live parts exist on one side only and no grounded or live parts are on the other, requires 3 ft for equipment rated 600 volts or less.

Question 43Services, Feeders, and Branch Circuits

Service-drop conductors pass over the roof of a building with a slope of 3/12. What minimum clearance must be maintained above the roof surface?

  1. 3 ft
  2. 4 ft
  3. 8 ft Correct answer.
  4. 6 ft

Explanation

Section 230.24(A) requires service-drop conductors to maintain 8 ft of clearance above the roof surface as a general rule. Reduced clearances are allowed only under the specific exceptions, such as roofs steeper than 4/12, so a 3/12 roof keeps the full 8 ft requirement.

Question 44Services, Feeders, and Branch Circuits

In a dwelling unit, what does the general receptacle spacing rule require along a bedroom wall that is broken by a doorway?

  1. A receptacle outlet must be installed every 12 ft of wall space
  2. A receptacle outlet must be installed within 4 ft of each doorway
  3. No point along the floor line may be more than 12 ft from a receptacle outlet
  4. No point along the floor line may be more than 6 ft from a receptacle outlet Correct answer.

Explanation

Section 210.52(A)(1) requires receptacle outlets so that no point along the floor line in any wall space is more than 6 ft, measured horizontally, from an outlet in that space. The wall space itself is measured around corners and includes the 2 ft of wall beside a doorway.

Question 45Services, Feeders, and Branch Circuits

How many small-appliance branch circuits must be provided for the kitchen, pantry, and dining area receptacles of a dwelling unit?

  1. One 20-ampere circuit
  2. One 15-ampere circuit
  3. Two or more 20-ampere circuits Correct answer.
  4. Two or more 15-ampere circuits

Explanation

Section 210.11(C)(1) requires at least two 20-ampere small-appliance branch circuits to supply the receptacle outlets in the kitchen, pantry, breakfast room, and dining room. These circuits may also serve the receptacles in those same areas but must remain 20-ampere circuits.

Question 46Services, Feeders, and Branch Circuits

Which arrangement satisfies the branch-circuit requirement for bathroom receptacle outlets in a dwelling unit?

  1. A 20-ampere circuit supplying only bathroom receptacle outlets Correct answer.
  2. A 15-ampere circuit supplying both the bathroom receptacles and the hallway receptacles
  3. A 15-ampere circuit dedicated to the bathroom lighting outlets
  4. A 20-ampere circuit shared between the bathroom receptacles and the garage receptacles

Explanation

Section 210.11(C)(3) requires at least one 20-ampere branch circuit to supply the bathroom receptacle outlets, and that circuit is not permitted to supply outlets outside the bathroom. A 15-ampere circuit or one that also feeds the garage or hallway would not comply.

Question 47Services, Feeders, and Branch Circuits

Which branch circuit is permitted to serve the laundry receptacle outlets of a dwelling unit?

  1. A 15-ampere circuit protected by a GFCI circuit breaker
  2. A 15-ampere circuit shared with the dining room receptacles
  3. A 20-ampere circuit supplying only laundry receptacle outlets Correct answer.
  4. A 20-ampere circuit that also supplies the garage receptacles

Explanation

Section 210.11(C)(2) requires at least one 20-ampere branch circuit for the laundry receptacle outlet, and that circuit is limited to supplying laundry outlets. Sharing it with dining room or garage receptacles, or reducing it to 15 amperes, does not meet the requirement.

Question 48Services, Feeders, and Branch Circuits

What is the minimum size copper conductor permitted for a 15-ampere branch circuit supplying general-use receptacles?

  1. 10 AWG copper
  2. 12 AWG copper
  3. 16 AWG copper
  4. 14 AWG copper Correct answer.

Explanation

Table 310.16 and 240.4(D) permit 14 AWG copper to be protected at 15 amperes, making it the smallest conductor allowed for a 15-ampere branch circuit. Conductors smaller than 14 AWG are not permitted for this use regardless of the overcurrent device rating.

Question 49Services, Feeders, and Branch Circuits

What is the minimum rating permitted for the service disconnecting means of a one-family dwelling?

  1. 100 amperes Correct answer.
  2. 60 amperes
  3. 200 amperes
  4. 125 amperes

Explanation

Section 230.79(C) requires the service disconnecting means for a one-family dwelling to have a rating of not less than 100 amperes. Higher ratings are common but are selected from the calculated load, not mandated as a minimum.

Question 50Services, Feeders, and Branch Circuits

Using the standard method, how is the general lighting load of a dwelling unit treated by Table 220.42?

  1. First 3000 VA at 100 percent, with the remainder at 35 percent Correct answer.
  2. First 10,000 VA at 100 percent, with the remainder at 40 percent
  3. First 3000 VA at 100 percent, with the remainder at 40 percent
  4. The entire general lighting load is taken at 100 percent

Explanation

Table 220.42 applies a 100 percent demand factor to the first 3000 VA of dwelling general lighting load and a 35 percent factor to the remainder. Applying 100 percent to the entire load would overstate the demand used for service and feeder sizing.