National Electrical Code (NEC) Exam (Journeyman/Master Electrician) — Questions and Answers

Question 1: Per NEC 240.86, where a circuit breaker is used on a circuit with available fault current higher than its marked interrupting rating, what method may permit a series combination rating?

Using a larger enclosure
Adding a surge protector
Doubling the conductor size
Selected under engineering supervision or marked as a tested series-rated combination (Correct answer)

Correct answer: Selected under engineering supervision or marked as a tested series-rated combination

NEC 240.86 allows series ratings either selected under engineering supervision or as tested/marked listed combinations.

Question 2: In a 3/4 EMT trade size, how many 10 AWG RHH conductors may be installed?

6 conductors (Correct answer)
3 conductors
5 conductors
8 conductors

Correct answer: 6 conductors

Total 6 10 AWG RHH conductors can be installed in trade size ¾ EMT.

Question 3: A main bonding jumper is being installed in a service panel. Its size is determined based on which of the following?

The available fault current at the service
The size of the ungrounded service-entrance conductors (Correct answer)
The rating of the main overcurrent protection device
The size of the grounding electrode conductor

Correct answer: The size of the ungrounded service-entrance conductors

According to NEC 250.28(D) and Table 250.102(C)(1), the main bonding jumper shall be sized based on the size of the ungrounded service-entrance conductors. This ensures the jumper can safely carry any fault current it might be subjected to.

Question 4: What is required at the point of pool equipment per NEC Article 680 for safety?

Higher voltage supply
No special bonding
Plastic conduit only
Equipotential bonding grid (Correct answer)

Correct answer: Equipotential bonding grid

NEC Article 680 requires an equipotential bonding grid around pools to eliminate voltage gradients.

Question 5: Unless specifically permitted otherwise, what is the maximum overcurrent protection allowed for a 12 AWG copper conductor according to NEC 240.4(D)?

15A
25A
20A (Correct answer)
30A

Correct answer: 20A

NEC 240.4(D) provides specific overcurrent protection limitations for small conductors. For 12 AWG copper conductors, the maximum standard overcurrent protective device rating is 20 amperes, regardless of the conductor's higher ampacity rating listed in Table 310.16.

Question 6: Per Table 430.52, what is the maximum rating of an inverse-time circuit breaker used as branch-circuit short-circuit and ground-fault protection for a standard squirrel-cage (non-Design B energy-efficient) motor?

125% of FLC
250% of FLC (Correct answer)
175% of FLC
800% of FLC

Correct answer: 250% of FLC

Table 430.52 sets 250% of FLC for inverse-time breakers on most AC squirrel-cage motors. Dual-element time-delay fuses are 175%, non-time-delay fuses are 300%, and instantaneous-trip breakers are 800% (1100% for Design B energy-efficient motors).

Question 7: Which article governs electrical installations in recreational vehicle parks?

Article 551 (Correct answer)
Article 700
Article 553
Article 280

Correct answer: Article 551

NEC Article 551 is dedicated to the electrical installations within recreational vehicle (RV) parks and campgrounds. It outlines the specific requirements for RV sites, feeders, and service equipment, ensuring safe and reliable power connections for temporary or seasonal RV occupants. This article addresses the unique challenges of providing electrical service to transient vehicles.

Question 8: A commercial building has 50,000 sq ft of office space. Using NEC Table 220.12, what is the minimum general lighting load in VA?

250,000 VA
175,000 VA (Correct answer)
150,000 VA
100,000 VA

Correct answer: 175,000 VA

NEC Table 220.12 assigns 3.5 VA/sq ft for office spaces; 50,000 × 3.5 = 175,000 VA.

Question 9: Under NEC 110.26(F), dedicated equipment space above a panelboard must extend from the top of the equipment to the structural ceiling or to a maximum height of:

25 ft above the equipment (Correct answer)
The top of the equipment with no extension required
18 inches above the equipment
6 ft above the floor

Correct answer: 25 ft above the equipment

NEC 110.26(F)(1) requires the dedicated equipment space to extend from the top of the electrical equipment up to the structural ceiling or 6 m (25 ft) above the equipment, whichever is lower.

Question 10: What is the ampacity correction factor that must be applied when four current-carrying conductors are bundled together in a cable tray?

0.60 (60%)
0.90 (90%)
0.70 (70%)
0.80 (80%) (Correct answer)

Correct answer: 0.80 (80%)

NEC Table 310.15(C)(1) requires an 80% ampacity correction factor when 4 to 6 current-carrying conductors are bundled or stacked.

Question 11: Which of the following locations in a dwelling unit requires GFCI protection for all 125-volt through 250-volt receptacles supplied by single-phase branch circuits rated 150 volts or less to ground?

Hallways
Closets
Basements (finished or unfinished) (Correct answer)
Bedrooms

Correct answer: Basements (finished or unfinished)

NEC Section 210.8(A)(5) was revised to require GFCI protection for all 125-volt through 250-volt receptacles in basements, regardless of whether they are finished or unfinished. This is a broader requirement than those for hallways, bedrooms, or closets, which primarily fall under AFCI protection rules.

Question 12: Per NEC 210.11(C)(3), at least one 20-ampere branch circuit must supply bathroom receptacle outlets. Which statement about that circuit is correct?

It may also supply kitchen countertop receptacles
It must be rated 30 A when serving more than one bathroom
It must be a multiwire branch circuit
It may supply other bathroom equipment if it serves only a single bathroom (Correct answer)

Correct answer: It may supply other bathroom equipment if it serves only a single bathroom

A bathroom receptacle circuit may serve only bathroom receptacles, unless it supplies a single bathroom, in which case it may also feed other equipment in that bathroom per 210.23(A) limits.

Question 13: Listed flexible metal conduit (FMC) with listed fittings can serve as the equipment grounding conductor only if the total length in the ground return path does not exceed what?

3 feet
10 feet
4.5 feet
6 feet (Correct answer)

Correct answer: 6 feet

NEC 250.118 allows FMC as an EGC only when the circuit is protected at 20 A or less and the combined length is no more than 6 ft.

Question 14: Per NEC 240.21, overcurrent protection is generally required at what point of a conductor?

At every junction box
The point where the conductor receives its supply (Correct answer)
The midpoint of the run
The load end only

Correct answer: The point where the conductor receives its supply

NEC 240.21 requires overcurrent protection at the point where the conductor receives its supply, except for specified tap rules.

Question 15: What does Article 555 of the NEC cover?

Marinas and boatyards (Correct answer)
Mobile homes
Healthcare areas
Classroom lighting

Correct answer: Marinas and boatyards

Article 555 of the NEC covers the specific requirements for electrical installations in marinas, boatyards, and docking facilities. These locations present unique hazards due to the proximity of water, potential for corrosion, and the interaction of shore power with vessels. The article provides specialized safety provisions to mitigate risks such as electric shock and fire in these environments.

Question 16: Under NEC 517.13(B), branch circuits serving patient care spaces must include what in addition to the metal raceway to provide redundant grounding?

A grounding electrode conductor
A bonding jumper to the panelboard
A separate isolated ground conductor
An insulated copper equipment grounding conductor (Correct answer)

Correct answer: An insulated copper equipment grounding conductor

NEC 517.13(B) requires an insulated copper equipment grounding conductor in addition to the metal raceway, providing two independent grounding paths in patient care spaces for maximum safety.

Question 17: Per NEC 210.8(A), which 125-volt through 250-volt receptacles in a dwelling unit require GFCI protection?

Only those serving dedicated refrigerators in kitchens
Those in garages and accessory buildings with floors at or below grade (Correct answer)
Only those in bedrooms
Only receptacles above 6 ft

Correct answer: Those in garages and accessory buildings with floors at or below grade

Garages and accessory buildings are among the dwelling locations listed in 210.8(A) that require GFCI protection.

Question 18: Which device is commonly used for branch circuit overcurrent protection?

Contactor
Circuit breaker (Correct answer)
Transfer switch
Surge protector

Correct answer: Circuit breaker

A circuit breaker is the device most commonly used for branch circuit overcurrent protection in modern electrical installations. Unlike a fuse, which is a single-use device, a circuit breaker can be manually reset after it trips due to an overcurrent condition. This makes it a convenient and reusable safety device that protects wiring and equipment from damage.

Question 19: When sizing conductors and short-circuit protection for a general-purpose motor, where does the full-load current value come from?

The motor nameplate
A clamp-meter reading at startup
NEC Tables 430.247 through 430.250 (Correct answer)
The manufacturer's catalog

Correct answer: NEC Tables 430.247 through 430.250

NEC 430.6(A)(1) requires the table FLC values (Tables 430.247–430.250) for conductor ampacity and branch-circuit short-circuit and ground-fault protection. Separate overload protection is sized from the nameplate current.

Question 20: For a feeder serving six household dishwashers in a multifamily building, per NEC 220.53, what demand factor applies to four or more fixed appliances on the same feeder?

50%
75% (Correct answer)
65%
100%

Correct answer: 75%

NEC 220.53 allows a 75% demand factor when four or more fixed appliances (other than ranges, dryers, A/C, and heating) are on the same feeder or service.

Question 21: Under the 25-foot tap rule of NEC 240.21(B)(2), the tap conductors must have an ampacity at least what fraction of the feeder overcurrent device rating?

Equal to
One-tenth
One-half
One-third (Correct answer)

Correct answer: One-third

The 25-ft tap rule requires tap conductors to have ampacity not less than one-third of the feeder OCPD rating.

Question 22: What is 'inductive reactance' and how does it relate to frequency?

Resistance in a coil; it is independent of frequency
Opposition to AC current in an inductor; it increases as frequency increases (Correct answer)
Opposition to current in a capacitor; it decreases as frequency increases
Opposition to DC current; it decreases as frequency increases

Correct answer: Opposition to AC current in an inductor; it increases as frequency increases

Inductive reactance (XL = 2πfL) is the opposition to AC current in an inductive element, and it increases proportionally with increasing frequency.

Question 23: Under NEC 250.50, when multiple grounding electrodes are present at a structure, what must be done?

They must be connected in series to increase resistance
Each electrode requires its own separate grounding electrode conductor
They must all be bonded together to form a grounding electrode system (Correct answer)
Only one electrode may be used; the others must be removed

Correct answer: They must all be bonded together to form a grounding electrode system

NEC 250.50 requires all grounding electrodes present at a structure to be bonded together into a single grounding electrode system.

Question 24: Given: The local utility company provides a 120/240 volt, single-phase electrical system to a one-family dwelling unit with a demand load of 200 amperes. What is the MINIMUM size of aluminum THW conductors required for this residence's service-entrance conductors?

1/0 AWG
2/0 AWG
4/0 AWG (Correct answer)
3/0 AWG

Correct answer: 4/0 AWG

Section 310.15(B)(7)(1) permits one-family dwelling 120/240 volt, single-phase, service-entrance conductors to be sized at an ampacity of not less than 83% of the service rating. Therefore, 200 amperes x 83% = 166 amperes Table 310.15(B)(16) indicates size 4/0 AWG THW aluminum conductors with an allowable ampacity of 180 amperes should be selected for this dwelling.

Question 25: What minimum rating is required for the branch circuit supplying dwelling unit bathroom receptacle outlets?

20 amperes (Correct answer)
30 amperes
15 amperes
25 amperes

Correct answer: 20 amperes

NEC 210.11(C)(3) requires at least one 20-ampere branch circuit to supply bathroom receptacle outlets.

Question 26: What is the demand factor allowed for the first 3,000 VA of general lighting load in a dwelling?

100% (Correct answer)
75%
35%
40%

Correct answer: 100%

NEC Table 220.42 applies 100% to the first 3,000 VA of dwelling general lighting load.

Question 27: What is the minimum size copper grounding electrode conductor required for a 200-ampere service with a single ground rod electrode per NEC Article 250?

6 AWG copper (Correct answer)
4 AWG copper
2 AWG copper
8 AWG copper

Correct answer: 6 AWG copper

NEC 250.66 limits the grounding electrode conductor to a single rod, pipe, or plate electrode to 6 AWG copper regardless of service size.

Question 28: Under NEC 210.52(A)(1), receptacles in dwelling habitable rooms must be installed so that no point along the floor line of any wall space is more than how far from a receptacle?

4 ft
6 ft (Correct answer)
8 ft
12 ft

Correct answer: 6 ft

No point along the floor line may be more than 6 ft from a receptacle, which effectively gives a maximum spacing of 12 ft.

Question 29: A branch circuit supplies a 16-ampere continuous load with no noncontinuous load. Per NEC 210.20(A), what is the minimum overcurrent device rating?

16 A
25 A
30 A
20 A (Correct answer)

Correct answer: 20 A

16 A × 125% = 20 A, so a 20-ampere device is the minimum.

Question 30: What is the minimum number of receptacles required at each patient bed location in a critical care (Category 1) space?

10
6
8
14 (Correct answer)

Correct answer: 14

NEC 517.19(B)(1) requires at least 14 receptacles at each critical care patient bed location.

Question 31: Countertop receptacles in a dwelling kitchen must be installed so no point along the counter wall is more than what distance from a receptacle?

36 inches
18 inches
24 inches (Correct answer)
12 inches

Correct answer: 24 inches

NEC 210.52(C)(1) requires no point more than 24 inches from a countertop receptacle.

Question 32: Which of the following locations is a required point of attachment for bonding an interior metal water piping system in a building?

To the equipment grounding conductor of the largest branch circuit
Within 10 feet of where the water pipe enters the building
To the nearest metal structural frame of the building
The service equipment enclosure (Correct answer)

Correct answer: The service equipment enclosure

NEC Section 250.104(A)(1) requires the metal water piping system to be bonded to the service equipment enclosure, the grounded service conductor, the grounding electrode conductor, or one of the grounding electrodes used. The service equipment enclosure is one of the specifically listed and most common points of attachment.

Question 33: For a service drop of 300 volts to ground or less, what is the minimum vertical clearance above residential property and driveways that are not subject to truck traffic?

10 ft
18 ft
15 ft
12 ft (Correct answer)

Correct answer: 12 ft

NEC 230.24(B)(2) requires 12 ft over residential property and driveways, and over commercial areas not subject to truck traffic, where the voltage does not exceed 300 V to ground. 10 ft applies to pedestrian-only areas at 150 V to ground or less. 18 ft applies over public streets and areas with truck traffic.

Question 34: In dwelling unit habitable rooms, receptacles must be placed so that no point along the floor line of a wall is more than how far from a receptacle?

6 feet (Correct answer)
12 feet
8 feet
4 feet

Correct answer: 6 feet

NEC 210.52(A)(1) sets the 6-foot rule, resulting in receptacles about every 12 feet.

Question 35: Which conductor is NOT counted as a current-carrying conductor for ampacity adjustment in a normally balanced circuit?

A conductor feeding a single-phase load
The ungrounded phase conductor
An equipment grounding conductor that carries fault current
The neutral of a balanced 3-wire system (Correct answer)

Correct answer: The neutral of a balanced 3-wire system

A neutral carrying only the unbalanced current of a balanced multiwire circuit is not counted as current-carrying.

Question 36: The small-appliance branch circuits in a dwelling kitchen are NOT permitted to supply which of the following?

Refrigerator
Lighting outlets (Correct answer)
Dining room receptacles
Countertop receptacles

Correct answer: Lighting outlets

NEC 210.52(B)(2) prohibits small-appliance circuits from supplying lighting outlets.

Question 37: Which of the following is NOT an acceptable grounding electrode per NEC 250.52?

A metal in-ground support structure
A concrete-encased electrode
A plastic water pipe (Correct answer)
A ground ring

Correct answer: A plastic water pipe

Plastic water pipe is not conductive and cannot serve as a grounding electrode; NEC 250.52 lists only metal or conductive electrodes.

Question 38: What is the basic unit of electric current?

Watt
Ohm
Volt
Ampere (Correct answer)

Correct answer: Ampere

The ampere (A), often shortened to 'amp,' is the basic SI unit of electric current. It measures the rate of flow of electric charge past a point in an electrical circuit. Understanding the ampere is fundamental to electrical engineering and is a key component in calculations involving power and resistance.

Question 39: What is the maximum percentage of conduit cross-sectional area that can be filled by three or more conductors in a conduit longer than 24 inches?

31%
53%
40% (Correct answer)
60%

Correct answer: 40%

Chapter 9, Table 1 limits fill to 40% for more than two conductors.

Question 40: The voltmeter at one end of the feeder reads 240 volts. What is the volt-minimum meter's reading voltage at the outlet of lighting loads?

228 volts
240 volts
232.8 volts (Correct answer)
235 volts

Correct answer: 232.8 volts

The maximum voltage drop in feeder is 3 % the voltmeter reading = 240 – 0.03 * 240 = 240 – 7.2 = 232.8 volts

Question 41: According to NEC Article 408, every circuit in a panelboard must be legibly identified as to its specific purpose. Which of the following directory entries would be considered NON-COMPLIANT for a circuit breaker position that has no breaker or wiring installed?

Master Bedroom Lights
Garage Door Opener
Kitchen Counter Receptacles
Future Use (Correct answer)

Correct answer: Future Use

NEC 408.4(A) requires identification for each circuit to be clear and specific. While positions with unused overcurrent devices should be marked 'Spare,' the term 'Future Use' is not permitted because it is not specific. The intent is to clearly identify the purpose of every active or potentially active circuit position.

Question 42: According to NEC Article 511, commercial garages used for repair and storage of vehicles require special electrical treatment up to what height above the floor?

18 inches (Correct answer)
12 inches
24 inches
6 inches

Correct answer: 18 inches

NEC 511.3 designates the area within 18 inches of the floor as Class I, Division 2 in commercial garages where flammable fuels are used.

Question 43: Under NEC 210.12, AFCI protection is required for 120-volt, 15- and 20-ampere branch circuits supplying outlets in which dwelling location?

Bedrooms (Correct answer)
Unfinished crawl spaces only
Service equipment rooms only
Outdoor receptacles only

Correct answer: Bedrooms

Bedrooms, along with most other habitable areas, kitchens, and laundry areas, require AFCI protection under 210.12.

Question 44: What is the minimum size equipment grounding conductor (copper) for a circuit protected by a 100A overcurrent device per Table 250.122?

8 AWG (Correct answer)
10 AWG
6 AWG
4 AWG

Correct answer: 8 AWG

NEC Table 250.122 specifies 8 AWG copper for a 100A overcurrent device.

Question 45: What is the standard ampere rating immediately above 100 A in the NEC 240.6(A) list of standard fuse and circuit breaker ratings?

125 amperes
115 amperes
150 amperes
110 amperes (Correct answer)

Correct answer: 110 amperes

NEC 240.6(A) lists 110 A as the standard rating directly above 100 A.

Question 46: What does the NEC mean by the term 'authority having jurisdiction' (AHJ)?

The National Fire Protection Association (NFPA) board of directors
An organization, office, or individual responsible for enforcing the requirements of a code, or their designated representative (Correct answer)
The electrical contractor licensed in the state where work is performed
The utility company providing power to the installation

Correct answer: An organization, office, or individual responsible for enforcing the requirements of a code, or their designated representative

The AHJ is defined in Article 100 as the organization, office, or individual responsible for enforcing the requirements of a code, or a designated representative.

Question 47: According to NEC 2023, what is the minimum size copper equipment grounding conductor (EGC) required for a 60-ampere branch circuit protected by an overcurrent device?

6 AWG
8 AWG
10 AWG (Correct answer)
12 AWG

Correct answer: 10 AWG

NEC Table 250.122 specifies the minimum size equipment grounding conductor for grounding raceways and equipment. For a circuit with a 60-ampere overcurrent device, the table requires a minimum of a 10 AWG copper conductor.

Question 48: When using a portable ladder near energized electrical equipment, which material is safest?

Fiberglass (Correct answer)
Aluminum
Copper-reinforced
Steel

Correct answer: Fiberglass

Fiberglass ladders are non-conductive, making them safest near energized equipment.

Question 49: Under NEC 250.104, what must be bonded in a building that has a metal gas piping system?

The metal gas piping must be bonded to the equipment grounding conductor (Correct answer)
Gas piping requires no bonding if it enters through plastic fittings
Gas piping must be bonded to the water pipe only
Gas piping must be bonded to the grounding electrode directly

Correct answer: The metal gas piping must be bonded to the equipment grounding conductor

NEC 250.104(B) requires metal gas piping to be bonded to the equipment grounding conductor of the circuit that may energize the piping.

Question 50: What is the minimum height clearance for overhead service-drop conductors above a residential driveway?

15 feet
18 feet
10 feet
12 feet (Correct answer)

Correct answer: 12 feet

Service-drop conductors must maintain at least 12 feet of clearance over residential driveways.

Question 51: A single rod electrode must be supplemented by an additional electrode unless its resistance to earth is at most what value?

50 ohms
10 ohms
5 ohms
25 ohms (Correct answer)

Correct answer: 25 ohms

NEC 250.53(A)(2) exempts the supplemental electrode only when a single rod has 25 ohms or less resistance.

Question 52: Equipment with cords and plugs cannot be rated at more than ______ of the branch circuit rating if it is not fixed in place.

80% (Correct answer)
125%
100%
75%

Correct answer: 80%

NEC 210.23(A)(1) states that the total rating of cord-and-plug-connected utilization equipment not fastened in place shall not exceed 80% of the branch-circuit ampere rating. This rule provides a safety margin, preventing continuous overloading of the circuit, which could lead to overheating of conductors and overcurrent devices. It accounts for the intermittent nature of such loads and the potential for multiple devices to be plugged in.

Question 53: Per NEC 250.122, how is the minimum size of an equipment grounding conductor (EGC) determined for a branch circuit?

Based on the load ampacity of the circuit
Based on the rating of the overcurrent protective device (Correct answer)
Based on the wire gauge of the ungrounded conductors
Based on the total length of the circuit

Correct answer: Based on the rating of the overcurrent protective device

NEC 250.122 Table sizes the EGC according to the rating of the circuit's overcurrent protective device.

Question 54: A 5 kW electric water heater is installed in a closet. The circuit breaker for the water heater is in a panelboard located down the hall and is not within sight of the appliance. To comply with NEC Article 422, what is required for the circuit breaker to serve as the disconnecting means?

It must be a GFCI type breaker.
It must be capable of being locked in the open position. (Correct answer)
It must be labeled 'Water Heater Disconnect.'
It must be rated at least 150% of the appliance load.

Correct answer: It must be capable of being locked in the open position.

NEC 422.31(B) states that for a permanently connected appliance rated over 300 VA, the branch-circuit overcurrent device (breaker) can be the disconnecting means. If the breaker is not within sight of the appliance, it must be capable of being locked in the open position to ensure safety during service.

Question 55: NEC Section 110.12 requires electrical equipment to be installed in a:

Dedicated electrical room only
Manner approved by the local fire marshal
Neat and workmanlike manner (Correct answer)
Metallic enclosure whenever possible

Correct answer: Neat and workmanlike manner

Section 110.12 mandates that electrical equipment be installed in a neat and workmanlike manner, ensuring reliable, safe operation.

Question 56: According to NEC 250.64(C), a grounding electrode conductor may be spliced only by which methods?

Twist-on wire connectors (wire nuts)
Any UL-listed connector
Irreversible compression connectors or exothermic welding (Correct answer)
Listed split-bolt connectors only

Correct answer: Irreversible compression connectors or exothermic welding

NEC 250.64(C) limits GEC splices to irreversible (compression) connectors or exothermic welding to ensure a reliable connection.

Question 57: In electrical theory, if voltage remains constant and resistance doubles, what happens to current?

Current increases by the square root of 2
Current remains the same
Current doubles
Current is halved (Correct answer)

Correct answer: Current is halved

By Ohm's Law (I = V/R), if voltage is constant and resistance doubles, the current is halved.

Question 58: Under NEC 230.54, where must a service head be located relative to the point of attachment of the service-drop conductors?

Anywhere within 10 ft of the point of attachment
At the same height as the meter base
Above the point of attachment, or within 24 in. of it where that is impracticable (Correct answer)
Below the point of attachment

Correct answer: Above the point of attachment, or within 24 in. of it where that is impracticable

NEC 230.54(C) requires service heads to be above the point of attachment so water does not run into the raceway. Where that is impracticable, the exception allows the head within 24 in. of the point of attachment.

Question 59: An electrician is installing a new branch circuit in a dwelling unit laundry area. The circuit will supply a 120-volt receptacle for a washing machine. According to the 2023 NEC, what type of protection is required for this receptacle?

Overcurrent protection only
AFCI protection only
GFCI protection only
Both GFCI and AFCI protection (Correct answer)

Correct answer: Both GFCI and AFCI protection

NEC 210.8(A)(10) requires GFCI protection for all 125-volt through 250-volt receptacles installed in laundry areas. Additionally, NEC 210.12(A) requires AFCI protection for branch circuits supplying outlets or devices in dwelling unit laundry areas. Therefore, both types of protection are mandatory.

Question 60: Per NEC 230.79(C), what is the minimum rating of the service disconnecting means for a one-family dwelling?

60 amperes
200 amperes
100 amperes (Correct answer)
150 amperes

Correct answer: 100 amperes

NEC 230.79(C) requires the service disconnecting means for a one-family dwelling to be rated at least 100 amperes, 3-wire. 60 A is the general minimum in 230.79(D) for other installations.

Question 61: What is the minimum calculated load for a 1,500 sq ft dwelling's general lighting before demand factors per NEC Table 220.12?

7,500 VA
6,000 VA
4,500 VA (Correct answer)
3,000 VA

Correct answer: 4,500 VA

1,500 sq ft × 3 VA/sq ft = 4,500 VA per NEC Table 220.12 for dwelling occupancies before any demand factors.

Question 62: EMT must be securely fastened within what distance of each outlet box, junction box, or conduit termination?

12 inches
18 inches
5 feet
3 feet (Correct answer)

Correct answer: 3 feet

NEC 358.30(A) requires EMT to be fastened within 3 ft of each box or termination and at least every 10 ft.

Question 63: Per NEC 250.97, where high-voltage (over 250V to ground) service conduit connections are made to enclosures, what is required?

Locknuts only are sufficient
No special bonding is required if locknuts are torqued properly
The conduit must be welded to the enclosure
Bonding jumpers around reducing washers and concentric or eccentric knockouts (Correct answer)

Correct answer: Bonding jumpers around reducing washers and concentric or eccentric knockouts

NEC 250.97 requires bonding jumpers to be used around reducing washers or impaired knockouts at over 250V services to ensure a reliable bond.

Question 64: What is the minimum standard size for a main bonding jumper conductor connecting the neutral bar to the equipment grounding bar in a 200-ampere residential service panel per NEC 250.28(D)?

8 AWG copper
6 AWG copper
2 AWG copper
4 AWG copper (Correct answer)

Correct answer: 4 AWG copper

For a 200A service with 2/0 AWG service conductors, Table 250.102(C)(1) yields a 4 AWG copper main bonding jumper minimum.

Question 65: NEC Article 550 covers mobile homes. What is the maximum ampere rating of the mobile home service equipment (main panel)?

200 amperes
150 amperes (Correct answer)
100 amperes
No maximum is specified

Correct answer: 150 amperes

NEC 550.11 requires that mobile home service equipment be rated at 100 amperes minimum, three-wire, 120/240-volt service.

Question 66: An individual branch circuit supplies a continuous-duty motor with a full-load current (FLA) of 30A. The circuit conductors are sized appropriately. According to NEC Article 430, what is the maximum standard size inverse-time circuit breaker that can be used for short-circuit and ground-fault protection for this motor?

40A
75A (Correct answer)
50A
60A

Correct answer: 75A

NEC Table 430.52 allows the rating of an inverse-time circuit breaker used for motor branch-circuit, short-circuit, and ground-fault protection to be a maximum of 250% of the motor's full-load current (FLA). For a 30A motor, the calculation is 30A x 2.50 = 75A. Since 75A is a standard size overcurrent device listed in NEC 240.6(A), it is the maximum permitted size.

Question 67: A 120V, 20A branch circuit supplies continuous loads only. What is the maximum allowable connected load in VA?

2,000 VA
1,800 VA
2,400 VA
1,920 VA (Correct answer)

Correct answer: 1,920 VA

NEC 210.19(A) and 210.20 require continuous loads not exceed 80% of circuit rating; 120V × 20A × 80% = 1,920 VA.

Question 68: What is the maximum total degrees of bends permitted in a run of EMT between pull points?

270 degrees
450 degrees
360 degrees (Correct answer)
180 degrees

Correct answer: 360 degrees

NEC 358.26 limits bends between pull points to the equivalent of four quarter bends, or 360 degrees total.

Question 69: The voltage waveform will lag behind the current waveform in a circuit supplying electricity to capacitive loads:

False
True (Correct answer)

Correct answer: True

In Capacitor Circuit Voltage waveform lags current waveform and has leading power factor. Inductive circuit will be exactly opposite

Question 70: NEC 240.4(B) allows using the next higher standard overcurrent device rating when a conductor's ampacity doesn't match a standard rating, as long as the device rating does not exceed what value?

800 A (Correct answer)
1200 A
600 A
400 A

Correct answer: 800 A

The next-size-up rule applies only when the overcurrent device is rated 800 A or less.

Question 71: For a constant load of 22 amperes at 750C, what size conductor should be used to protect against overcurrent?

12 THWN
8 THWN
10 THWN (Correct answer)
16 THWN

Correct answer: 10 THWN

A constant load implies a continuous load, requiring the conductor to be sized for 125% of the load. Thus, 22A * 1.25 = 27.5A. According to NEC Table 310.16 (75°C column for THWN), 12 AWG copper is rated for 25A (insufficient), while 10 AWG copper is rated for 30A. Therefore, 10 AWG THWN is the smallest conductor size that can safely carry a 27.5A continuous load.

Question 72: Arc-fault circuit-interrupter (AFCI) protection is required for 120-volt branch circuits supplying outlets in which area?

Bathrooms
Outdoors
Dwelling-unit bedrooms (Correct answer)
Detached garages only

Correct answer: Dwelling-unit bedrooms

NEC 210.12(A) requires AFCI protection for branch circuits serving dwelling bedrooms among other rooms.

Question 73: An electrician is installing nine current-carrying 10 AWG THHN copper conductors in a single conduit in an area with an ambient temperature of 30°C. What is the allowable ampacity of each conductor after applying the necessary adjustment factor from NEC Table 310.15(C)(1)?

20A (Correct answer)
28A
32A
40A

Correct answer: 20A

First, find the starting ampacity of 10 AWG THHN copper wire from the 90°C column of Table 310.16, which is 40A. Next, refer to Table 310.15(C)(1) for adjustment factors for more than three current-carrying conductors. For 7-9 conductors, the adjustment factor is 50%. Therefore, the final ampacity is 40A x 0.50 = 20A.

Question 74: For grounding electrode conductors, what is the minimum copper size required when connected to a metal underground water pipe with a 200A service?

8 AWG
6 AWG
2 AWG
4 AWG (Correct answer)

Correct answer: 4 AWG

Per NEC Table 250.66, a service with 3/0 to 350 kcmil conductors requires a 4 AWG copper grounding electrode conductor.

Question 75: What is the main concern when wiring in hazardous locations?

Lighting aesthetics
Humidity control
Preventing ignition sources (Correct answer)
Reducing cable length

Correct answer: Preventing ignition sources

When wiring in hazardous locations, the main concern is preventing electrical equipment from becoming an ignition source for flammable gases, vapors, or dusts. This requires specialized wiring methods, explosion-proof enclosures, and intrinsically safe systems to contain or prevent arcs, sparks, and excessive temperatures. The goal is to eliminate any potential source that could ignite the hazardous atmosphere.

Question 76: Per NEC Article 500, how is 'intrinsically safe' equipment defined for use in hazardous locations?

Equipment incapable of releasing sufficient energy to ignite a specific hazardous atmosphere (Correct answer)
Equipment that is double-insulated and operates ungrounded
Equipment rated for outdoor and wet locations
Equipment housed in explosion-proof metallic enclosures

Correct answer: Equipment incapable of releasing sufficient energy to ignite a specific hazardous atmosphere

Intrinsically safe equipment is designed so that under both normal and fault conditions it cannot release enough electrical or thermal energy to ignite a specific hazardous atmosphere.

Question 77: Where must the ungrounded and grounded conductors of each multiwire branch circuit be grouped?

At the point of origin (Correct answer)
At the load center exit only
At each receptacle
Grouping is not required

Correct answer: At the point of origin

NEC 210.4(D) requires conductors of each multiwire branch circuit to be grouped at the point of origin.

Question 78: What is the maximum spacing between countertop receptacles along a dwelling kitchen counter?

24 inches
36 inches
72 inches
48 inches (Correct answer)

Correct answer: 48 inches

NEC 210.52(C) requires receptacles so no point along the counter is more than 24 inches from one, yielding 48-inch maximum spacing.

Question 79: Which NEC article specifically covers grounding and bonding requirements?

Article 310
Article 230
Article 250 (Correct answer)
Article 220

Correct answer: Article 250

NEC Article 250 exclusively covers all grounding and bonding requirements for electrical systems.

Question 80: Kitchen wall countertop receptacles must be installed so no point along the wall line is more than how far, measured horizontally, from a receptacle?

18 inches
12 inches
36 inches
24 inches (Correct answer)

Correct answer: 24 inches

NEC 210.52(C)(1) requires that no point be more than 24 inches from a countertop receptacle.

National Electrical Code (NEC) Exam (Journeyman/Master Electrician)

The NEC exam assesses an electrician's knowledge of the National Electrical Code, which is the benchmark for safe electrical design, installation, and inspection to protect people and property from electrical hazards.

Questions

240 min

Time Limit

70%

To Pass

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