Safety — California C-20 Practice Questions

46 questions · 20% of the C-20 HVAC Trade exam

Worked questions

1. A machinery-room refrigerant alarm activates. What is the proper immediate action?

AEnter by smell
Evacuate and follow the approved emergency response
CIgnore it if refrigerant is nonflammable
DUse oxygen to ventilate

Why B is correct

Refrigerant can displace oxygen or create toxic, cardiac, frost, or flammability hazards. Unprotected investigation can incapacitate the responder.

2. A nitrogen cylinder is transported upright with the regulator attached and no restraint. What should change?

ACarry it with oily gloves
BRoll it by the valve
Cap and secure the cylinder
DHeat it to increase pressure

Why C is correct

A broken valve can turn a high-pressure cylinder into a projectile. Caps, restraint, approved carts, and clean compatible fittings control mechanical and pressure hazards.

3. A compressed-gas cylinder is rolled with its regulator exposed and no cap or cart restraint. What handling correction is necessary?

ACarry it with oily gloves
BRoll it by the valve
Cap and secure the cylinder using approved handling methods
DHeat it to increase pressure for the described HVAC equipment and measured operating conditions

Why C is correct

The best answer is: Cap and secure the cylinder using approved handling methods. A broken valve can turn a high-pressure cylinder into a projectile. Caps, restraint, approved carts, and clean compatible fittings control mechanical and pressure hazards. The transferred operating condition requires the same design, installation, diagnostic, or safety principle in a different HVAC context. The other choices skip a prerequisite, conflict with the listed procedure, or treat a symptom without controlling its cause.

4. A crew begins heavy rooftop replacement work during extreme heat. Which prevention and emergency provisions belong in the plan?

Heat-illness prevention plan
BLess water to reduce breaks for the described HVAC equipment and measured operating conditions
CNo buddy checks
DDark clothing only

Why A is correct

The best answer is: Heat-illness prevention plan. Roof surfaces intensify heat and new workers may not be acclimatized. California heat-illness controls must be active before symptoms appear. The transferred operating condition requires the same design, installation, diagnostic, or safety principle in a different HVAC context. The other choices skip a prerequisite, conflict with the listed procedure, or treat a symptom without controlling its cause.

42 more in the bank

Answers and explanations for these are in the app.

A chiller lift uses rigging without verified capacity or center of gravity. What should occur?
A disconnect cover must be opened for justified energized diagnostic work. What determines boundaries and PPE?
A filter change requires work inside an unprotected roof-edge zone. What should be provided?
A large refrigerant release occurs in a small machinery room and an oxygen-deficiency alarm activates. What should the worker do?
A packaged unit must be lifted to a roof. What should the lift plan verify?
A rooftop crew begins heavy work during a heat wave. What should the plan include?
A rooftop unit has line power, crankcase heat, control power, and stored capacitor energy. What must service isolation address?
A strong fuel-gas odor is detected in a mechanical room. What takes priority?
A technician adjusts a gas appliance in a room showing signs of flue-gas spillage. What is the priority?
A technician becomes dizzy while testing a boiler in a poorly vented room. What should happen?
A technician must work near an unprotected roof edge. What should planning provide?
A technician proposes heating a refrigerant cylinder with an open flame to speed charging. Is this acceptable?
A test plug is not rated for the proposed pressure. What should the supervisor do?
A worker must enter a plenum with limited access and fan hazards. What is required?
An acidic coil cleaner is used overhead. What controls should be selected?
An energized diagnostic task is justified at a 480-volt panel. What must be established?
Before servicing a rooftop unit with line voltage, control voltage, and possible stored energy, what is required?
Brazing is planned near combustible roofing and concealed wood. What controls are required?
Coil cleaner is being sprayed overhead in a poorly ventilated area. What should be reviewed before work?
Duct repair requires entry into a large plenum with limited access and possible atmospheric or mechanical hazards. What must occur?
Why may a fire watch continue after brazing ends?
A boiler technician becomes dizzy in a poorly ventilated room. What immediate response is appropriate?
A crane will place a packaged unit on a roof with offset lifting points. What must the qualified lift plan establish?
A lift plan lacks verified rigging capacity and the chiller's center of gravity. What should the supervisor do?
A machinery-room alarm signals possible oxygen deficiency after a large refrigerant release. What is the immediate worker response?
A pneumatic test assembly contains a plug rated below proposed pressure. How should the test plan change?
A refrigerant detection alarm sounds in a machinery room. What action precedes investigation?
A rooftop unit has line power, a separate control transformer, and stored capacitor energy. What must energy control accomplish before service?
A worker must crawl inside an air plenum with limited entry, fan hazards, and uncertain atmosphere. Which entry process is required?
A worker proposes warming a refrigerant cylinder with a torch. Is that acceptable?
An acidic coil product will be sprayed overhead inside a small room. What information controls ventilation, PPE, and emergency measures?
Brazing occurs beside roofing and hidden wood blocking. Which hot-work controls must remain in place?
Coil service places a technician within an unprotected roof-edge zone. What must the work plan provide?
Entry into a large return plenum involves limited access and moving fan components. What evaluation and isolation are required?
Flue products spill into a room while a technician adjusts burner input. Which safety step comes first?
Justified troubleshooting requires exposure to a 480-volt cabinet. Which energized-work safeguards must be established?
Opening an energized disconnect is justified for diagnostics. What determines shock boundaries, arc-flash controls, and PPE?
Overhead use of corrosive coil cleaner creates splash and vapor exposure. Which controls should the SDS drive?
Routine filter access lies inside a roof fall-hazard area. What protection and access are required?
Utility, control, crankcase-heater, and capacitor energy remain at a rooftop unit. Which sources must service isolation include?
Why can a fire watch be necessary after the brazing flame has been extinguished?
Workers smell strong fuel gas on entering a mechanical room. What should they do before searching for the leak?

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