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100+ Free C-38 Refrigeration Practice Questions

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Key Facts: C-38 Refrigeration Exam

3.5 Hours

Time Limit

CSLB

4 Years

Experience Required

CSLB

$450

Exam Fee

CSLB

18%

Planning & Estimating

CSLB Outline

26%

System Installation

CSLB Outline

The CSLB C-38 Refrigeration exam is a 3.5-hour, computer-delivered test administered by PSI. Candidates must have 4 years of journey-level experience to qualify and pay a $450 application fee. The exam covers Planning and Estimating (18%), System Installation (26%), Repair (22%), Maintenance (18%), and Safety (16%).

Sample C-38 Refrigeration Practice Questions

Try these sample questions to test your C-38 Refrigeration exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A walk-in cooler load calculation requires calculating sensible heat gain from outdoor ventilation air. If 200 CFM of outdoor air at 95 degrees F dry-bulb enters a walk-in cooler maintained at 35 degrees F, what is the sensible heat load in BTU/hr?
A.12,960 BTU/hr sensible heat load.
B.15,480 BTU/hr sensible heat load.
C.10,800 BTU/hr sensible heat load.
D.18,200 BTU/hr sensible heat load.
Explanation: Sensible heat load from ventilation air is calculated using the standard formula Q = 1.08 x CFM x Delta T. Substituting the design values gives Q = 1.08 x 200 CFM x (95 - 35) = 1.08 x 200 x 60 = 12,960 BTU/hr. Accurate infiltration load estimation is essential to size refrigeration compressors without under-cooling during peak ambient conditions.
2A commercial freezer wall has an overall heat transfer coefficient (U-factor) of 0.035 BTU/hr-sq ft-degree F and a surface area of 400 sq ft. If the ambient design temperature is 90 degrees F and the freezer interior is -10 degrees F, what is the wall heat transmission load?
A.1,120 BTU/hr total wall transmission heat load.
B.1,400 BTU/hr total wall transmission heat load.
C.1,680 BTU/hr total wall transmission heat load.
D.2,100 BTU/hr total wall transmission heat load.
Explanation: Wall transmission heat gain is calculated using Q = U x A x Delta T. The temperature difference is Delta T = 90 - (-10) = 100 degrees F. Thus, Q = 0.035 x 400 sq ft x 100 degrees F = 1,400 BTU/hr. Estimating heat gain across insulated envelope surfaces is critical when planning equipment runtime and insulation thickness for low-temperature applications.
3A refrigeration contractor must estimate the product load to cool 2,000 lbs of fresh beef from 65 degrees F down to 35 degrees F over a 24-hour pull-down period. Given the specific heat above freezing is 0.75 BTU/lb-degree F, what is the required hourly product cooling load?
A.1,250 BTU/hr required hourly cooling load.
B.1,500 BTU/hr required hourly cooling load.
C.1,875 BTU/hr required hourly cooling load.
D.2,250 BTU/hr required hourly cooling load.
Explanation: Product heat removal above freezing is calculated with Q = weight x specific heat x Delta T. Here, Q = 2,000 lbs x 0.75 BTU/lb-degree F x (65 - 35) = 45,000 BTU total. Dividing by 24 hours yields 1,875 BTU/hr. Properly sizing equipment for product pull-down prevents food spoilage and compressor short-cycling.
4When estimating compressor operating conditions for an R-404A low-temperature system, suction pressure is 15.3 psig and discharge pressure is 235.3 psig. What is the absolute compression ratio of the system?
A.15.38:1 absolute compressor pressure ratio.
B.12.50:1 absolute compressor pressure ratio.
C.10.25:1 absolute compressor pressure ratio.
D.8.33:1 absolute compressor pressure ratio.
Explanation: Compression ratio is the absolute discharge pressure divided by the absolute suction pressure. Converting to psia: Suction = 15.3 + 14.7 = 30.0 psia; Discharge = 235.3 + 14.7 = 250.0 psia. The compression ratio is 250.0 / 30.0 = 8.33:1. High compression ratios reduce volumetric efficiency and require multi-stage compression or desuperheating solutions.
5According to standard commercial refrigeration piping guidelines, what minimum suction line refrigerant velocity must be maintained in vertical risers during minimum system load capacity to ensure proper oil return to the compressor?
A.1,500 feet per minute minimum line velocity.
B.2,500 feet per minute minimum line velocity.
C.3,500 feet per minute minimum line velocity.
D.4,500 feet per minute minimum line velocity.
Explanation: Standard refrigeration engineering practices specify a minimum velocity of 1,500 feet per minute (FPM) in vertical suction risers under minimum load conditions to entrain and drag compressor oil upward back to the crankcase. In horizontal lines, 500 to 750 FPM is acceptable. Maintaining minimum velocity prevents oil logging in evaporators and oil starvation in compressors.
6In commercial refrigeration system planning, what is the maximum recommended total equivalent pressure drop in liquid lines, expressed in terms of saturation temperature change?
A.0.5 degree Fahrenheit saturation drop.
B.1 to 2 degrees Fahrenheit saturation drop.
C.5 to 6 degrees Fahrenheit saturation drop.
D.8 to 10 degrees Fahrenheit saturation drop.
Explanation: Liquid lines are generally sized for a pressure drop corresponding to a 1 to 2 degrees F change in saturation temperature (typically 3 to 5 psi for common halogenated refrigerants). Excessive pressure drop in liquid lines causes liquid refrigerant to flash into vapor before reaching the expansion valve, reducing valve capacity and system efficiency.
7When planning the electrical branch circuit wire size for a hermetic motor-compressor with a rated-load current (RLC) of 24 amperes, what minimum conductor ampacity must be specified under California Electrical Code standards?
A.24 amperes minimum conductor ampacity.
B.27 amperes minimum conductor ampacity.
C.30 amperes minimum conductor ampacity.
D.36 amperes minimum conductor ampacity.
Explanation: Per California Electrical Code (CEC Article 440), branch circuit conductors supplying a single motor-compressor must have an ampacity of at least 125% of the rated-load current (RLC) or branch-circuit selection current (BCSC), whichever is greater. Calculation: 24 A x 1.25 = 30 amperes. Sizing conductors at 125% accounts for continuous motor operation and thermal heating.
8Under California Electrical Code rules, what maximum standard percentage rating of rated-load current is initially permitted for the continuous overcurrent protective device (OCPD) on a motor-compressor branch circuit?
A.115 percent of rated load current value.
B.125 percent of rated load current value.
C.150 percent of rated load current value.
D.175 percent of rated load current value.
Explanation: CEC Article 440 specifies that the motor-compressor branch-circuit short-circuit and ground-fault protective device shall not exceed 175% of the motor-compressor rated-load current (or BCSC). If 175% cannot carry the starting current, it may be increased to a maximum of 225%. Proper OCPD sizing prevents nuisance tripping during locked-rotor motor startup while protecting circuit conductors.
9According to California Mechanical Code (CMC Chapter 11), what formula determines the required mechanical emergency exhaust ventilation rate Q in CFM for a machinery room containing a total refrigerant charge M of 400 lbs?
A.2,000 CFM required exhaust ventilation rate.
B.4,000 CFM required exhaust ventilation rate.
C.6,000 CFM required exhaust ventilation rate.
D.8,000 CFM required exhaust ventilation rate.
Explanation: Per California Mechanical Code (CMC 1105.0) and ASHRAE 15, the emergency mechanical ventilation rate is determined by Q = 100 x sqrt(M), where M is the refrigerant charge in pounds. Calculation: Q = 100 x sqrt(400) = 100 x 20 = 2,000 CFM. Emergency ventilation prevents toxic buildup or oxygen displacement in machinery rooms during major leaks.
10When estimating piping materials for a commercial refrigeration machinery room, which copper pipe classification is required by California Mechanical Code Chapter 11 for exposed suction lines?
A.Type M seamless drawn hard copper tubing.
B.Type L seamless drawn hard copper tubing.
C.Type DWV seamless drawn hard copper pipe.
D.Class 125 threaded galvanized steel pipe.
Explanation: CMC Chapter 11 (Section 1110.0) mandates that refrigerant copper piping used in field installations shall be seamless copper tube Type K or L complying with ASTM B88 or ASTM B280. Type M and DWV tubing have thinner wall dimensions and are explicitly prohibited for pressure refrigerant lines to prevent mechanical failure and rupture under vibration.

About the C-38 Refrigeration Exam

The C-38 exam evaluates candidates on planning, installing, repairing, and maintaining refrigeration systems according to California codes and safety standards.

Assessment

Question count not published by the exam provider

Time Limit

3.5 hours

Passing Score

Disclosed at test site

Exam Fee

$450 application fee (California Contractors State License Board (CSLB))

C-38 Refrigeration Exam Content Outline

18%

Planning and Estimating

Reviewing blueprints, selecting equipment, performing load calculations, and estimating material/labor costs.

26%

Refrigeration System Installation

Installing piping, electrical components, compressors, evaporators, condensers, and controls.

22%

Refrigeration System Repair

Troubleshooting electrical/mechanical issues, detecting leaks, and replacing defective system components.

18%

Refrigeration System Maintenance

Performing preventative maintenance, cleaning coils, checking refrigerant charge, and validating controls.

16%

Safety

Applying OSHA regulations, safe refrigerant handling (EPA 608), personal protective equipment (PPE), and hazard communication.

How to Pass the C-38 Refrigeration Exam

What You Need to Know

  • Passing score: Disclosed at test site
  • Assessment: Question count not published by the exam provider
  • Time limit: 3.5 hours
  • Exam fee: $450 application fee

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

C-38 Refrigeration Study Tips from Top Performers

1Master the pressure-enthalpy (P-H) charts and understand superheat and subcooling measurements.
2Review the California Mechanical Code (CMC) specifically regarding refrigeration piping and equipment.
3Understand electrical schematics and basic troubleshooting for controls and motors.
4Refresh your knowledge of Cal/OSHA regulations regarding confined spaces and high-pressure gases.
5Familiarize yourself with ASHRAE 15 and 34 safety standards for various refrigerants.

Frequently Asked Questions

What is required to take the CSLB C-38 exam?

You need at least four years of qualifying journey-level experience within the last ten years, along with a completed application and the $450 fee.

How long is the C-38 Refrigeration exam?

The examination is computer-administered and you are given a maximum of 3.5 hours to complete it.

What topics are heavily tested on the exam?

Refrigeration System Installation is the largest section at 26%, followed closely by Repair at 22%.

Do I need to know EPA Section 608 rules?

Yes, safe handling, recovery, and regulations related to EPA Section 608 are a critical component of the Safety and Maintenance sections.

Are specific code books tested?

Questions are based on the California Mechanical Code, California Electrical Code, California Building Code, and Title 8 (Cal/OSHA) Safety Orders.