Illinois Electrical Contractor Exam
Practice Questions and Correct Answers
(Verified Answers) Plus Rationales 2027
Q&A | Instant Download Pdf
Electrical Principles, Safety, and Chicago Electrical Code
1. Which unit is used to express electrical power?
A. Ohm
B. Ampere
C. Watt
D. Coulomb
Answer: C
Rationale: The watt is the unit of electrical power. Power in a DC circuit can be
calculated as P = E × I, where P is watts, E is volts, and I is amperes.
2. A balanced 3-phase load operates at 208 volts line-to-line and draws 30
amperes at unity power factor. Approximately how much apparent power does
the load use?
A. 10.8 kVA
B. 17.3 kVA
C. 24.0 kVA
D. 36.0 kVA
Answer: B
Rationale: For a balanced three-phase system, apparent power is S = √3 × V × I.
Therefore, S = 1.732 × 208 × 30 ≈ 10,804 VA, or about 10.8 kVA. The correct
answer is actually A.
,Correct Answer: A
Rationale: The three-phase apparent-power formula is S = √3 × V × I. Using 208
volts and 30 amperes gives approximately 10.8 kVA.
3. What happens to voltage drop when conductor resistance increases while
circuit current remains constant?
A. Voltage drop decreases
B. Voltage drop increases
C. Voltage drop becomes zero
D. Voltage drop becomes independent of resistance
Answer: B
Rationale: Voltage drop is calculated using E = I × R. If current remains constant,
increasing resistance directly increases the voltage drop.
4. A transformer has 480 volts on its primary and 120 volts on its secondary.
What type of transformer is this?
A. Step-down transformer
B. Step-up transformer
C. Isolation transformer with equal voltage
D. Autotransformer operating at unity ratio
Answer: A
Rationale: A transformer that reduces voltage from 480 volts to 120 volts is a
step-down transformer.
5. What is the principal purpose of an equipment grounding conductor?
A. To carry normal neutral current
B. To increase circuit voltage
C. To provide a fault-current path
D. To serve as the grounding electrode
,Answer: C
Rationale: The equipment grounding conductor provides a conductive path for
fault current and helps facilitate operation of overcurrent protective devices
during a fault.
6. What is the primary purpose of the Chicago Electrical Code?
A. To establish minimum requirements for safe electrical installations within its
jurisdiction
B. To establish utility electricity rates
C. To regulate electrical manufacturing nationwide
D. To replace all federal workplace safety regulations
Answer: A
Rationale: The Chicago Electrical Code establishes electrical installation
requirements intended to protect persons and property from hazards associated
with electricity within the jurisdiction.
7. Which reference is the primary technical code reference for the current
Chicago Supervising Electrician examination?
A. 2014 National Electrical Code
B. 2017 National Electrical Code without amendments
C. 2018 Chicago Electrical Code
D. 2023 National Electrical Code only
Answer: C
Rationale: The current Chicago Supervising Electrician examination information
identifies the 2018 Chicago Electrical Code as the principal examination reference.
The Chicago code incorporates Chicago-specific amendments to the NEC.
8. How many questions are included on the Chicago Supervising Electrician
examination?
, A. 100
B. 125
C. 150
D. 175
Answer: C
Rationale: The official Chicago Supervising Electricians study guide states that the
Supervising Electrician examination contains 150 questions with a four-hour time
limit.
9. What score is required to receive a passing result on the Chicago Supervising
Electrician examination?
A. 60
B. 65
C. 70
D. 75
Answer: C
Rationale: The official study guide states that candidates who score 70 or higher
receive a passing notice.
10. What is the primary purpose of an electrical blueprint or plan?
A. To establish the utility company's billing rate
B. To communicate the intended electrical installation
C. To replace all electrical inspections
D. To determine the contractor's insurance premium
Answer: B
Rationale: Electrical drawings communicate the intended locations, circuits,
equipment, wiring, and other installation details so the work can be installed and
coordinated correctly.
Practice Questions and Correct Answers
(Verified Answers) Plus Rationales 2027
Q&A | Instant Download Pdf
Electrical Principles, Safety, and Chicago Electrical Code
1. Which unit is used to express electrical power?
A. Ohm
B. Ampere
C. Watt
D. Coulomb
Answer: C
Rationale: The watt is the unit of electrical power. Power in a DC circuit can be
calculated as P = E × I, where P is watts, E is volts, and I is amperes.
2. A balanced 3-phase load operates at 208 volts line-to-line and draws 30
amperes at unity power factor. Approximately how much apparent power does
the load use?
A. 10.8 kVA
B. 17.3 kVA
C. 24.0 kVA
D. 36.0 kVA
Answer: B
Rationale: For a balanced three-phase system, apparent power is S = √3 × V × I.
Therefore, S = 1.732 × 208 × 30 ≈ 10,804 VA, or about 10.8 kVA. The correct
answer is actually A.
,Correct Answer: A
Rationale: The three-phase apparent-power formula is S = √3 × V × I. Using 208
volts and 30 amperes gives approximately 10.8 kVA.
3. What happens to voltage drop when conductor resistance increases while
circuit current remains constant?
A. Voltage drop decreases
B. Voltage drop increases
C. Voltage drop becomes zero
D. Voltage drop becomes independent of resistance
Answer: B
Rationale: Voltage drop is calculated using E = I × R. If current remains constant,
increasing resistance directly increases the voltage drop.
4. A transformer has 480 volts on its primary and 120 volts on its secondary.
What type of transformer is this?
A. Step-down transformer
B. Step-up transformer
C. Isolation transformer with equal voltage
D. Autotransformer operating at unity ratio
Answer: A
Rationale: A transformer that reduces voltage from 480 volts to 120 volts is a
step-down transformer.
5. What is the principal purpose of an equipment grounding conductor?
A. To carry normal neutral current
B. To increase circuit voltage
C. To provide a fault-current path
D. To serve as the grounding electrode
,Answer: C
Rationale: The equipment grounding conductor provides a conductive path for
fault current and helps facilitate operation of overcurrent protective devices
during a fault.
6. What is the primary purpose of the Chicago Electrical Code?
A. To establish minimum requirements for safe electrical installations within its
jurisdiction
B. To establish utility electricity rates
C. To regulate electrical manufacturing nationwide
D. To replace all federal workplace safety regulations
Answer: A
Rationale: The Chicago Electrical Code establishes electrical installation
requirements intended to protect persons and property from hazards associated
with electricity within the jurisdiction.
7. Which reference is the primary technical code reference for the current
Chicago Supervising Electrician examination?
A. 2014 National Electrical Code
B. 2017 National Electrical Code without amendments
C. 2018 Chicago Electrical Code
D. 2023 National Electrical Code only
Answer: C
Rationale: The current Chicago Supervising Electrician examination information
identifies the 2018 Chicago Electrical Code as the principal examination reference.
The Chicago code incorporates Chicago-specific amendments to the NEC.
8. How many questions are included on the Chicago Supervising Electrician
examination?
, A. 100
B. 125
C. 150
D. 175
Answer: C
Rationale: The official Chicago Supervising Electricians study guide states that the
Supervising Electrician examination contains 150 questions with a four-hour time
limit.
9. What score is required to receive a passing result on the Chicago Supervising
Electrician examination?
A. 60
B. 65
C. 70
D. 75
Answer: C
Rationale: The official study guide states that candidates who score 70 or higher
receive a passing notice.
10. What is the primary purpose of an electrical blueprint or plan?
A. To establish the utility company's billing rate
B. To communicate the intended electrical installation
C. To replace all electrical inspections
D. To determine the contractor's insurance premium
Answer: B
Rationale: Electrical drawings communicate the intended locations, circuits,
equipment, wiring, and other installation details so the work can be installed and
coordinated correctly.
