Colorado Residential Wireman Examination
Questions and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant Download Pdf
Question 1
What is the primary purpose of an equipment grounding conductor
(EGC) in a residential branch circuit?
A. To carry normal load current
B. To increase circuit voltage
C. To provide a low-impedance path for fault current
D. To reduce the resistance of the neutral conductor
Answer: C. To provide a low-impedance path for fault current
Rationale: The equipment grounding conductor normally carries no
current. Its purpose is to provide a low-impedance path back to the
source when a fault occurs, allowing the overcurrent protective device
to operate and disconnect the faulty circuit.
,Question 2
Which conductor is normally connected to the grounded terminal of a
standard 120-volt receptacle?
A. Equipment grounding conductor
B. Ungrounded conductor
C. Grounded conductor
D. Bonding jumper
Answer: C. Grounded conductor
Rationale: The grounded conductor, commonly called the neutral, is
connected to the grounded or silver-colored terminal of a standard
receptacle. The ungrounded conductor connects to the brass-colored
terminal, while the equipment grounding conductor connects to the
green grounding terminal.
Question 3
What is the standard nominal voltage between the ungrounded
conductor and grounded conductor in a typical residential single-phase
circuit?
A. 24 volts
B. 120 volts
,C. 208 volts
D. 480 volts
Answer: B. 120 volts
Rationale: Typical residential branch circuits in the United States
provide approximately 120 volts between an ungrounded conductor and
the grounded conductor. A 240-volt circuit generally uses two
ungrounded conductors with approximately 240 volts between them.
Question 4
Which device is designed to interrupt a circuit automatically when
excessive current flows?
A. Transformer
B. Circuit breaker
C. Receptacle
D. Junction box
Answer: B. Circuit breaker
Rationale: A circuit breaker is an overcurrent protective device. It opens
the circuit when current exceeds its permitted level for a sufficient
period, helping protect conductors and connected equipment from
overheating and damage.
, Question 5
What is the main purpose of a GFCI?
A. Protect against excessive voltage
B. Detect an imbalance between current leaving and returning through
the circuit
C. Increase available circuit current
D. Protect only against short circuits
Answer: B. Detect an imbalance between current leaving and
returning through the circuit
Rationale: A ground-fault circuit interrupter monitors the current
supplied on the circuit and compares it with the current returning. A
difference indicates current may be flowing through an unintended
path, and the GFCI is designed to disconnect the circuit rapidly.
Question 6
Which type of receptacle is commonly required in locations where
electrical shock hazards may be increased by moisture?
Questions and Correct Answers (Verified Answers)
Plus Rationale 2027 Q&A| Instant Download Pdf
Question 1
What is the primary purpose of an equipment grounding conductor
(EGC) in a residential branch circuit?
A. To carry normal load current
B. To increase circuit voltage
C. To provide a low-impedance path for fault current
D. To reduce the resistance of the neutral conductor
Answer: C. To provide a low-impedance path for fault current
Rationale: The equipment grounding conductor normally carries no
current. Its purpose is to provide a low-impedance path back to the
source when a fault occurs, allowing the overcurrent protective device
to operate and disconnect the faulty circuit.
,Question 2
Which conductor is normally connected to the grounded terminal of a
standard 120-volt receptacle?
A. Equipment grounding conductor
B. Ungrounded conductor
C. Grounded conductor
D. Bonding jumper
Answer: C. Grounded conductor
Rationale: The grounded conductor, commonly called the neutral, is
connected to the grounded or silver-colored terminal of a standard
receptacle. The ungrounded conductor connects to the brass-colored
terminal, while the equipment grounding conductor connects to the
green grounding terminal.
Question 3
What is the standard nominal voltage between the ungrounded
conductor and grounded conductor in a typical residential single-phase
circuit?
A. 24 volts
B. 120 volts
,C. 208 volts
D. 480 volts
Answer: B. 120 volts
Rationale: Typical residential branch circuits in the United States
provide approximately 120 volts between an ungrounded conductor and
the grounded conductor. A 240-volt circuit generally uses two
ungrounded conductors with approximately 240 volts between them.
Question 4
Which device is designed to interrupt a circuit automatically when
excessive current flows?
A. Transformer
B. Circuit breaker
C. Receptacle
D. Junction box
Answer: B. Circuit breaker
Rationale: A circuit breaker is an overcurrent protective device. It opens
the circuit when current exceeds its permitted level for a sufficient
period, helping protect conductors and connected equipment from
overheating and damage.
, Question 5
What is the main purpose of a GFCI?
A. Protect against excessive voltage
B. Detect an imbalance between current leaving and returning through
the circuit
C. Increase available circuit current
D. Protect only against short circuits
Answer: B. Detect an imbalance between current leaving and
returning through the circuit
Rationale: A ground-fault circuit interrupter monitors the current
supplied on the circuit and compares it with the current returning. A
difference indicates current may be flowing through an unintended
path, and the GFCI is designed to disconnect the circuit rapidly.
Question 6
Which type of receptacle is commonly required in locations where
electrical shock hazards may be increased by moisture?
