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100+ Free NV C-21B Air Conditioning Practice Questions

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2026 Statistics

Key Facts: NV C-21B Air Conditioning Exam

60 Q

Official Exam Questions

PSI Nevada Contractor CIB updated 3/25/2026

70%

Passing Score

PSI Nevada Contractor CIB updated 3/25/2026

2 hours

Time Allowed

PSI Nevada Contractor CIB updated 3/25/2026

USD 95

PSI Exam Fee (one portion)

PSI Nevada Contractor CIB updated 3/25/2026

Open Book

Book Policy

PSI Nevada Contractor CIB updated 3/25/2026

Nevada C-21B Air Conditioning Contractor Examination is the official NSCB/PSI open book exam: 60 questions, 70% (42 of 60 points), 2 hours, USD 95 (bulletin 270, updated 3/25/2026). Official delivery: English and Spanish.

Sample NV C-21B Air Conditioning Practice Questions

Try these sample questions to test your NV C-21B Air Conditioning exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1Under UMC 2018 Section 310, a horizontal condensate waste pipe from a cooling coil shall have a slope of not less than:
A.1/8 inch per foot (1 percent) toward the point of disposal
B.1/2 inch per foot toward the air handler
C.Level, provided the pipe is 1 inch or larger
D.1/4 inch per foot toward the refrigerant suction line
Explanation: UMC 2018 310.1 requires condensate waste piping to slope not less than 1/8 inch per foot (1 percent) and to be of approved corrosion-resistant material. The table capacities in 310.3 assume that same 1/8-inch-per-foot pitch with the pipe running about three-quarters full. A flat or reverse-pitched drain holds water, grows algae, and overflows the pan.
2Where overflow from a cooling-coil drain pan would damage the building, UMC 2018 requires which additional protection?
A.A larger primary drain only, with no secondary device
B.A plugged overflow opening so the pan can hold more water
C.A hose from the pan to the roof scupper
D.A secondary drain, an auxiliary pan with its own drain, or a water-level device that shuts the equipment off
Explanation: UMC 2018 310.2 requires overflow protection whenever a clogged primary drain would damage the structure or finishes. Acceptable methods are an auxiliary watertight pan with a separate drain, a secondary drain connection above the primary outlet, or a listed water-level detection device that de-energizes the equipment. Nevada rooftop and attic coils routinely need one of those three.
3Per UMC 2018 Table 310.3, what is the minimum condensate waste-pipe diameter for a single air-cooling coil of 15 tons, assuming the equipment outlet is not larger?
A.1/2 inch
B.2 inches
C.1-1/4 inches
D.3/4 inch
Explanation: Table 310.3 sizes condensate waste by tons of refrigeration. The first row, up to 20 tons, is 3/4 inch. Fifteen tons falls in that row. The pipe still may not be smaller than the equipment outlet, and it must keep the 1/8-inch-per-foot slope used to develop the table.
4A Las Vegas packaged rooftop unit is rated 36 tons of refrigeration. Using UMC 2018 Table 310.3 and assuming the factory outlet is not larger, the minimum condensate waste-pipe size is:
A.1 inch
B.3/4 inch
C.1-1/2 inches
D.2 inches
Explanation: Thirty-six tons is in the 21–40 ton row of Table 310.3, which requires a 1-inch condensate waste pipe. The 3/4-inch row stops at 20 tons. If several units dump into one drain, size the common pipe for the combined tonnage, still at 1/8 inch per foot.
5Where cooling-coil condensate is discharged into the building drainage system, UMC 2018 requires the connection to be made:
A.With a direct sanitary tee into a soil stack
B.By pumping the water into a potable-water hose bibb
C.By an indirect waste pipe through an air gap or air break to an approved receptor
D.By tying the drain into a Type B vent cleanout
Explanation: UMC 2018 310.5 (and the matching UPC condensate rules) require an indirect connection so sewage cannot siphon back into the drain pan or evaporative-cooler sump. An air gap or air break to a floor sink, hub drain, or other approved receptor is the field method. A direct sanitary connection is a cross-connection.
6New ACR copper refrigerant piping shall be pressure-tested for leaks with which test medium?
A.Compressed oxygen from a cutting-torch cylinder
B.The system refrigerant, introduced until the gauges reach 400 psig
C.Shop compressed air taken from an oiled contractor compressor
D.Dry nitrogen or another inert gas, regulated to a safe test pressure
Explanation: UMC 2018 Chapter 11 requires an inert-gas pressure test of refrigerant piping before charging. Dry nitrogen with a pressure regulator is the standard medium. Oxygen supports combustion and can explode residual oil in the pipe. Oiled shop air contaminates the circuit, and liquid refrigerant is not a pressure-test gas.
7On a split-system air conditioner, the refrigerant suction (vapor) line shall be insulated so that:
A.The insulation and its vapor retarder stay continuous on the outside of the pipe, limiting heat gain and surface condensation
B.Only the liquid line is covered, because suction gas is already cold
C.The insulation is applied under the copper so the pipe can reject heat
D.No insulation is required on any outdoor line set in Nevada
Explanation: The suction line runs below ambient dew point, so it both gains unwanted heat and sweats. Closed-cell elastomeric insulation with a continuous outer vapor retarder is the usual product. Insulation belongs on the outside of the tube; seams and hanger penetrations must be sealed. Nevada's dry climate reduces but does not eliminate condensation on a 40°F suction line.
8Which insulation is the usual factory covering for refrigerant suction and chilled-water piping in the C-21B temperature range?
A.Closed-cell elastomeric (flexible foam) pipe insulation
B.Unfaced open-cell fiberglass wrap with no jacket
C.Mineral-wool batt stuffed around the tube
D.Expanded polystyrene bead board taped on one side
Explanation: Closed-cell elastomeric foam is both the thermal insulation and the vapor retarder, which is why it is preferred on suction lines and chilled water up to about 220°F. Open-cell or unfaced fibrous products let moisture reach the cold copper and lose R-value. UMC energy tables still apply; the product also has to be listed for the pipe temperature.
9Duct or pipe insulation installed outdoors and exposed to weather must be protected by:
A.An extra layer of unfaced fiberglass only
B.A weather jacket or listed outdoor coating that sheds rain and ultraviolet light
C.Cloth duct tape wrapped in a spiral
D.No covering, because Nevada rainfall is low
Explanation: UMC energy and installation rules require outdoor insulation to be shielded from sun, wind, and rain. Aluminum or sheet-metal jacketing, or a listed outdoor mastic/coating, is the usual protection. Low desert rainfall does not stop UV from destroying foam or ASJ. Wet insulation loses R-value and can load a hanger until it fails.
10Factory-made flexible air ducts shall be supported at the manufacturer's intervals, but not farther apart than which spacing, with sag not more than 1/2 inch per foot between supports?
A.2 feet
B.Supports are not required if the duct is stretched tight
C.10 feet
D.4 feet
Explanation: UMC Chapter 6 and the SMACNA flexible-duct rules used with it require supports at the listing/manufacturer interval, not to exceed 4 feet, and limit sag to 1/2 inch per foot. Excess sag kinks the core, adds friction, and starves the register. A metal collar or listed strap that does not crimp the liner is the hanger, not a wire that cuts the jacket.

About the NV C-21B Air Conditioning Exam

The Nevada C-21B Air Conditioning Contractor Examination is the official Nevada State Contractors Board trade examination administered by PSI Services LLC. The official exam has 60 scored questions. Passing is 70% (42 of 60 points) in 2 hours. The examination is open book. Uniform Mechanical Code, 2018 and NFPA 54, 2012 (allowed in center). PSI lists USD 95 for one examination portion and USD 140 if taken with CMS; otherwise USD 95 per trade exam (Candidate Information Bulletin 270, updated 3/25/2026). NSCB requires a separate CMS examination for most new applicants, plus a USD 300 application fee and a USD 600 biennial license fee. PSI also offers this examination in Spanish; this bank is an English-language MCQ study adaptation, not an official translation. It does not replace required trade experience, board approval, fingerprints, bonding, or the official examination.

Assessment

Open Book computer-based multiple-choice. Uniform Mechanical Code, 2018 and NFPA 54, 2012 (allowed in center)

Time Limit

2 hours

Passing Score

70% (42 of 60 points)

Exam Fee

USD 95 (PSI Services LLC (for the Nevada State Contractors Board))

NV C-21B Air Conditioning Exam Content Outline

7%

Piping

Piping (4 items)

2%

Insulation

Insulation (1 items)

5%

Hangers and Supports

Hangers and Supports (3 items)

2%

Sound, Vibration and Seismic Control

Sound, Vibration and Seismic Control (1 items)

5%

Heating and Cooling Principles

Heating and Cooling Principles (3 items)

7%

Refrigerants and Refrigeration

Refrigerants and Refrigeration (4 items)

10%

Load Calculations

Load Calculations (6 items)

2%

Testing, Adjusting and Balancing

Testing, Adjusting and Balancing (1 items)

5%

Controls

Controls (3 items)

7%

A/C and Heat Pump Equipment

A/C and Heat Pump Equipment (4 items)

7%

Furnaces and Heaters

Furnaces and Heaters (4 items)

5%

Chimneys, Flues and Vents

Chimneys, Flues and Vents (3 items)

3%

Combustion Air

Combustion Air (2 items)

13%

Fuel Systems

Fuel Systems (8 items)

10%

Ducts

Ducts (6 items)

5%

Evaporative Cooling

Evaporative Cooling (3 items)

7%

Safety

Safety (4 items)

How to Pass the NV C-21B Air Conditioning Exam

What You Need to Know

  • Passing score: 70% (42 of 60 points)
  • Assessment: Open Book computer-based multiple-choice. Uniform Mechanical Code, 2018 and NFPA 54, 2012 (allowed in center)
  • Time limit: 2 hours
  • Exam fee: USD 95

Keys to Passing

  • Work through all 100 available questions
  • Review every answer and explanation
  • Track weak areas and revisit them
  • Use our AI tutor for tough concepts

NV C-21B Air Conditioning Study Tips from Top Performers

1Distribute study time to the official bulletin 270 content outline (updated 3/25/2026)
2Use only the PSI-listed references; temporary tabs such as Post-it notes are prohibited
3Confirm NSCB experience documentation before scheduling with PSI
4This bank is an English-language MCQ study aid, not an official PSI form

Frequently Asked Questions

How many questions are on the Nevada C-21B Air Conditioning Contractor Examination?

The official PSI examination has 60 scored questions. Passing is 70% (42 of 60 points) within 2 hours (Candidate Information Bulletin 270, updated 3/25/2026).

How much does the NV C-21B exam cost?

PSI lists USD 95 for one examination portion. Two portions cost USD 140 only if the second portion is CMS. NSCB charges a separate USD 300 application fee and USD 600 biennial license fee.

Is the NV C-21B exam open book?

Yes. PSI lists this examination as open book. Uniform Mechanical Code, 2018 and NFPA 54, 2012 (allowed in center)

Do I still need the CMS examination?

CMS is the required Nevada business-and-law examination. Most new applicants must pass CMS and a trade examination for the requested classification. In most cases you will not retake an exam if you have actively served as a qualified employee in the same classification within the last four years.