NEVADA (NV) C-21B AIR CONDITIONING CONTRACTOR PRACTICE TEST EXAM QUESTIONS
AND CORRECT ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES 2026 Q&A |LATEST EXAM
UPDATE 2026/2027..
Core Domains
Thermodynamics and Psychrometrics
HVAC System Design and Load Calculation
Nevada State Contractor Regulations and Business Management
Safety, OSHA Standards, and Environmental Compliance
Electrical Controls and Wiring Diagrams
Air Distribution and Ductwork Design
Refrigeration Systems and Piping
Troubleshooting and System Diagnostics
Introduction
The purpose of this examination is to evaluate the technical competence, regulatory knowledge, and
professional readiness of candidates seeking licensure as a C-21B Air Conditioning Contractor in the
State of Nevada. The assessment covers essential skills and knowledge required for the design,
installation, maintenance, and repair of residential, commercial, and industrial HVAC systems. Utilizing a
rigorous combination of multiple-choice and scenario-based questions, the exam measures the
candidate's ability to interpret technical data, apply mechanical and electrical theory, and adhere to
relevant building codes and safety regulations. Special emphasis is placed on real-world application,
technical problem-solving, and sound decision-making in the field.
What is the standard design superheat range for a fixed orifice metering device system operating
under normal load conditions?
,A. 2 to 4 degrees Fahrenheit
B. 5 to 8 degrees Fahrenheit
C. 8 to 12 degrees Fahrenheit
D. 🟢 10 to 14 degrees Fahrenheit
🔴 RATIONALE: Fixed orifice systems rely on evaporator superheat to regulate refrigerant feed,
and a target superheat of 10 to 14 degrees Fahrenheit is standard for maintaining efficient
compressor operation without liquid floodback.
Which Nevada Revised Statute chapter primarily governs contractor licensing requirements,
classifications, and disciplinary actions?
A. Chapter 618
B. 🟢 Chapter 624
C. Chapter 446
D. Chapter 701
🔴 RATIONALE: NRS Chapter 624 is the foundational statute establishing the Nevada State
Contractors Board and outlining all licensing regulations and enforcement procedures for
contractors.
When calculating residential cooling loads using ACCA Manual J, what is the default interior design
relative humidity condition?
A. 30 percent
B. 🟢 50 percent
C. 65 percent
D. 75 percent
🔴 RATIONALE: ACCA Manual J specifies a standard indoor design condition of 75 degrees
Fahrenheit and 50 percent relative humidity for summer cooling load calculations.
,A three-phase compressor draws 42 amperes on L1, 41 amperes on L2, and 65 amperes on L3.
What is the most immediate conclusion?
A. The compressor is operating at peak design efficiency.
B. The system is experiencing a balanced high-load condition.
C. 🟢 L3 is heavily overloaded, indicating an electrical fault or phase imbalance.
D. The ambient temperature is too low for proper operation.
🔴 RATIONALE: A significant current imbalance exceeding 10 percent on one phase indicates an
electrical supply issue, winding fault, or severe voltage asymmetry.
What is the minimum required clearance in front of a 480-volt electrical control panel according to
the National Electrical Code?
A. 24 inches
B. 30 inches
C. 🟢 36 inches
D. 48 inches
🔴 RATIONALE: The National Electrical Code mandates a minimum working clearance depth of
36 inches in front of electrical equipment operating at 151 to 600 volts to ensure technician safety.
Which psychrometric property represents the total heat content of air, including both sensible and
latent heat?
A. Dry-bulb temperature
B. Wet-bulb temperature
C. Dew point
D. 🟢 Enthalpy
🔴 RATIONALE: Enthalpy measures the total heat energy in an air-vapor mixture per pound of dry
air, accounting for both sensible and latent heat components.
, Under Nevada law, what is the maximum amount a contractor can require as a down payment on a
residential construction or repair contract before work begins?
A. 10 percent of the total price or 1000 dollars, whichever is less
B. 🟢 10 percent of the total price or 1000 dollars, whichever is greater
C. 20 percent of the total price or 2500 dollars, whichever is less
D. 50 percent of the total price regardless of project cost
🔴 RATIONALE: Nevada licensing regulations restrict the down payment on residential contracts
to 10 percent of the aggregate contract price or 1000 dollars, whichever is lesser.
What is the primary purpose of an economizer cycle in a commercial rooftop unit?
A. To increase compressor capacity during peak summer days
B. 🟢 To utilize outside air for cooling when ambient conditions are favorable
C. To reduce the electrical resistance of the evaporator coil
D. To eliminate the need for an exhaust fan
🔴 RATIONALE: An economizer reduces mechanical cooling energy consumption by introducing
cool outdoor air directly into the conditioned space when ambient temperatures and humidity
permit.
What safety device must be installed on a gas-fired duct furnace when the heating unit is located
upstream of an air conditioning cooling coil?
A. A high-voltage lockout relay
B. 🟢 A condensate overflow switch linked to the gas valve
C. A motorized fresh air damper
D. A secondary pressure relief valve
🔴 RATIONALE: Placing a gas furnace upstream of a cooling coil risks condensate dripping into
the heat exchanger or causing rust; code requires specific interlocking and drainage protection.
AND CORRECT ANSWERS (VERIFIED ANSWERS) PLUS RATIONALES 2026 Q&A |LATEST EXAM
UPDATE 2026/2027..
Core Domains
Thermodynamics and Psychrometrics
HVAC System Design and Load Calculation
Nevada State Contractor Regulations and Business Management
Safety, OSHA Standards, and Environmental Compliance
Electrical Controls and Wiring Diagrams
Air Distribution and Ductwork Design
Refrigeration Systems and Piping
Troubleshooting and System Diagnostics
Introduction
The purpose of this examination is to evaluate the technical competence, regulatory knowledge, and
professional readiness of candidates seeking licensure as a C-21B Air Conditioning Contractor in the
State of Nevada. The assessment covers essential skills and knowledge required for the design,
installation, maintenance, and repair of residential, commercial, and industrial HVAC systems. Utilizing a
rigorous combination of multiple-choice and scenario-based questions, the exam measures the
candidate's ability to interpret technical data, apply mechanical and electrical theory, and adhere to
relevant building codes and safety regulations. Special emphasis is placed on real-world application,
technical problem-solving, and sound decision-making in the field.
What is the standard design superheat range for a fixed orifice metering device system operating
under normal load conditions?
,A. 2 to 4 degrees Fahrenheit
B. 5 to 8 degrees Fahrenheit
C. 8 to 12 degrees Fahrenheit
D. 🟢 10 to 14 degrees Fahrenheit
🔴 RATIONALE: Fixed orifice systems rely on evaporator superheat to regulate refrigerant feed,
and a target superheat of 10 to 14 degrees Fahrenheit is standard for maintaining efficient
compressor operation without liquid floodback.
Which Nevada Revised Statute chapter primarily governs contractor licensing requirements,
classifications, and disciplinary actions?
A. Chapter 618
B. 🟢 Chapter 624
C. Chapter 446
D. Chapter 701
🔴 RATIONALE: NRS Chapter 624 is the foundational statute establishing the Nevada State
Contractors Board and outlining all licensing regulations and enforcement procedures for
contractors.
When calculating residential cooling loads using ACCA Manual J, what is the default interior design
relative humidity condition?
A. 30 percent
B. 🟢 50 percent
C. 65 percent
D. 75 percent
🔴 RATIONALE: ACCA Manual J specifies a standard indoor design condition of 75 degrees
Fahrenheit and 50 percent relative humidity for summer cooling load calculations.
,A three-phase compressor draws 42 amperes on L1, 41 amperes on L2, and 65 amperes on L3.
What is the most immediate conclusion?
A. The compressor is operating at peak design efficiency.
B. The system is experiencing a balanced high-load condition.
C. 🟢 L3 is heavily overloaded, indicating an electrical fault or phase imbalance.
D. The ambient temperature is too low for proper operation.
🔴 RATIONALE: A significant current imbalance exceeding 10 percent on one phase indicates an
electrical supply issue, winding fault, or severe voltage asymmetry.
What is the minimum required clearance in front of a 480-volt electrical control panel according to
the National Electrical Code?
A. 24 inches
B. 30 inches
C. 🟢 36 inches
D. 48 inches
🔴 RATIONALE: The National Electrical Code mandates a minimum working clearance depth of
36 inches in front of electrical equipment operating at 151 to 600 volts to ensure technician safety.
Which psychrometric property represents the total heat content of air, including both sensible and
latent heat?
A. Dry-bulb temperature
B. Wet-bulb temperature
C. Dew point
D. 🟢 Enthalpy
🔴 RATIONALE: Enthalpy measures the total heat energy in an air-vapor mixture per pound of dry
air, accounting for both sensible and latent heat components.
, Under Nevada law, what is the maximum amount a contractor can require as a down payment on a
residential construction or repair contract before work begins?
A. 10 percent of the total price or 1000 dollars, whichever is less
B. 🟢 10 percent of the total price or 1000 dollars, whichever is greater
C. 20 percent of the total price or 2500 dollars, whichever is less
D. 50 percent of the total price regardless of project cost
🔴 RATIONALE: Nevada licensing regulations restrict the down payment on residential contracts
to 10 percent of the aggregate contract price or 1000 dollars, whichever is lesser.
What is the primary purpose of an economizer cycle in a commercial rooftop unit?
A. To increase compressor capacity during peak summer days
B. 🟢 To utilize outside air for cooling when ambient conditions are favorable
C. To reduce the electrical resistance of the evaporator coil
D. To eliminate the need for an exhaust fan
🔴 RATIONALE: An economizer reduces mechanical cooling energy consumption by introducing
cool outdoor air directly into the conditioned space when ambient temperatures and humidity
permit.
What safety device must be installed on a gas-fired duct furnace when the heating unit is located
upstream of an air conditioning cooling coil?
A. A high-voltage lockout relay
B. 🟢 A condensate overflow switch linked to the gas valve
C. A motorized fresh air damper
D. A secondary pressure relief valve
🔴 RATIONALE: Placing a gas furnace upstream of a cooling coil risks condensate dripping into
the heat exchanger or causing rust; code requires specific interlocking and drainage protection.
