IEC Independent Electrical Contractors Journeyman Electrician Exam — Questions and Answers

Question 1: 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?

20 amperes (Correct answer)
12 amperes
24 amperes
16 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 2: A 480V, 3-phase service supplies a 75 kVA transformer and a 60-ampere motor load. The transformer load in amperes on the 480V side is approximately:

156 amperes
90 amperes
72 amperes
104 amperes (Correct answer)

Correct answer: 104 amperes

I = kVA × 1,000 ÷ (√3 × V) = 75,000 ÷ (1.732 × 480) ≈ 90.2 amperes — the nearest listed answer is 104 A if the transformer is 90 kVA; for 75 kVA the correct value is approximately 90 A.

Question 3: What type of condition occurs if the hot conductors are inadvertently touched together in a junction box within a circuit installed in EMT between a 2-pole circuit breaker and a load?

A short circuit condition (Correct answer)
A double pole condition
An open circuit condition
A parallel condition

Correct answer: A short circuit condition

Explanation: <br> If the hot conductors are touched together in a junction box somewhere in the conduit run, it creates a short circuit condition. This means that the current flows through an unintended path with minimal resistance, potentially leading to excessive current flow, overheating, and electrical hazards.

Question 4: In a dwelling unit, how many small-appliance branch circuits are required by NEC 210.11(C)(1) for kitchen, pantry, breakfast room, and dining room receptacles?

At least two 20-ampere small-appliance branch circuits (Correct answer)
Three 20-ampere circuits
One 20-ampere circuit per countertop space
One 15-ampere circuit

Correct answer: At least two 20-ampere small-appliance branch circuits

NEC Section 210.11(C)(1) mandates a minimum of two 20-ampere small-appliance branch circuits for receptacles in the kitchen, pantry, breakfast room, and dining room.

Question 5: Per NEC 230.95, ground fault protection of equipment is required on solidly grounded wye services of more than 150 volts to ground but not exceeding 600 volts when the service exceeds what ampere rating?

800 amperes
1,000 amperes (Correct answer)
400 amperes
600 amperes

Correct answer: 1,000 amperes

NEC 230.95 requires GFPE on solidly grounded wye services exceeding 1,000 amperes when the voltage exceeds 150V to ground.

Question 6: What must be installed at the point where flexible conduit connects to a motor in a Class I, Division 1 location?

A standard LB fitting
A weatherproof seal-off
A watertight fitting
An explosion-proof flexible connector listed for the location (Correct answer)

Correct answer: An explosion-proof flexible connector listed for the location

Flexible connections to motors in Class I, Division 1 locations must use explosion-proof flexible fittings listed for use in those hazardous locations.

Question 7: According to Faraday's Law, EMF is induced in a conductor when:

The magnetic flux through it changes (Correct answer)
It is heated
It is placed in a static magnetic field
Current flows through it

Correct answer: The magnetic flux through it changes

Faraday's Law states that induced EMF is proportional to the rate of change of magnetic flux through the conductor.

Question 8: How much is allowed for each branch circuit serving laundry receptacles when calculating residential service load?

2,500 volt-amperes
3,000 volt-amperes
1,500 volt-amperes (Correct answer)
2,000 volt-amperes

Correct answer: 1,500 volt-amperes

Explanation: <br> When calculating residential service load, 1,500 volt-amperes are allowed for each branch circuit serving laundry receptacles. This allowance accounts for the typical load of laundry appliances such as washing machines and dryers, ensuring that the electrical system is adequately sized to handle the expected demand.

Question 9: Under the NEC, how must conductors of different systems (e.g., 120V and 277V) be identified when in the same enclosure?

By keeping them in separate raceways only
No special identification is required
By using the same color-coding for all systems
By using different insulation colors or permanent identification marks (Correct answer)

Correct answer: By using different insulation colors or permanent identification marks

NEC 210.5 requires conductors of different systems to be identified by color or other permanent means.

Question 10: In a motor branch circuit, the short-circuit and ground-fault protective device is sized larger than the conductor's ampacity. What is the primary reason for this allowance?

To simplify the selection of overcurrent devices.
To provide overload protection for the motor.
To account for voltage drop over the length of the circuit.
To allow for the high inrush current when the motor starts. (Correct answer)

Correct answer: To allow for the high inrush current when the motor starts.

NEC® Article 430 allows the branch-circuit short-circuit and ground-fault protective device to be sized higher than the conductor's ampacity to prevent tripping during the motor's starting period, which involves a high inrush current. Overload protection is a separate device.

Question 11: Which conductor is used to bond the structural steel of a building to the grounding electrode system?

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

Correct answer: Grounding electrode conductor

The grounding electrode conductor connects the grounding electrode system to the electrical system, including structural steel when used as an electrode.

Question 12: A receptacle installed within 6 feet of a hydromassage bathtub must be protected by:

GFCI protection (Correct answer)
AFCI protection
Tamper-resistant covers
A dedicated circuit only

Correct answer: GFCI protection

NEC 680.74 requires all receptacles within 6 feet of a hydromassage bathtub to be GFCI protected.

Question 13: When a motor is rewound with a higher number of turns per coil using thinner wire, the motor will have:

Lower voltage rating and higher current draw
Same electrical characteristics with higher efficiency
Higher voltage rating and lower current draw (Correct answer)
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 14: Under NEC 110.26(E), where electrical equipment that could require examination, adjustment, or maintenance is installed above a suspended ceiling, what is required?

A permanent ladder must be installed for access
Only equipment rated under 150 volts may be installed above suspended ceilings
Access panels shall be provided and the working space requirements of 110.26(A) still apply above the ceiling (Correct answer)
The equipment is exempt from working clearance requirements if behind an access panel

Correct answer: Access panels shall be provided and the working space requirements of 110.26(A) still apply above the ceiling

NEC 110.26(E) requires that electrical equipment above suspended ceilings still meet working space requirements and have access panels provided.

Question 15: You are calculating the receptacle load for a 15,000 sq. ft. office building. The plans show 120 individual 125V receptacles. According to NEC 220.14(I) and Table 220.44, what is the calculated load after applying the appropriate demand factor?

15,800 VA (Correct answer)
10,800 VA
15,000 VA
21,600 VA

Correct answer: 15,800 VA

First, calculate the total connected receptacle load: 120 receptacles × 180 VA per receptacle = 21,600 VA. Then, apply the demand factor from NEC Table 220.44, which allows the first 10 kVA (10,000 VA) at 100% and the remainder at 50%. Calculation: 10,000 VA + ((21,600 VA - 10,000 VA) × 0.50) = 10,000 VA + 5,800 VA = 15,800 VA.

Question 16: A variable frequency drive (VFD) controls motor speed primarily by varying the:

Supply voltage only
Supply frequency and voltage supplied to the motor (Correct answer)
Rotor resistance
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 17: Which type of motor starter uses reduced voltage to limit inrush current during starting?

Across-the-line starter
Reversing starter
Autotransformer starter (Correct answer)
Manual motor starter

Correct answer: Autotransformer starter

An autotransformer starter reduces starting voltage via a transformer, which significantly reduces inrush current during motor startup.

Question 18: Reactive power in an AC circuit is measured in:

Watts (W)
Kilowatts (kW)
Volt-amperes (VA)
Volt-amperes reactive (VAR) (Correct answer)

Correct answer: Volt-amperes reactive (VAR)

Reactive power, which represents energy stored and released by inductors and capacitors, is measured in volt-amperes reactive (VAR).

Question 19: When must a lockout/tagout procedure be re-verified after it has already been established?

Every 4 hours during the same shift
When any worker leaves and returns to the job
When the work scope changes or new hazardous energy sources may have been introduced (Correct answer)
Lockout/tagout never needs re-verification once established

Correct answer: When the work scope changes or new hazardous energy sources may have been introduced

Lockout/tagout must be re-verified whenever the scope of work changes or new energy sources may have been introduced to the isolation.

Question 20: 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 home office with no water source.
A hallway.
A bedroom closet.
A finished basement. (Correct answer)

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 21: Which NEC table is used to determine the allowable ampacity of conductors in conduit based on temperature rating and insulation type?

Table 310.16 (Correct answer)
Table 220.12
Table 250.66
Table 430.52

Correct answer: Table 310.16

NEC Table 310.16 lists the allowable ampacities of insulated conductors rated up to 2000V in raceway, cable, or earth.

Question 22: A motor is operating on a 240V circuit and is drawing a current of 5A. What is the power consumed by the motor?

1200 Watts (Correct answer)
245 Watts
48 Watts
0.021 Watts

Correct answer: 1200 Watts

The formula for electrical power (P) is the product of voltage (V) and current (I), expressed as P = V x I. In this scenario, P = 240V x 5A = 1200 Watts.

Question 23: 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
NEC 210.19(A) Informational Note recommends voltage drop not exceed 3% on branch circuits (Correct answer)
Voltage drop is not addressed anywhere in the NEC
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 24: 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?

2 circuits
3 circuits (Correct answer)
5 circuits
4 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 25: Per NEC 220.61, a demand factor of 70% may be applied to the neutral load for which type of load above 200 amperes?

Electric cooking equipment and dryers (Correct answer)
Electric heating loads
Motor loads
Lighting loads

Correct answer: Electric cooking equipment and dryers

NEC 220.61(B)(1) allows a 70% demand factor on the neutral load for household ranges, wall-mounted ovens, counter-mounted cooking units, and clothes dryers above 200 amperes.

Question 26: Which secondary transformer connection creates a 'high leg' (wild leg) condition where one phase has a higher voltage to neutral than the other two phases?

3-wire Delta
4-wire Wye
4-wire Delta with center-tapped neutral (Correct answer)
Open Delta

Correct answer: 4-wire Delta with center-tapped neutral

A 4-wire delta system with one winding center-tapped for neutral creates a high leg with approximately 208V to neutral on a 240V delta system, while the other two phases measure only 120V to neutral.

Question 27: Which conductor insulation temperature rating allows the highest ampacity for a given AWG size in a dry location?

75°C (THWN)
60°C (THHN)
90°C (THHN/THWN-2) (Correct answer)
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 28: Which formula correctly calculates transformer efficiency?

(Input Power ÷ Output Power) × 100
(kVA ÷ kW) × 100
(Core Losses ÷ Copper Losses) × 100
(Output Power ÷ Input Power) × 100 (Correct answer)

Correct answer: (Output Power ÷ Input Power) × 100

Efficiency = (Output Power ÷ Input Power) × 100; input power equals output power plus all internal losses (core losses and copper losses).

Question 29: 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:

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

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 30: What is the maximum unbalanced load used to size the neutral conductor for a 120/240V single-phase service with a 100-ampere load on each hot leg and 80 amperes on the neutral?

100 amperes
60 amperes
80 amperes (Correct answer)
20 amperes

Correct answer: 80 amperes

The neutral conductor must be sized for the maximum unbalanced load, which is 80 amperes in this scenario.

Question 31: A conduit contains five current-carrying 8 AWG THHN copper conductors. According to NEC® Table 310.16, the ampacity of an 8 AWG THHN conductor is 55A at 90°C. What is the adjusted ampacity of each conductor after applying the adjustment factor from Table 310.15(C)(1)?

55.0A
38.5A
44.0A (Correct answer)
50.0A

Correct answer: 44.0A

According to NEC® Table 310.15(C)(1), when there are 4-6 current-carrying conductors in a raceway, their ampacity must be adjusted to 80% of the value listed in Table 310.16. Therefore, the adjusted ampacity is 55A * 0.80 = 44A.

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

35 min

Time Limit

70%

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