IEC Independent Electrical Contractors Journeyman Electrician Exam — Questions and Answers

Question 1: An electrician installs a 120/240V single-phase multiwire branch circuit using two single-pole circuit breakers. To comply with NEC® 210.4(B), what additional component is required at the panelboard where the circuit originates?

A surge protection device.
An arc-fault circuit interrupter for each pole.
An identified handle tie. (Correct answer)
A grounding clip for each breaker.

Correct answer: An identified handle tie.

NEC® 210.4(B) requires that each multiwire branch circuit be provided with a means that will simultaneously disconnect all ungrounded conductors at the point where the branch circuit originates. This can be achieved with a 2-pole circuit breaker or by using two single-pole circuit breakers with an identified handle tie to connect the operating handles.

Question 2: When installing insulated equipment grounding conductors of size 6 AWG or smaller, what color(s) must the conductor's continuous outer finish be?

Any color except white, gray, or green
White or Gray
Green or green with one or more yellow stripes (Correct answer)
Black or Red

Correct answer: Green or green with one or more yellow stripes

NEC Section 250.119 states that individually covered or insulated equipment grounding conductors must have a continuous outer finish that is either green or green with one or more yellow stripes. [11, 15] White or gray is reserved for grounded (neutral) conductors, and other colors are typically used for ungrounded (hot) conductors. [13, 16]

Question 3: Which of the following best describes impedance in an AC circuit?

The capacitive reactance only
The inductive reactance only
The total opposition to AC current flow including resistance and reactance (Correct answer)
The DC resistance only

Correct answer: The total opposition to AC current flow including resistance and reactance

Impedance (Z) is the total opposition to AC current and is the vector sum of resistance and reactance.

Question 4: In a star-delta (wye-delta) motor starting method, the motor initially starts in wye and then switches to delta. What is the starting current relative to across-the-line starting?

Reduced to 2/3 of full-voltage starting current
Equal to full-voltage starting current
Reduced to 1/3 of full-voltage starting current (Correct answer)
Reduced to 1/2 of full-voltage starting current

Correct answer: Reduced to 1/3 of full-voltage starting current

Wye-delta starting reduces the starting current to 1/3 of full-voltage (across-the-line) starting current.

Question 5: A dwelling has 3,500 sq ft of living space. Using NEC 220.12, what is the general lighting load at 3 VA per sq ft?

8,000 VA
12,000 VA
10,500 VA (Correct answer)
7,000 VA

Correct answer: 10,500 VA

3,500 sq ft × 3 VA/sq ft = 10,500 VA for general lighting and receptacle loads.

Question 6: What is the phase angle in a circuit with R = 30 Ω and XL = 40 Ω?

36.9°
53.1° (Correct answer)
60°
45°

Correct answer: 53.1°

θ = arctan(XL/R) = arctan(40/30) = arctan(1.333) ≈ 53.1°.

Question 7: What is the minimum size copper conductor required for a branch circuit serving a single 240-volt, 30-ampere receptacle?

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

Correct answer: 10 AWG

A 30-ampere circuit requires 10 AWG copper conductors as specified in NEC Table 310.12.

Question 8: Under NFPA 70E, what is the incident energy analysis method used to determine arc flash PPE requirements?

Visual inspection by a safety officer
Hazard Risk Category (HRC) table lookup only
Calculated incident energy based on system fault current, working distance, and clearing time (Correct answer)
Manufacturer's label on the equipment

Correct answer: Calculated incident energy based on system fault current, working distance, and clearing time

Incident energy analysis calculates the actual energy exposure based on system fault current, arcing duration, and working distance to select appropriate PPE.

Question 9: What is the minimum depth requirement for installing underground feeder cable in PVC conduit under a building?

At least 12 inches deep
At least 8 inches deep
At least 0 inches deep (Correct answer)
At least 24 inches deep

Correct answer: At least 0 inches deep

Explanation: <br> Underground feeder cable in PVC under a building must be installed at least 0 inches deep. The cable is typically installed in a PVC conduit, which provides mechanical protection. However, local codes may vary, so it's essential to consult with local regulations to ensure compliance.

Question 10: What is required when a cable passes through a metal wall stud or joist to prevent damage to the cable?

A conduit sleeve at least 6 inches long
A cable strap within 12 inches on each side
A listed bushing or grommet (Correct answer)
Nothing is required for metal studs

Correct answer: A listed bushing or grommet

NEC 300.4(B) requires a listed bushing or grommet when NM cable passes through a metal stud or joist.

Question 11: When calculating the service load for four household clothes dryers in an apartment building, what demand factor does NEC Table 220.54 apply?

70%
80% (Correct answer)
100%
85%

Correct answer: 80%

NEC Table 220.54 specifies an 80% demand factor when calculating the load for 4 clothes dryers.

Question 12: What is plugging as a method of motor braking?

Reversing the phase sequence of the motor while it is running to create braking torque (Correct answer)
Removing power and allowing the motor to coast to a stop
Applying DC to the stator after disconnecting AC power
Using a mechanical friction brake

Correct answer: Reversing the phase sequence of the motor while it is running to create braking torque

Plugging reverses the phase sequence applied to the motor while it is still rotating, creating a reverse rotating field that produces braking torque.

Question 13: For service entrance conductors, NEC 230.42 requires that the conductor ampacity must not be less than what percentage of the calculated load?

80%
125%
115%
100% (Correct answer)

Correct answer: 100%

NEC 230.42(A) requires service entrance conductors to have an ampacity not less than the calculated load (100%).

Question 14: What is the minimum required ampacity for a branch circuit conductor supplying a continuous load of 22A and a noncontinuous load of 10A?

27.5A
37.5A (Correct answer)
40.0A
32.0A

Correct answer: 37.5A

Per NEC® 210.19(A)(1), branch-circuit conductors must have an ampacity not less than the sum of the noncontinuous load plus 125% of the continuous load. The calculation is: (22A * 1.25) + 10A = 27.5A + 10A = 37.5A.

Question 15: Two 100W, 120V incandescent lamps are connected in series across 120V. What is the total power consumed?

50W (Correct answer)
25W
200W
100W

Correct answer: 50W

Each lamp's resistance = 120²/100 = 144Ω; series total = 288Ω; P = 120²/288 = 50W.

Question 16: A 240-volt, single-phase motor draws 18 amperes at full load. What is the minimum size inverse-time circuit breaker permitted for branch circuit protection per NEC?

30 amperes
20 amperes
40 amperes
45 amperes (Correct answer)

Correct answer: 45 amperes

NEC 430.52 allows inverse-time breakers to be sized up to 250% of FLC; 18A × 250% = 45A, which is a standard size.

Question 17: A single-phase 120/240V residential service has a calculated load of 23,500 VA. What minimum standard service size in amperes is required?

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

Correct answer: 150 amperes

23,500 VA ÷ 240 V = 97.9 A; the next standard size above 100 A that covers this load is 150 amperes.

Question 18: Which insulation type is listed for use in wet locations as well as dry locations, making it suitable for outdoor branch circuit wiring in conduit?

THWN (Correct answer)
THHN
RHH
TW

Correct answer: THWN

THWN (Thermoplastic, Heat- and Moisture-Resistant, Nylon-jacketed) insulation is listed for both wet and dry locations and is commonly used in outdoor conduit runs.

Question 19: A 3-phase, 4-wire, 208Y/120V commercial service supplies 15 kW of lighting. Using NEC 220.12 at 3.5 VA/sq ft, the building is approximately how many square feet?

5,000 sq ft
3,571 sq ft
4,286 sq ft (Correct answer)
6,000 sq ft

Correct answer: 4,286 sq ft

15,000 VA ÷ 3.5 VA/sq ft ≈ 4,286 sq ft for the office/commercial occupancy.

Question 20: A 120-volt, 20-ampere branch circuit feeds a small office. What is the maximum computed load allowed on this circuit for non-continuous loads?

24 amperes
16 amperes
20 amperes (Correct answer)
12 amperes

Correct answer: 20 amperes

Non-continuous loads may use 100% of the circuit rating, so a 20-ampere circuit can carry up to 20 amperes of non-continuous load.

Question 21: What is the resonant frequency of a series LC circuit with L = 50mH and C = 50µF?

200 Hz
31.8 Hz (Correct answer)
50 Hz
100.7 Hz

Correct answer: 31.8 Hz

f = 1 / (2π√LC) = 1 / (2π√(0.05 × 0.00005)) ≈ 31.8 Hz.

Question 22: If a metal underground water pipe is used as a grounding electrode, what is the minimum buried length required by NEC 250.52(A)(1)?

5 feet
10 feet (Correct answer)
20 feet
8 feet

Correct answer: 10 feet

NEC 250.52(A)(1) requires a metal underground water pipe electrode to have at least 10 feet of direct burial contact with the earth.

Question 23: When running NM cable through a 2x4 wood stud, the hole must be drilled at what minimum distance from the edge of the stud to avoid requiring a nail plate?

1 inch
1-1/4 inches (Correct answer)
2 inches
1-1/2 inches

Correct answer: 1-1/4 inches

NEC 300.4(A)(1) requires holes for cables through wood framing members to be at least 1-1/4 inches from the nearest edge, or a nail plate must be installed.

Question 24: A branch circuit runs 150 feet from the panelboard to a 120V, 10-ampere load. Which NEC guideline addresses keeping voltage drop within acceptable limits?

NEC 310.15 mandates a maximum 5% voltage drop for all circuits
Voltage drop is not addressed anywhere in the NEC
NEC 210.19(A) Informational Note recommends voltage drop not exceed 3% on branch circuits (Correct answer)
NEC 220.12 sets a hard 2% limit for branch circuits

Correct answer: NEC 210.19(A) Informational Note recommends voltage drop not exceed 3% on branch circuits

NEC Section 210.19(A) contains an Informational Note recommending that voltage drop on branch circuits not exceed 3% to maintain efficiency and equipment performance.

Question 25: A bonding jumper installed on the load side of the service to connect multiple equipment grounding conductors is called a(n):

Main bonding jumper
System bonding jumper
Grounding electrode conductor
Equipment bonding jumper (Correct answer)

Correct answer: Equipment bonding jumper

An equipment bonding jumper is used on the load side of the service to ensure electrical continuity between multiple equipment grounding conductors or enclosures.

Question 26: Ground-fault protection of equipment (GFPE) per NEC 230.95 is required on solidly grounded wye services of more than 150V to ground but not exceeding 600V phase-to-phase when the service rating is at least:

1000A
800A (Correct answer)
600A
400A

Correct answer: 800A

NEC 230.95 requires GFPE on services rated 800A or more on solidly grounded wye systems meeting the voltage criteria.

Question 27: Which of the following areas in a commercial garage is classified as a Class I, Division 2 hazardous location?

Office area above the garage
Area up to 18 inches above the floor (Correct answer)
Outdoor parking lot surface
Ventilated storage room above grade

Correct answer: Area up to 18 inches above the floor

In commercial garages, the area from floor level to 18 inches above the floor is classified Class I, Division 2 due to heavier-than-air gasoline vapors.

Question 28: What is the NEC-required minimum clearance from the top of a window opening for service-entrance conductors or overhead branch circuit spans?

10 feet (3.0 m)
No clearance required if conductors are insulated
4 feet (1.2 m)
3 feet (900 mm) (Correct answer)

Correct answer: 3 feet (900 mm)

NEC Section 230.9 requires service conductors to maintain at least 3 feet (900 mm) clearance from windows that can be opened, as well as from doors and similar openings.

Question 29: What is the calculated load for a 4,000 sq ft commercial office building at 3.5 VA/sq ft for lighting plus two 20-ampere, 120-volt receptacle circuits at 180 VA per outlet with 10 outlets each?

17,600 VA (Correct answer)
17,200 VA
14,000 VA
18,000 VA

Correct answer: 17,600 VA

Lighting: 4,000 × 3.5 = 14,000 VA; receptacles: 2 circuits × 10 outlets × 180 VA = 3,600 VA; total = 17,600 VA.

Question 30: When calculating the demand load for a residential range rated at 12 kW, what demand factor does NEC Table 220.55 apply for a single range?

70%
100%
80%
8 kW (Column C value) (Correct answer)

Correct answer: 8 kW (Column C value)

NEC Table 220.55, Column C assigns 8 kW demand for a single household cooking appliance rated 12 kW or less.

Question 31: How many 15-ampere, 120-volt branch circuits are required per NEC for general lighting in a 2,400 sq ft dwelling unit using a 3 VA/sq ft load?

5 circuits
4 circuits
3 circuits (Correct answer)
2 circuits

Correct answer: 3 circuits

2,400 sq ft × 3 VA/sq ft = 7,200 VA ÷ 120V = 60A ÷ 15A per circuit = 4 circuits, but NEC 210.11 requires a minimum of 3 circuits for this size; rounding yields 3 circuits minimum.

Question 32: An electrician is calculating the service for a single-family dwelling using the optional method per NEC Article 220, Part IV. The total calculated general load is 32,000 VA. How is the demand factor applied to this load?

The entire 32,000 VA is taken at 100%
The first 10,000 VA at 100%, and the remainder at 40% (Correct answer)
The entire 32,000 VA is taken at 65%
The first 3,000 VA at 100%, and the remainder at 35%

Correct answer: The first 10,000 VA at 100%, and the remainder at 40%

NEC 220.82(B) specifies the demand factor for the optional method calculation for a dwelling unit. The first 10,000 VA of the general load is calculated at 100%, and the remainder of the load is calculated at 40%. So, (10,000 VA * 1.0) + ((32,000 VA - 10,000 VA) * 0.40) = 10,000 VA + 8,800 VA = 18,800 VA.

Question 33: When installing EMT in a corrosive environment, which protection method is required?

The EMT must be wrapped in PVC tape
A different wiring method suitable for corrosive conditions must be used or the EMT must be listed for the environment (Correct answer)
No additional protection is needed; EMT is inherently corrosion-resistant
The EMT must be painted with an approved corrosion-resistant coating

Correct answer: A different wiring method suitable for corrosive conditions must be used or the EMT must be listed for the environment

NEC 358.10(B) states that EMT shall not be used where subject to severe corrosive influences unless protected by a corrosion-resistant material or a different method is used.

Question 34: Mobile home parks must provide each lot with at least a minimum electrical service of:

200-ampere, 120/240-volt
50-ampere, 120/240-volt (Correct answer)
30-ampere, 120-volt
100-ampere, 120/240-volt

Correct answer: 50-ampere, 120/240-volt

NEC 550.30 requires each mobile home lot to be supplied with a minimum 50-ampere, 120/240-volt service.

Question 35: What is the requirement under NEC 110.26(A)(2) regarding the width of dedicated electrical space above a panelboard?

The width of the panelboard plus 12 inches on each side
The width of the equipment extending from the floor or structural ceiling to a height of 6 feet above the equipment or to the structural ceiling, whichever is lower (Correct answer)
The width of the panelboard to a height of 3 feet above the top
No specific height requirement above the panel width

Correct answer: The width of the equipment extending from the floor or structural ceiling to a height of 6 feet above the equipment or to the structural ceiling, whichever is lower

NEC 110.26(E)(1) requires dedicated electrical space above equipment that extends the width of the equipment to a height of 6 feet or to the structural ceiling.

Question 36: An electrician is installing a 200A, 240V single-phase service disconnecting means in a commercial building. The calculated available fault current is 8,500A. What is the minimum interrupting rating required for this disconnect?

5,000A
8,500A
22,000A
10,000A (Correct answer)

Correct answer: 10,000A

Per NEC 110.9, equipment intended to interrupt current at fault levels must have an interrupting rating at least equal to the current that is available at the line terminals of the equipment. Since the available fault current is 8,500A, a standard 10,000A rated device would be the next highest standard size and would meet this requirement.

Question 37: A 20-ampere, 120-volt branch circuit supplies multiple receptacle outlets. What is the maximum load that may be connected continuously?

20 amperes
24 amperes
12 amperes
16 amperes (Correct answer)

Correct answer: 16 amperes

Continuous loads on a branch circuit must not exceed 80% of the circuit rating, so 80% of 20A = 16 amperes.

Question 38: An electrician needs to connect two 1/2 HP, 120V motors on a single 20A branch circuit in a workshop. The FLC for each motor is 9.8A, but the nameplate FLA is 5.8A. Under what condition is this installation permitted by NEC 430.53(A)?

The branch-circuit protective device rating is not exceeded, and the FLC of each motor is less than 10A.
This installation is never permitted; each motor requires its own branch circuit.
The nameplate FLA of each motor does not exceed 6 amperes, and each motor has individual overload protection. (Correct answer)
As long as the combined FLC (11.6A) is less than 80% of the breaker rating.

Correct answer: The nameplate FLA of each motor does not exceed 6 amperes, and each motor has individual overload protection.

NEC 430.53(A) allows two or more motors on a single 120V, 20A branch circuit if several conditions are met. Key among these are that each motor's full-load current rating does not exceed 6 amperes (based on nameplate), and each motor has its own individual overload protection as per 430.32.

Question 39: Which NEC section governs the maximum number of receptacles permitted on a 15- or 20-ampere branch circuit in a commercial occupancy?

NEC does not limit the number; load calculations govern (Correct answer)
NEC 210.24
NEC 210.21
NEC 220.14(I) limits to 6 per circuit

Correct answer: NEC does not limit the number; load calculations govern

The NEC does not set a maximum number of receptacles on commercial branch circuits; instead, the total calculated load (180 VA per receptacle per NEC 220.14) must not exceed the circuit capacity.

Question 40: Shore power receptacles at a marina must be located within how many feet of the boat slip they serve?

20 feet (Correct answer)
30 feet
10 feet
50 feet

Correct answer: 20 feet

NEC 553.11 requires shore power receptacles to be located within 20 feet of the bow or stern of the boat slip they serve.

Question 41: When sizing the service for a commercial occupancy with 50,000 VA of connected lighting, what demand factor applies to the first 20,000 VA per NEC Table 220.42?

50%
80%
75%
100% (Correct answer)

Correct answer: 100%

NEC Table 220.42 applies 100% to the first 20,000 VA of lighting load for commercial occupancies.

Question 42: What is the inductive reactance of a 0.5H inductor at 60Hz?

376.9Ω
188.5Ω (Correct answer)
30Ω
120Ω

Correct answer: 188.5Ω

XL = 2πfL = 2π × 60 × 0.5 ≈ 188.5Ω.

Question 43: What is the minimum size copper equipment grounding conductor required for a 60-ampere circuit per NEC Table 250.122?

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

Correct answer: #8 AWG

NEC Table 250.122 requires a minimum #8 AWG copper equipment grounding conductor for circuits rated up to 60 amperes.

Question 44: What is the minimum amp rating for the service disconnect of a single-family dwelling with a computed load of 10 KVA?

200 amps
300 amps
100 amps (Correct answer)
150 amps

Correct answer: 100 amps

Explanation: <br> For a single-family dwelling with a computed load of 10 KVA, the minimum size service disconnect is 100 amps. This is based on typical residential service requirements and is sufficient to handle the expected electrical demand of the dwelling.

Question 45: A 10kW continuous resistive load on 240V single-phase requires a circuit breaker sized at 125%. What is the minimum standard breaker size?

70A
60A (Correct answer)
50A
40A

Correct answer: 60A

I = 10,000/240 = 41.67A; × 1.25 = 52.08A; the next standard breaker size above 52A is 60A.

Question 46: What is the minimum bending radius for a 1-inch rigid metal conduit (RMC)?

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

Correct answer: 6 inches

NEC Table 344.24 requires a minimum bending radius of 6 times the trade size for 1-inch RMC, which equals 6 inches.

Question 47: A power factor correction capacitor bank is added to a facility. The primary benefit is:

Increasing system voltage above rated levels
Eliminating harmonic distortion
Reducing true (real) power consumption
Reducing reactive power demand and improving power factor (Correct answer)

Correct answer: Reducing reactive power demand and improving power factor

Capacitor banks supply reactive power locally, reducing reactive current from the utility and improving power factor.

Question 48: Which conductor insulation temperature rating allows the highest ampacity for a given AWG size in a dry location?

90°C (THHN/THWN-2) (Correct answer)
75°C (THWN)
60°C (THHN)
105°C (MTW)

Correct answer: 90°C (THHN/THWN-2)

A 90°C-rated insulation (such as THHN or THWN-2 in dry locations) permits the highest ampacity table values for a given conductor size.

Question 49: Type TC (Tray Cable) is most commonly installed in which environment?

Underground direct burial
Inside metallic conduit only
Concealed in walls of residential buildings
Open cable tray systems in industrial facilities (Correct answer)

Correct answer: Open cable tray systems in industrial facilities

Type TC cable is specifically designed and listed for use in cable tray systems, per NEC Article 336.

Question 50: How should two identical 24-volt loads be connected to a single 24-volt battery to ensure they receive the correct voltage?

In a series connection
In a parallel connection (Correct answer)
In a short circuit connection
In an ungrounded connection

Correct answer: In a parallel connection

Explanation: <br> To ensure that each load receives the correct voltage from the 24-volt battery, the loads should be connected in parallel. In a parallel connection, each load has its path to the battery, allowing it to operate independently and receive the full voltage provided by the battery.

Question 51: Which NEC article covers marinas and boatyards?

Article 553
Article 553
Article 553
Article 553 (Correct answer)

Correct answer: Article 553

NEC Article 553 covers floating buildings, while Article 553 is actually for floating buildings—marinas and boatyards are covered by Article 553.

Question 52: What is the maximum voltage drop recommended by the NEC for branch circuits serving general loads?

10%
3% (Correct answer)
5%
2%

Correct answer: 3%

NEC 210.19(A) informational note recommends keeping branch circuit voltage drop to 3% or less.

Question 53: What gauge is the smallest copper conductor permitted for branch circuits under NEC Article 210?

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

Correct answer: 14 AWG

NEC Section 210.19 permits 14 AWG copper as the minimum conductor size for branch circuits, which corresponds to a 15-ampere rating.

Question 54: Under the NEC optional method for dwelling units (220.82), what percentage is applied to the load above the initial 10 kVA?

50%
40% (Correct answer)
60%
25%

Correct answer: 40%

NEC 220.82(B) applies 40% to all loads above the first 10 kVA when using the optional calculation method.

Question 55: A variable frequency drive (VFD) controls motor speed primarily by varying the:

Supply frequency and voltage supplied to the motor (Correct answer)
Rotor resistance
Supply voltage only
Number of motor poles

Correct answer: Supply frequency and voltage supplied to the motor

VFDs control motor speed by simultaneously varying the output frequency and voltage (maintaining a constant V/Hz ratio) supplied to the motor.

Question 56: Which type of fuse is designed to open on sustained overloads but NOT on normal motor starting currents?

Type S fuse
Cartridge fuse
Time-delay fuse (Correct answer)
One-time fuse

Correct answer: Time-delay fuse

Time-delay (dual-element) fuses tolerate short-duration inrush currents while still protecting against sustained overloads.

Question 57: A 3-phase, 4-wire, 208Y/120V system with an 800A main breaker is required to have GFPE per NEC 230.95. The maximum GFPE trip setting allowed is:

1000A
100A (Correct answer)
300A
1200A

Correct answer: 100A

NEC 230.95(A) limits the maximum GFPE trip setting to 1200A and the maximum setting is 1200A, but trip current must not exceed 1200A; the maximum trip setting is 1200A — however, NEC 230.95 sets the maximum at 1200A with a maximum setting of 1200A, and the code maximum for the trip level is 1200A.

Question 58: What is the purpose of a neutral conductor on a multiwire branch circuit?

It limits voltage drop on long runs
It provides equipment grounding
It carries the unbalanced load current and completes the circuit (Correct answer)
It carries fault current to ground

Correct answer: It carries the unbalanced load current and completes the circuit

The neutral on a multiwire branch circuit carries the difference (unbalanced) current between the two hot conductors and completes the return path.

Question 59: A motor's power factor is 0.75 lagging. To correct the power factor to near unity, you would install:

A larger overload relay
Capacitors in parallel with the motor (Correct answer)
Inductors in series with the motor
A resistor bank across the motor terminals

Correct answer: Capacitors in parallel with the motor

Capacitors supply reactive power locally, offsetting the lagging reactive power demand of inductive motors and improving the overall power factor.

Question 60: Under NEC Article 210, which branch circuit type is required for bathroom receptacles in a dwelling unit?

20-ampere circuit dedicated to bathroom receptacles (Correct answer)
Any GFCI-protected circuit is acceptable
15-ampere general-purpose circuit
30-ampere circuit for high-load appliances

Correct answer: 20-ampere circuit dedicated to bathroom receptacles

NEC Section 210.11(C)(3) requires at least one 20-ampere branch circuit dedicated to bathroom receptacles in dwelling units.

Question 61: What is the purpose of a motor's overload relay?

To prevent the motor from starting under load
To protect against phase reversal
To protect the motor from voltage surges
To protect the motor from sustained overcurrent due to overloading (Correct answer)

Correct answer: To protect the motor from sustained overcurrent due to overloading

Overload relays protect motors from sustained overcurrents caused by mechanical overloads, which generate excess heat and can damage windings.

Question 62: What is the minimum calculated load for a show-window lighting circuit that runs along a 40-foot base in a retail store, before accounting for it as a continuous load?

1,200 VA
3,000 VA
6,000 VA
8,000 VA (Correct answer)

Correct answer: 8,000 VA

According to NEC 220.46(A), the load for show-window lighting shall be calculated at not less than 200 VA per linear foot. Therefore, the calculation is 40 feet × 200 VA/foot = 8,000 VA. The 125% multiplier for continuous loads would be applied later when sizing the overcurrent protection and conductors, not for this initial load calculation.

Question 63: In a theater, what is the required clearance above the stage floor for equipment operating over 150 volts to ground?

10 feet
7 feet
12 feet
8 feet (Correct answer)

Correct answer: 8 feet

NEC Article 520 requires a minimum 8-foot clearance above the stage floor for exposed live parts over 150 volts in theaters.

Question 64: An electrician is installing Electrical Nonmetallic Tubing (ENT) in the walls of a new wood-frame residential construction. What is the maximum spacing interval required for securing and supporting the ENT?

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

Correct answer: 3 feet

Per NEC Article 362.30(A), Electrical Nonmetallic Tubing (ENT) must be securely fastened at intervals not exceeding 3 feet (900 mm). Additionally, it must be secured within 3 feet of every outlet box, junction box, cabinet, or fitting. [10, 22, 23]

Question 65: A multiwire branch circuit in a dwelling unit must have a means to simultaneously disconnect all ungrounded conductors. Which NEC section requires this?

310.15(B)
220.42
250.130(C)
210.4(B) (Correct answer)

Correct answer: 210.4(B)

NEC Section 210.4(B) requires that each multiwire branch circuit in a dwelling unit be provided with a means to simultaneously disconnect all ungrounded conductors at the panelboard.

Question 66: What is the effect of raising the ambient temperature above 30°C (86°F) on a conductor's allowable ampacity?

Ampacity is unchanged; temperature ratings are absolute limits
Ampacity increases because heat dissipates faster
Ampacity is limited only by conduit fill, not ambient temperature
Ampacity must be derated using the correction factors in NEC Table 310.15(B)(1) (Correct answer)

Correct answer: Ampacity must be derated using the correction factors in NEC Table 310.15(B)(1)

Higher ambient temperatures reduce a conductor's ability to dissipate heat, requiring a correction factor from NEC Table 310.15(B)(1) to derate the allowable ampacity.

Question 67: What is the unit of magnetic flux?

Gauss
Tesla
Weber (Correct answer)
Henry

Correct answer: Weber

The Weber (Wb) is the SI unit of magnetic flux, where 1 Wb = 1 V·s.

Question 68: Which NEC article specifically covers grounding and bonding requirements?

Article 300
Article 250 (Correct answer)
Article 230
Article 200

Correct answer: Article 250

NEC Article 250 contains all general requirements for grounding and bonding of electrical installations.

Question 69: A motor disconnecting means must be within sight of the motor and its driven machinery. 'Within sight' is defined by the NEC as visible and not more than:

100 feet
75 feet
50 feet (Correct answer)
25 feet

Correct answer: 50 feet

Per NEC 430.102, 'within sight' means visible and not more than 50 feet distant from the motor and driven machinery.

Question 70: When is it permissible to use 10 AWG copper on a 30-ampere branch circuit per NEC Article 210?

Never; 10 AWG copper is only rated 30A on a feeder
When the run is less than 50 feet to limit voltage drop
When the circuit supplies a single receptacle rated 30 amperes (Correct answer)
When the 10 AWG conductor has a 90°C insulation rating

Correct answer: When the circuit supplies a single receptacle rated 30 amperes

NEC Section 210.21(B) permits a single 30-ampere receptacle outlet to be supplied by 10 AWG copper (30A at 75°C) on a 30-ampere branch circuit.

Question 71: A 400-ampere service has a calculated load of 320 amperes. The neutral calculated load is 210 amperes. What is the neutral ampacity after applying the NEC 220.61 reduction?

147 amperes
210 amperes
168 amperes
200 amperes + 7 amperes = 207 amperes (Correct answer)

Correct answer: 200 amperes + 7 amperes = 207 amperes

200 A at 100% = 200 A; (210 A − 200 A) × 70% = 7 A; total neutral = 207 amperes per NEC 220.61.

Question 72: Per NEC 240.4(B), the next standard OCPD size above the conductor ampacity may be used only when the conductor ampacity does NOT exceed:

600A (Correct answer)
800A
400A
1000A

Correct answer: 600A

NEC 240.4(B) permits the next larger standard OCPD when the conductor ampacity is 600A or less and the OCPD is not for a motor or similar load.

Question 73: According to NEC® 210.8(A), which of the following areas in a newly constructed dwelling unit requires GFCI protection for all 125V, single-phase, 15- and 20-ampere receptacles?

A bedroom closet.
A finished basement. (Correct answer)
A home office with no water source.
A hallway.

Correct answer: A finished basement.

Recent updates to NEC® 210.8(A)(5) have expanded the requirement for GFCI protection to include ALL basement areas in dwelling units, whether they are finished or unfinished. Hallways, closets, and typical home offices do not have a specific requirement for GFCI protection unless other conditions apply (e.g., proximity to a sink).

Question 74: What is the maximum distance between supports for 1-inch rigid PVC conduit (Schedule 40) installed horizontally?

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

Correct answer: 5 feet

NEC Table 352.30(B) requires horizontal supports for 1-inch Schedule 40 PVC conduit at maximum 5-foot intervals.

Question 75: The power factor of a purely resistive circuit is:

1.0 (Correct answer)
0
0.707
0.5

Correct answer: 1.0

A purely resistive circuit has no reactive power, so PF = real power / apparent power = 1.0.

Question 76: A 75 kVA, three-phase, 480V/208Y/120V transformer is operating at full load. What is the approximate full-load secondary line current?

208A (Correct answer)
156A
360A
104A

Correct answer: 208A

Full-load secondary current = kVA × 1,000 ÷ (secondary line voltage × √3) = 75,000 ÷ (208 × 1.732) ≈ 208A.

Question 77: What is the minimum headroom required above the working space for electrical panelboards supplying branch circuits in commercial occupancies?

6.0 feet (1.8 m) or the height of the equipment, whichever is greater (Correct answer)
8.0 feet (2.4 m)
7.0 feet (2.1 m)
5.5 feet (1.7 m)

Correct answer: 6.0 feet (1.8 m) or the height of the equipment, whichever is greater

NEC Section 110.26(A)(3) requires a minimum headroom of 6.0 feet or the height of the equipment, whichever is greater, in front of electrical equipment.

Question 78: When a motor is rewound with a higher number of turns per coil using thinner wire, the motor will have:

Same electrical characteristics with higher efficiency
Higher voltage rating and lower current draw (Correct answer)
Lower voltage rating and higher current draw
Same voltage but higher starting torque

Correct answer: Higher voltage rating and lower current draw

More turns increase the winding impedance, raising the voltage required and reducing the current drawn for equivalent power output.

Question 79: What factor primarily determines the voltage drop on a branch circuit conductor run?

Number of splices in the run
Insulation color
Conductor length and load current (Correct answer)
Type of conduit used

Correct answer: Conductor length and load current

Voltage drop is primarily a function of conductor resistance (related to length and wire gauge) multiplied by the load current.

Question 80: When must tap conductors be protected by an overcurrent device at the point where they receive their supply?

Only when the tap feeds a motor
Exceptions in NEC 240.21 allow unprotected taps under specific length and ampacity conditions (Correct answer)
Always, with no exceptions
Only when the tap exceeds 10 feet

Correct answer: Exceptions in NEC 240.21 allow unprotected taps under specific length and ampacity conditions

NEC Section 240.21 provides tap conductor exceptions that allow conductors to be run without overcurrent protection at the source under defined length and ampacity rules.

IEC Independent Electrical Contractors Journeyman Electrician Exam

The IEC (Independent Electrical Contractors) journeyman electrician exam tests knowledge of the National Electrical Code (NEC), electrical theory, wiring methods, conductors, branch circuits, motor controls, and electrical calculations required for journeyman electrician licensure.

Questions

240 min

Time Limit

70%

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