Best Arizona CR-11 Electrical Contractor Exam
Practice Questions And Correct Answers
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Question 1
What is the primary purpose of grounding an electrical system?
A. Increase voltage
B. Prevent shock hazards and stabilize system voltage
C. Reduce conductor size
D. Increase circuit capacity
Answer: B. Prevent shock hazards and stabilize system voltage
Explanation: Grounding provides a low-impedance path for fault current to return to the
source, allowing overcurrent protective devices such as circuit breakers or fuses to operate
quickly. It also helps stabilize the electrical system voltage with respect to earth, reducing
the risk of electric shock, equipment damage, and fire.
NEC Reference: Article 250 – Grounding and Bonding (especially 250.4, General
Requirements for Grounding and Bonding).
Question 2
According to the NEC, what is the minimum size copper conductor permitted for a 20-
amp branch circuit?
A. 14 AWG
B. 12 AWG
C. 10 AWG
D. 8 AWG
,Answer: B. 12 AWG
Explanation: A 20-amp branch circuit requires a minimum of 12 AWG copper conductors.
Using a conductor smaller than 12 AWG on a 20-amp overcurrent device can cause
excessive heating before the breaker trips, creating a fire hazard. The conductor ampacity
must not be less than the rating of the overcurrent protection.
NEC Reference: Article 210.19(A) – Minimum Size Conductors; Article 240.4(D) – Small
Conductors.
Question 3
A Ground-Fault Circuit Interrupter (GFCI) is primarily designed to protect against:
A. Short circuits
B. Overloads
C. Electric shock caused by ground faults
D. High voltage
Answer: C. Electric shock caused by ground faults
Explanation: A GFCI continuously compares the current leaving on the ungrounded (hot)
conductor with the current returning on the grounded (neutral) conductor. If the difference is
approximately 4–6 milliamperes, indicating current is leaking to ground (possibly through a
person), the GFCI opens the circuit in a fraction of a second to reduce the risk of serious
electric shock.
NEC Reference: Article 210.8 – Ground-Fault Circuit-Interrupter Protection for Personnel.
Question 4
What does the NEC define as a continuous load?
A. A load operating for 30 minutes or more
B. A load operating for 1 hour or more
C. A load where the maximum current is expected to continue for 3 hours or more
D. A load operating for 8 hours or more
,Answer: C. A load where the maximum current is expected to continue for 3 hours or
more
Explanation: The NEC defines a continuous load as one where the maximum current is
expected to continue for 3 hours or more. Branch circuits and overcurrent devices serving
continuous loads are generally sized at 125% of the continuous load.
NEC Reference: Article 100 – Definitions (Continuous Load); Article 210.20(A); Article
215.3.
Question 5
Which organization publishes the National Electrical Code (NEC)?
A. OSHA
B. IEEE
C. National Fire Protection Association (NFPA)
D. ANSI
Answer: C. National Fire Protection Association (NFPA)
Explanation: The National Electrical Code is published by the National Fire Protection
Association (NFPA) as NFPA 70. It is revised on a three-year cycle and serves as the
minimum standard for safe electrical installations in the United States.
NEC Reference: NFPA 70 – National Electrical Code.
Question 6
The minimum working clearance in front of 120/240V electrical equipment is
generally:
A. 24 inches
B. 30 inches
C. 36 inches
D. 48 inches
Answer: C. 36 inches
, Explanation: The NEC requires a minimum clear working space of 36 inches in front of
electrical equipment operating at 0–150 volts to ground. This space ensures safe operation,
maintenance, and reduces shock hazards.
NEC Reference: Article 110.26(A)(1) – Working Space Depth.
Question 7
Which conductor is intentionally connected to earth at the service?
A. Hot conductor
B. Grounded (neutral) conductor
C. Equipment grounding conductor
D. Switch leg
Answer: B. Grounded (neutral) conductor
Explanation: The grounded (neutral) conductor is connected to earth at the service
disconnecting means. This establishes a reference point for the electrical system and
stabilizes voltage.
NEC Reference: Article 250.24 – Grounding of Service-Supplied Alternating-Current
Systems.
Question 8
Ohm’s Law is expressed as:
A. P = V × I
B. V = I × R
C. I = P × R
D. R = P ÷ V
Answer: B. V = I × R
Explanation: Ohm’s Law defines the relationship between voltage, current, and resistance.
Voltage equals current multiplied by resistance.
NEC Reference: Fundamental Electrical Theory (no specific NEC article).
Practice Questions And Correct Answers
(Verified Answers) Plus Rationale 2026 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of grounding an electrical system?
A. Increase voltage
B. Prevent shock hazards and stabilize system voltage
C. Reduce conductor size
D. Increase circuit capacity
Answer: B. Prevent shock hazards and stabilize system voltage
Explanation: Grounding provides a low-impedance path for fault current to return to the
source, allowing overcurrent protective devices such as circuit breakers or fuses to operate
quickly. It also helps stabilize the electrical system voltage with respect to earth, reducing
the risk of electric shock, equipment damage, and fire.
NEC Reference: Article 250 – Grounding and Bonding (especially 250.4, General
Requirements for Grounding and Bonding).
Question 2
According to the NEC, what is the minimum size copper conductor permitted for a 20-
amp branch circuit?
A. 14 AWG
B. 12 AWG
C. 10 AWG
D. 8 AWG
,Answer: B. 12 AWG
Explanation: A 20-amp branch circuit requires a minimum of 12 AWG copper conductors.
Using a conductor smaller than 12 AWG on a 20-amp overcurrent device can cause
excessive heating before the breaker trips, creating a fire hazard. The conductor ampacity
must not be less than the rating of the overcurrent protection.
NEC Reference: Article 210.19(A) – Minimum Size Conductors; Article 240.4(D) – Small
Conductors.
Question 3
A Ground-Fault Circuit Interrupter (GFCI) is primarily designed to protect against:
A. Short circuits
B. Overloads
C. Electric shock caused by ground faults
D. High voltage
Answer: C. Electric shock caused by ground faults
Explanation: A GFCI continuously compares the current leaving on the ungrounded (hot)
conductor with the current returning on the grounded (neutral) conductor. If the difference is
approximately 4–6 milliamperes, indicating current is leaking to ground (possibly through a
person), the GFCI opens the circuit in a fraction of a second to reduce the risk of serious
electric shock.
NEC Reference: Article 210.8 – Ground-Fault Circuit-Interrupter Protection for Personnel.
Question 4
What does the NEC define as a continuous load?
A. A load operating for 30 minutes or more
B. A load operating for 1 hour or more
C. A load where the maximum current is expected to continue for 3 hours or more
D. A load operating for 8 hours or more
,Answer: C. A load where the maximum current is expected to continue for 3 hours or
more
Explanation: The NEC defines a continuous load as one where the maximum current is
expected to continue for 3 hours or more. Branch circuits and overcurrent devices serving
continuous loads are generally sized at 125% of the continuous load.
NEC Reference: Article 100 – Definitions (Continuous Load); Article 210.20(A); Article
215.3.
Question 5
Which organization publishes the National Electrical Code (NEC)?
A. OSHA
B. IEEE
C. National Fire Protection Association (NFPA)
D. ANSI
Answer: C. National Fire Protection Association (NFPA)
Explanation: The National Electrical Code is published by the National Fire Protection
Association (NFPA) as NFPA 70. It is revised on a three-year cycle and serves as the
minimum standard for safe electrical installations in the United States.
NEC Reference: NFPA 70 – National Electrical Code.
Question 6
The minimum working clearance in front of 120/240V electrical equipment is
generally:
A. 24 inches
B. 30 inches
C. 36 inches
D. 48 inches
Answer: C. 36 inches
, Explanation: The NEC requires a minimum clear working space of 36 inches in front of
electrical equipment operating at 0–150 volts to ground. This space ensures safe operation,
maintenance, and reduces shock hazards.
NEC Reference: Article 110.26(A)(1) – Working Space Depth.
Question 7
Which conductor is intentionally connected to earth at the service?
A. Hot conductor
B. Grounded (neutral) conductor
C. Equipment grounding conductor
D. Switch leg
Answer: B. Grounded (neutral) conductor
Explanation: The grounded (neutral) conductor is connected to earth at the service
disconnecting means. This establishes a reference point for the electrical system and
stabilizes voltage.
NEC Reference: Article 250.24 – Grounding of Service-Supplied Alternating-Current
Systems.
Question 8
Ohm’s Law is expressed as:
A. P = V × I
B. V = I × R
C. I = P × R
D. R = P ÷ V
Answer: B. V = I × R
Explanation: Ohm’s Law defines the relationship between voltage, current, and resistance.
Voltage equals current multiplied by resistance.
NEC Reference: Fundamental Electrical Theory (no specific NEC article).
