WALMART MAINTENANCE Building Systems 4 — Questions and Answers
Question 1: What does a building automation system (BAS) primarily control?
- Security cameras and access control only
- HVAC, lighting, fire, and other building mechanical systems from a central interface (Correct answer)
- Point-of-sale terminals and inventory systems
- Employee scheduling and time tracking
Correct answer: HVAC, lighting, fire, and other building mechanical systems from a central interface
A BAS integrates and controls mechanical, electrical, and plumbing systems from a central platform to optimize efficiency and comfort.
Question 2: In a commercial refrigeration system, what is the role of the thermostatic expansion valve (TXV)?
- Compress refrigerant to high pressure
- Meter refrigerant flow into the evaporator to maintain proper superheat (Correct answer)
- Remove heat from the refrigerant at the condenser
- Separate oil from the refrigerant
Correct answer: Meter refrigerant flow into the evaporator to maintain proper superheat
The TXV precisely meters liquid refrigerant into the evaporator, controlling superheat to maximize efficiency without flooding the compressor.
Question 3: What is the purpose of a ground fault circuit interrupter (GFCI) outlet?
- Prevent circuit overloads
- Detect small current leaks to ground and cut power within milliseconds (Correct answer)
- Protect against voltage spikes
- Filter electrical noise from the circuit
Correct answer: Detect small current leaks to ground and cut power within milliseconds
GFCI outlets monitor current imbalance between hot and neutral conductors and trip in as little as 1/40th of a second to prevent electrocution.
Question 4: A commercial toilet is running continuously. What is the most likely cause?
- Clogged main drain line
- Worn or misaligned flapper or flush valve seal (Correct answer)
- Low water supply pressure
- Broken tank float arm
Correct answer: Worn or misaligned flapper or flush valve seal
A worn or misaligned flapper allows water to continuously leak from the tank into the bowl, causing the fill valve to run constantly.
Question 5: What is the function of a damper in an HVAC duct system?
- Filter particulates from airflow
- Control and regulate airflow volume through duct branches (Correct answer)
- Humidify supply air
- Reduce duct noise from turbulence
Correct answer: Control and regulate airflow volume through duct branches
Dampers are adjustable plates inside ducts that control the volume of airflow to different zones or areas of a building.
Question 6: In a commercial building, what does 'single-phase' versus 'three-phase' power primarily affect?
- Voltage level supplied to the building
- The type and size of electrical equipment and motors that can be used (Correct answer)
- Number of circuits in the distribution panel
- The grounding method required
Correct answer: The type and size of electrical equipment and motors that can be used
Three-phase power supports larger motors and industrial equipment more efficiently, while single-phase is typically used for standard outlets and lighting.
Question 7: What is the primary hazard associated with a cracked heat exchanger in a gas furnace?
- Reduced heating efficiency
- Carbon monoxide infiltration into supply air (Correct answer)
- Increased gas consumption
- Tripping the high-limit switch repeatedly
Correct answer: Carbon monoxide infiltration into supply air
A cracked heat exchanger allows combustion gases including deadly carbon monoxide to mix with and enter the supply air stream.
WALMART MAINTENANCE Building Systems 4
What does a building automation system (BAS) primarily control?