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NATE Certified HVAC Professional (CHP-5) Electrical
and Controls Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION
This comprehensive set of multiple-choice questions is designed for the NATE Certified
HVAC Professional (CHP-5) Electrical and Controls exam, one of five specialized
certification exams for HVAC technicians administered by North American Technician
Excellence (NATE). The exam assesses practical, on-the-job knowledge of electrical
science fundamentals, circuit analysis, HVAC electrical components (including
contactors, relays, thermostats, and motor controls), interpretation of schematics and
wiring diagrams, and systematic troubleshooting techniques using a multimeter.
QUESTION 1
When a free electron leaves the valence orbit of one atom and enters the valence orbit
of another atom, the first atom becomes a:
A. Negative ion
B. Positive ion
C. Neutral atom
D. Magnetic domain
CORRECT ANSWER: B. Positive ion
EXPERT RATIONALE: Losing an electron leaves more protons than electrons, resulting in
a net positive charge. This is the definition of a positive ion.
QUESTION 2
The ability of a material to concentrate magnetic lines of flux is called:
A. Reluctance
B. Permeability
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C. Reactance
D. Hysteresis
CORRECT ANSWER: B. Permeability
EXPERT RATIONALE: Permeability measures how easily a material supports the
formation of a magnetic field; high permeability means it concentrates flux well.
Reluctance is the opposition to magnetic flux.
QUESTION 3
In a simple step-down transformer, if the secondary winding has half as many turns as
the primary, the secondary voltage will be:
A. Double the primary voltage
B. Equal to the primary voltage
C. Half the primary voltage
D. Zero volts
CORRECT ANSWER: C. Half the primary voltage
EXPERT RATIONALE: Transformer voltage ratio is directly proportional to the turns ratio.
Half the turns on the secondary yields half the voltage.
QUESTION 4
A contactor coil that is rated for 24 V AC is accidentally connected to 24 V DC. What will
most likely occur?
A. The coil will operate normally
B. The coil will overheat and burn out
C. The contactor will chatter but hold
D. The coil will produce a stronger magnetic field
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CORRECT ANSWER: B. The coil will overheat and burn out
EXPERT RATIONALE: AC coils rely on inductive reactance to limit current; applying DC
removes that reactance, causing excessive current and heat. The coil will quickly
overheat.
QUESTION 5
A technician measures 120 V across a closed switch that is supposed to be supplying a
load. This reading most likely indicates:
A. The switch is operating normally
B. There is a short circuit in the load
C. The switch contacts are open
D. The load is drawing too much current
CORRECT ANSWER: C. The switch contacts are open
EXPERT RATIONALE: A closed good switch has nearly zero voltage drop; full supply
voltage across the switch means it is open or has a high-resistance contact.
QUESTION 6
Which of the following quantities is defined as the opposition to current flow in an AC
circuit caused by capacitance or inductance?
A. Resistance
B. Impedance
C. Reactance
D. Reluctance
CORRECT ANSWER: C. Reactance
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EXPERT RATIONALE: Reactance is the component of opposition due to inductance or
capacitance. Impedance combines resistance and reactance.
QUESTION 7
A circuit has a 24 V AC source connected to a relay coil with an inductance of 0.2 H and
negligible resistance. What happens to the coil current if the frequency of the source
increases from 60 Hz to 120 Hz?
A. Current increases
B. Current decreases
C. Current remains the same
D. Current becomes zero
CORRECT ANSWER: B. Current decreases
EXPERT RATIONALE: Inductive reactance (XL = 2πfL) increases with frequency, so higher
frequency increases opposition, reducing current.
QUESTION 8
On a ladder diagram, two pushbutton contacts drawn in parallel represent a:
A. Series circuit
B. OR logic function
C. AND logic function
D. Normally closed interlock
CORRECT ANSWER: B. OR logic function
EXPERT RATIONALE: Parallel contacts provide an alternative path; if either contact
closes, the circuit completes, which is logical OR.
NATE Certified HVAC Professional (CHP-5) Electrical
and Controls Exam | Latest Verified Questions and
Detailed Answers
OVERVIEW DESCRIPTION
This comprehensive set of multiple-choice questions is designed for the NATE Certified
HVAC Professional (CHP-5) Electrical and Controls exam, one of five specialized
certification exams for HVAC technicians administered by North American Technician
Excellence (NATE). The exam assesses practical, on-the-job knowledge of electrical
science fundamentals, circuit analysis, HVAC electrical components (including
contactors, relays, thermostats, and motor controls), interpretation of schematics and
wiring diagrams, and systematic troubleshooting techniques using a multimeter.
QUESTION 1
When a free electron leaves the valence orbit of one atom and enters the valence orbit
of another atom, the first atom becomes a:
A. Negative ion
B. Positive ion
C. Neutral atom
D. Magnetic domain
CORRECT ANSWER: B. Positive ion
EXPERT RATIONALE: Losing an electron leaves more protons than electrons, resulting in
a net positive charge. This is the definition of a positive ion.
QUESTION 2
The ability of a material to concentrate magnetic lines of flux is called:
A. Reluctance
B. Permeability
,2|Page
C. Reactance
D. Hysteresis
CORRECT ANSWER: B. Permeability
EXPERT RATIONALE: Permeability measures how easily a material supports the
formation of a magnetic field; high permeability means it concentrates flux well.
Reluctance is the opposition to magnetic flux.
QUESTION 3
In a simple step-down transformer, if the secondary winding has half as many turns as
the primary, the secondary voltage will be:
A. Double the primary voltage
B. Equal to the primary voltage
C. Half the primary voltage
D. Zero volts
CORRECT ANSWER: C. Half the primary voltage
EXPERT RATIONALE: Transformer voltage ratio is directly proportional to the turns ratio.
Half the turns on the secondary yields half the voltage.
QUESTION 4
A contactor coil that is rated for 24 V AC is accidentally connected to 24 V DC. What will
most likely occur?
A. The coil will operate normally
B. The coil will overheat and burn out
C. The contactor will chatter but hold
D. The coil will produce a stronger magnetic field
,3|Page
CORRECT ANSWER: B. The coil will overheat and burn out
EXPERT RATIONALE: AC coils rely on inductive reactance to limit current; applying DC
removes that reactance, causing excessive current and heat. The coil will quickly
overheat.
QUESTION 5
A technician measures 120 V across a closed switch that is supposed to be supplying a
load. This reading most likely indicates:
A. The switch is operating normally
B. There is a short circuit in the load
C. The switch contacts are open
D. The load is drawing too much current
CORRECT ANSWER: C. The switch contacts are open
EXPERT RATIONALE: A closed good switch has nearly zero voltage drop; full supply
voltage across the switch means it is open or has a high-resistance contact.
QUESTION 6
Which of the following quantities is defined as the opposition to current flow in an AC
circuit caused by capacitance or inductance?
A. Resistance
B. Impedance
C. Reactance
D. Reluctance
CORRECT ANSWER: C. Reactance
, 4|Page
EXPERT RATIONALE: Reactance is the component of opposition due to inductance or
capacitance. Impedance combines resistance and reactance.
QUESTION 7
A circuit has a 24 V AC source connected to a relay coil with an inductance of 0.2 H and
negligible resistance. What happens to the coil current if the frequency of the source
increases from 60 Hz to 120 Hz?
A. Current increases
B. Current decreases
C. Current remains the same
D. Current becomes zero
CORRECT ANSWER: B. Current decreases
EXPERT RATIONALE: Inductive reactance (XL = 2πfL) increases with frequency, so higher
frequency increases opposition, reducing current.
QUESTION 8
On a ladder diagram, two pushbutton contacts drawn in parallel represent a:
A. Series circuit
B. OR logic function
C. AND logic function
D. Normally closed interlock
CORRECT ANSWER: B. OR logic function
EXPERT RATIONALE: Parallel contacts provide an alternative path; if either contact
closes, the circuit completes, which is logical OR.
