BOC Building Operator Certification — Questions and Answers

Question 1: Which fire extinguisher class is appropriate for a fire in an energized electrical motor control center?

Class B
Class K
Class C (Correct answer)
Class A

Correct answer: Class C

Class C agents are non-conductive and rated for energized electrical equipment fires.

Question 2: Under OSHA's Hazard Communication Standard, how many sections must a Safety Data Sheet have?

10
8
12
16 (Correct answer)

Correct answer: 16

GHS-aligned SDSs use a standardized 16-section format.

Question 3: What inspection procedure is essential for code compliance?

Inspection is only needed for final sign-off
Visual spot checks are sufficient
The client determines inspection requirements
Systematic inspection following established checklists and standards (Correct answer)

Correct answer: Systematic inspection following established checklists and standards

Systematic inspections using established checklists and industry standards ensure quality and compliance at every stage.

Question 4: Why are large refrigerant leaks in an enclosed mechanical room especially dangerous?

Refrigerants are always highly flammable
Refrigerant vapor is heavier than air and can displace oxygen (Correct answer)
Refrigerants raise the room's oxygen content
Refrigerants turn into carbon monoxide

Correct answer: Refrigerant vapor is heavier than air and can displace oxygen

Most halocarbon refrigerants are denser than air and can accumulate in low areas, creating an asphyxiation hazard.

Question 5: 'Low delta-T syndrome' in a chilled water plant means:

The cooling tower fans run constantly
Chilled water supply temperature is too high
The chiller's evaporator is freezing
The temperature difference between chilled water supply and return is lower than design (Correct answer)

Correct answer: The temperature difference between chilled water supply and return is lower than design

Low delta-T forces more flow and more chillers online, wasting energy.

Question 6: What device is required by plumbing codes to prevent contaminated water from flowing back into the potable water supply from a boiler or cooling tower makeup line?

Backflow prevention assembly (Correct answer)
Pressure-reducing valve
Strainer
Thermostatic mixing valve

Correct answer: Backflow prevention assembly

Backflow preventers such as RPZ assemblies protect potable water from cross-connections with hazardous systems.

Question 7: Which ENERGY STAR Portfolio Manager metric is commonly used to benchmark a commercial building's annual energy performance?

Seasonal energy efficiency ratio (SEER)
Power factor
Coefficient of performance (COP)
Energy Use Intensity (EUI) in kBtu/ft²/yr (Correct answer)

Correct answer: Energy Use Intensity (EUI) in kBtu/ft²/yr

EUI normalizes total annual energy use by floor area so buildings can be compared.

Question 8: An energy audit level that includes detailed analysis of capital-intensive measures with investment-grade savings estimates is typically called:

Benchmarking only
Detailed analysis of capital-intensive modifications (ASHRAE Level 3) (Correct answer)
Energy survey and analysis (ASHRAE Level 2)
Walk-through audit (ASHRAE Level 1)

Correct answer: Detailed analysis of capital-intensive modifications (ASHRAE Level 3)

ASHRAE Level 3 audits give investment-grade analysis for major capital projects.

Question 9: A rising pressure drop across an air handler filter bank indicates:

The outdoor damper has closed
The filters are loading and approaching replacement (Correct answer)
The fan belt is broken
The filters are missing

Correct answer: The filters are loading and approaching replacement

Dirt buildup increases resistance, shown by higher differential pressure.

Question 10: Which refrigerant property measures a substance's ability to destroy stratospheric ozone?

Saturation pressure
Ozone depletion potential (ODP) (Correct answer)
Coefficient of performance (COP)
Global warming potential (GWP)

Correct answer: Ozone depletion potential (ODP)

ODP rates ozone-destroying ability relative to CFC-11, which is assigned a value of 1.0.

Question 11: What is the purpose of using motion sensors in lighting systems?

Prevent electrical surges
Reduce energy by turning off unused lights (Correct answer)
Control HVAC systems
Increase brightness during peak hours

Correct answer: Reduce energy by turning off unused lights

Motion sensors help save energy by automatically turning lights on when movement is detected and off when the space is unoccupied.

Question 12: How does regular maintenance contribute to energy conservation?

Reduces system efficiency
Improves equipment efficiency (Correct answer)
Increases emergency repairs
Causes more system downtime

Correct answer: Improves equipment efficiency

Well-maintained systems operate more efficiently, reducing wasted energy and extending equipment life.

Question 13: What environmental protection measure applies to safety procedures?

Follow environmental rules only if specifically asked
Proper handling, storage, and disposal of materials according to environmental regulations (Correct answer)
Environmental rules only apply to large corporations
Environmental concerns do not apply to this field

Correct answer: Proper handling, storage, and disposal of materials according to environmental regulations

Proper handling, storage, and disposal of all materials according to environmental regulations is a legal obligation in all trades.

Question 14: What is the role of a sensor's 'setpoint' in a BAS control loop?

The maximum voltage the sensor can handle
The calibration offset applied to raw sensor data
The desired target value the control system works to achieve and maintain (Correct answer)
The frequency at which the sensor transmits data

Correct answer: The desired target value the control system works to achieve and maintain

A setpoint is the target value (e.g., 72°F room temperature) that the controller continuously compares to the measured value to determine the corrective action needed.

Question 15: The Color Rendering Index (CRI) of a lamp indicates:

How warm or cool the light appears
How many hours the lamp will last
How much heat the lamp gives off
How accurately it shows object colors compared with a reference source (Correct answer)

Correct answer: How accurately it shows object colors compared with a reference source

CRI, on a scale up to 100, rates how faithfully a light source renders colors compared with a reference illuminant.

Question 16: To reduce Legionella growth in domestic hot water systems, at what minimum temperature should water heaters typically store water?

180°F (82°C)
105°F (41°C)
120°F (49°C)
140°F (60°C) (Correct answer)

Correct answer: 140°F (60°C)

Storing hot water at 140°F (60°C) or above suppresses Legionella, which grows best between about 77°F and 113°F.

Question 17: Once a leak is found in an appliance over the threshold, how many days does the owner generally have to repair it?

90 days
7 days
14 days
30 days (Correct answer)

Correct answer: 30 days

EPA generally allows 30 days to repair leaks once an appliance exceeds the applicable leak rate.

Question 18: In the galvanic series, which metal will corrode first when coupled with copper in an electrolyte?

Zinc (Correct answer)
Stainless steel (passive)
Silver
Gold

Correct answer: Zinc

Zinc is more anodic than copper and will corrode preferentially when the two are coupled.

Question 19: Demand-controlled ventilation typically modulates outdoor air based on:

Supply duct static pressure
Space CO2 concentration (Correct answer)
Filter pressure drop
Chilled water temperature

Correct answer: Space CO2 concentration

CO2 serves as a proxy for occupancy, adjusting ventilation to actual need.

Question 20: Which ASHRAE standard defines conditions for human thermal comfort in occupied spaces?

ASHRAE Standard 15
ASHRAE Standard 62.1
ASHRAE Standard 55 (Correct answer)
ASHRAE Standard 90.1

Correct answer: ASHRAE Standard 55

ASHRAE 55 specifies the combinations of temperature, humidity, air speed, and other factors that produce acceptable thermal comfort.

Question 21: What is the most critical safety requirement in quality inspection?

Cost minimization
Following all applicable safety regulations and wearing required PPE (Correct answer)
Speed of completion
Working alone to avoid delays

Correct answer: Following all applicable safety regulations and wearing required PPE

Safety regulations and proper PPE use are the most critical requirements in quality inspection to prevent injury and ensure compliance.

Question 22: Which ASHRAE standard sets requirements for managing Legionella risk in building water systems?

ASHRAE 188 (Correct answer)
ASHRAE 62.1
ASHRAE 55
ASHRAE 90.1

Correct answer: ASHRAE 188

ASHRAE 188 requires a water management program to reduce Legionellosis risk.

Question 23: How should equipment be maintained for safety procedures operations?

Follow manufacturer-recommended preventive maintenance schedules (Correct answer)
Inspect equipment annually only
Fix equipment only when it breaks
Maintenance is optional for newer equipment

Correct answer: Follow manufacturer-recommended preventive maintenance schedules

Preventive maintenance following manufacturer recommendations ensures equipment reliability, safety, and longevity.

Question 24: Why is CPVC rather than standard PVC used for some hot water piping?

CPVC is cheaper
CPVC has a higher temperature rating (Correct answer)
CPVC does not need fittings
CPVC is more flexible

Correct answer: CPVC has a higher temperature rating

CPVC is chlorinated to tolerate temperatures up to about 180°F, while standard PVC is rated near 140°F.

Question 25: A demand-controlled ventilation (DCV) system typically adjusts outdoor air intake based on which measurement?

Space CO2 concentration (Correct answer)
Duct static pressure
Outdoor air temperature
Supply air humidity

Correct answer: Space CO2 concentration

DCV uses CO2 levels as a proxy for occupancy and lowers ventilation when fewer people are present.

Question 26: What code compliance requirement applies to environmental standards?

Codes are guidelines, not requirements
Follow codes only when inspectors are present
Code compliance only matters for commercial projects
All work must comply with applicable local, state, and national codes (Correct answer)

Correct answer: All work must comply with applicable local, state, and national codes

Code compliance is mandatory for all work, ensuring safety, quality, and legal adherence.

Question 27: According to NFPA 101 Life Safety Code, battery-powered emergency egress lighting must operate for at least:

30 minutes
90 minutes (Correct answer)
8 hours
4 hours

Correct answer: 90 minutes

NFPA 101 requires emergency lighting to provide illumination for a minimum of 1½ hours after loss of normal power.

Question 28: Which plumbing fixture feature is most effective at reducing building water consumption in restrooms?

Larger drain lines
Low-flow aerators and 1.28 gpf high-efficiency toilets (Correct answer)
Insulated supply pipes
Automatic flush sensors

Correct answer: Low-flow aerators and 1.28 gpf high-efficiency toilets

Low-flow aerators reduce faucet flow while maintaining usability, and 1.28 gpf HET toilets use significantly less water per flush than standard 1.6 gpf models.

Question 29: Under federal regulations, how are spent mercury-containing fluorescent lamps typically managed?

As universal waste (Correct answer)
As medical waste
As municipal solid waste
As radioactive waste

Correct answer: As universal waste

EPA's universal waste rule makes collecting and recycling common hazardous items like mercury lamps simpler.

Question 30: Air compressor systems often waste energy mainly through:

Leaks in distribution piping and fittings (Correct answer)
Excessively large receiver tanks
Low discharge pressure settings
Using synthetic lubricants

Correct answer: Leaks in distribution piping and fittings

Leaks can waste 20–30% of compressor output, so leak detection and repair is a key conservation measure.

Question 31: When setting up a portable extension ladder to access a roof, what is the recommended angle ratio?

1 foot out for every 4 feet of height (Correct answer)
1 foot out for every 2 feet of height
1 foot out for every 8 feet of height
Base flush against the wall

Correct answer: 1 foot out for every 4 feet of height

The 4-to-1 rule places the ladder at about 75 degrees for stability.

Question 32: Which method best reduces simultaneous heating and cooling in a building?

Widen the deadband between heating and cooling setpoints (Correct answer)
Raise the minimum outdoor air
Run boilers and chillers on the same schedule year-round
Narrow the thermostat deadband to 0°F

Correct answer: Widen the deadband between heating and cooling setpoints

A wider deadband keeps heating and cooling from fighting each other in the same space.

Question 33: Approximately how many inches of water column equal 1 psi?

2.31 in. w.c.
14.7 in. w.c.
0.433 in. w.c.
27.7 in. w.c. (Correct answer)

Correct answer: 27.7 in. w.c.

1 psi equals about 27.7 inches of water column (2.31 feet × 12).

Question 34: Hearing conservation programs are required by OSHA when employee noise exposure reaches what 8-hour time-weighted average?

90 dBA
70 dBA
85 dBA (Correct answer)
100 dBA

Correct answer: 85 dBA

OSHA's action level of 85 dBA TWA triggers a hearing conservation program, including audiometric testing.

Question 35: The differential pressure across an AHU filter bank has risen steadily to the manufacturer's recommended final resistance. What should the operator do?

Lower the supply air temperature setpoint
Replace the filters (Correct answer)
Remove the filters to restore airflow
Increase fan speed to compensate

Correct answer: Replace the filters

Reaching final resistance means the filters are loaded and should be replaced to keep airflow and filtration up.

Question 36: What is the most critical safety requirement in equipment operation?

Cost minimization
Following all applicable safety regulations and wearing required PPE (Correct answer)
Speed of completion
Working alone to avoid delays

Correct answer: Following all applicable safety regulations and wearing required PPE

Safety regulations and proper PPE use are the most critical requirements in equipment operation to prevent injury and ensure compliance.

Question 37: Which indoor device can be a source of ozone if poorly maintained or improperly selected?

Variable frequency drive
Enthalpy wheel
HEPA filter
Electronic air cleaner or ionizer (Correct answer)

Correct answer: Electronic air cleaner or ionizer

Some electrostatic precipitators, ionizers, and ozone generators release ozone, a lung irritant.

Question 38: What environmental protection measure applies to environmental standards?

Follow environmental rules only if specifically asked
Environmental concerns do not apply to this field
Proper handling, storage, and disposal of materials according to environmental regulations (Correct answer)
Environmental rules only apply to large corporations

Correct answer: Proper handling, storage, and disposal of materials according to environmental regulations

Proper handling, storage, and disposal of all materials according to environmental regulations is a legal obligation in all trades.

Question 39: Renovation work that disturbs painted surfaces in a building constructed before which year triggers the EPA's lead Renovation, Repair and Painting (RRP) rule in target housing and child-occupied facilities?

2000
1990
1950
1978 (Correct answer)

Correct answer: 1978

Residential lead-based paint was banned in the U.S. in 1978, so the RRP rule applies to pre-1978 target housing and child-occupied facilities.

Question 40: What device measures the amount of electrical energy consumed?

Transformer
Switchgear
Circuit breaker
Electric meter (Correct answer)

Correct answer: Electric meter

An electric meter tracks the amount of electrical energy used over time, typically in kilowatt-hours (kWh).

Question 41: What is the function of a thermostatic mixing valve (TMV) at a building's hot water system?

To regulate incoming water pressure
To divert hot water to priority zones first
To blend cold and recirculated water to prevent freezing
To blend hot and cold water to deliver a safe, scalding-free temperature at fixtures (Correct answer)

Correct answer: To blend hot and cold water to deliver a safe, scalding-free temperature at fixtures

A TMV mixes hot storage water (maintained at high temperature for Legionella control) with cold water to deliver tempered water at a safe use temperature, typically 110°F.

Question 42: EPA's Renovation, Repair and Painting (RRP) Rule applies to work that disturbs paint in housing and child-occupied facilities built before what year?

1990
1978 (Correct answer)
1970
1960

Correct answer: 1978

Lead-based paint was banned for residential use in 1978, so the RRP rule covers buildings built before then.

Question 43: What is the main function of a steam trap?

To drain condensate and non-condensable gases while holding back live steam (Correct answer)
To stop water hammer by injecting air
To lower steam pressure
To control steam flow to coils

Correct answer: To drain condensate and non-condensable gases while holding back live steam

Steam traps automatically drain condensate and air without letting live steam escape.

Question 44: As of January 1, 2020, what happened to production and import of virgin R-22 in the United States?

It was banned, so only recovered or reclaimed R-22 can be used (Correct answer)
It was cut by 50%
It became limited to new equipment only
It was replaced by mandatory R-12 use

Correct answer: It was banned, so only recovered or reclaimed R-22 can be used

The R-22 phaseout ended new production and import, so servicing now depends on recovered, recycled, or reclaimed supply.

Question 45: A GFCI device trips when it detects a current imbalance of approximately how much?

500 milliamps
50 milliamps
5 milliamps (Correct answer)
5 amps

Correct answer: 5 milliamps

Class A GFCIs trip at about 4 to 6 mA of leakage to protect people from shock.

Question 46: Which measure reduces energy used for domestic hot water in an office building with minimal capital cost?

Increasing hot water pipe diameter
Lowering the water heater setpoint to about 120°F where codes allow (Correct answer)
Installing a larger storage tank
Adding a second recirculation pump

Correct answer: Lowering the water heater setpoint to about 120°F where codes allow

A lower setpoint reduces standby losses and heating energy, and 120°F is generally enough for handwashing.

Question 47: What does a MERV rating on an air filter indicate?

The filter's fire resistance
The filter's maximum airflow in CFM
The filter's expected service life
The filter's ability to capture particles of specific sizes (Correct answer)

Correct answer: The filter's ability to capture particles of specific sizes

MERV (Minimum Efficiency Reporting Value) rates how well a filter captures particles from 0.3 to 10 microns.

Question 48: When choosing a lubricant for a motor bearing, what is the most important consideration?

Following the manufacturer's specified type and grade (Correct answer)
Mixing greases to improve performance
Using the thickest grease available
Using any multipurpose grease on hand

Correct answer: Following the manufacturer's specified type and grade

Incompatible or wrong-grade lubricants can break down and cause bearing failure, so follow manufacturer specs.

Question 49: Which lamp choice typically gives the longest life and lowest energy use when relamping a building?

LED (Correct answer)
T12 fluorescent
Halogen
Incandescent

Correct answer: LED

LEDs offer the highest efficacy and longest rated life among common building lamps.

Question 50: What environmental protection measure applies to maintenance protocols?

Follow environmental rules only if specifically asked
Environmental rules only apply to large corporations
Proper handling, storage, and disposal of materials according to environmental regulations (Correct answer)
Environmental concerns do not apply to this field

Correct answer: Proper handling, storage, and disposal of materials according to environmental regulations

Proper handling, storage, and disposal of all materials according to environmental regulations is a legal obligation in all trades.

Question 51: What minimum MERV rating do ASHRAE and CDC guidance commonly recommend for HVAC filters to capture airborne particles more effectively?

MERV 8
MERV 13 (Correct answer)
MERV 20
MERV 4

Correct answer: MERV 13

MERV 13 filters capture a high share of fine particles in the 0.3–10 micron range when the system can handle them.

Question 52: Which practice reduces peak electrical demand charges without necessarily lowering total kWh consumed?

Installing occupancy sensors
Load shifting with thermal energy storage (Correct answer)
Sealing duct leaks
Lowering domestic hot water temperature

Correct answer: Load shifting with thermal energy storage

Thermal storage moves cooling production to off-peak hours, which lowers kW demand at peak times.

Question 53: How should equipment be maintained for equipment operation operations?

Maintenance is optional for newer equipment
Inspect equipment annually only
Fix equipment only when it breaks
Follow manufacturer-recommended preventive maintenance schedules (Correct answer)

Correct answer: Follow manufacturer-recommended preventive maintenance schedules

Preventive maintenance following manufacturer recommendations ensures equipment reliability, safety, and longevity.

Question 54: A facility stores more than how many gallons of oil aboveground in total, triggering an EPA SPCC plan requirement?

10,000 gallons
55 gallons
1,320 gallons (Correct answer)
500 gallons

Correct answer: 1,320 gallons

An SPCC plan is required when aboveground oil storage capacity exceeds 1,320 gallons, counting containers of 55 gallons or more.

Question 55: Which pipe material is generally preferred for domestic hot water distribution in commercial buildings because it resists corrosion and handles high temperatures?

ABS
Galvanized steel
PVC Schedule 40
Type L copper (Correct answer)

Correct answer: Type L copper

Type L copper is the common choice for hot and cold domestic water because of its durability and temperature tolerance.

Question 56: Indoor CO2 readings are commonly compared to outdoor levels to judge ventilation. Roughly what is the typical outdoor CO2 concentration today?

About 5,000 ppm
About 420 ppm (Correct answer)
About 100 ppm
About 1,500 ppm

Correct answer: About 420 ppm

Outdoor CO2 is now about 420 ppm, and indoor readings far above this suggest too little outdoor air.

Question 57: A proportional-only controller holding a space at 74°F when the setpoint is 72°F is exhibiting:

Offset (droop) (Correct answer)
Hunting
Short cycling
Deadband

Correct answer: Offset (droop)

Proportional-only control needs some error to produce output, causing a steady offset.

Question 58: Elastomeric closed-cell insulation is commonly selected for which application?

High-pressure steam lines
Boiler breeching
Refrigerant suction lines (Correct answer)
Furnace flues

Correct answer: Refrigerant suction lines

Elastomeric foam is flexible, has a built-in vapor resistance, and suits cold refrigerant lines.

Question 59: Which control strategy modulates equipment output proportionally to the difference between the measured value and the setpoint?

Duty cycling
On/off (two-position) control
Time-of-day scheduling
Proportional control (Correct answer)

Correct answer: Proportional control

Proportional control adjusts output (e.g., valve position) in direct proportion to the error signal (difference between measured value and setpoint), providing smoother control than simple on/off.

Question 60: What is the purpose of 'optimal start' programming in a BAS?

To stagger equipment starts to avoid electrical demand spikes
To calculate the latest start time that still brings the building to setpoint by occupancy (Correct answer)
To start equipment at the earliest possible time regardless of conditions
To pre-cool the building during the hottest summer afternoons

Correct answer: To calculate the latest start time that still brings the building to setpoint by occupancy

Optimal start uses historical data and outdoor temperature to calculate the latest possible start time that allows the HVAC system to reach comfort setpoints just as occupancy begins.

Question 61: In which water temperature range does Legionella bacteria grow most readily?

Above 160°F
77–113°F (Correct answer)
32–50°F
130–150°F

Correct answer: 77–113°F

Legionella grows best between about 77°F and 113°F (25–45°C), which is common in warm water systems.

Question 62: What environmental protection measure applies to material selection?

Environmental rules only apply to large corporations
Proper handling, storage, and disposal of materials according to environmental regulations (Correct answer)
Environmental concerns do not apply to this field
Follow environmental rules only if specifically asked

Correct answer: Proper handling, storage, and disposal of materials according to environmental regulations

Proper handling, storage, and disposal of all materials according to environmental regulations is a legal obligation in all trades.

Question 63: Why are capacitor banks commonly installed in buildings with many large induction motors?

To raise the supply voltage above nameplate
To correct a lagging power factor (Correct answer)
To filter lightning surges
To reduce kWh consumed by lighting

Correct answer: To correct a lagging power factor

Capacitors supply leading reactive power that offsets the lagging reactive power drawn by inductive motors.

Question 64: Which type of stored energy must be released or restrained during lockout of a hydronic heating system?

None, since water is non-hazardous
Only the electrical supply to the circulator
Only the gas supply to the boiler
Residual water pressure and heat in the piping (Correct answer)

Correct answer: Residual water pressure and heat in the piping

Stored hydraulic pressure and thermal energy in hot-water piping can cause burns or injury and must be relieved.

Question 65: Which type of backflow preventer is usually required on high-hazard connections and must be tested at least once a year?

Double check valve assembly
Atmospheric vacuum breaker
Hose bibb vacuum breaker
Reduced pressure zone (RPZ) assembly (Correct answer)

Correct answer: Reduced pressure zone (RPZ) assembly

RPZ assemblies protect high-hazard cross-connections, and most jurisdictions require annual testing.

Question 66: Which retrofit typically gives the greatest lighting energy reduction in a warehouse with high-intensity discharge fixtures?

Swapping to higher-wattage metal halide lamps
Adding more fixtures at lower mounting height
LED high-bay fixtures with occupancy controls (Correct answer)
Replacing lenses with clear glass

Correct answer: LED high-bay fixtures with occupancy controls

LED high-bays use far fewer watts than HID and can instantly dim or switch off with occupancy sensors.

Question 67: Before touching conductors on a locked-out circuit, how should an operator verify that it is de-energized?

Touch the conductor briefly with the back of the hand
Test a known live source, test the circuit, then retest the known source with a rated meter (Correct answer)
Check that the lights on the circuit are off
Confirm the breaker handle is in the OFF position

Correct answer: Test a known live source, test the circuit, then retest the known source with a rated meter

The live-dead-live test shows the meter works both before and after it confirms the circuit has no voltage.

Question 68: A boiler's Hartford Loop is designed to protect against:

Siphoning of water out of the boiler (Correct answer)
Overpressure conditions
Waterlogging of steam radiators
Excessive flue gas temperatures

Correct answer: Siphoning of water out of the boiler

The Hartford Loop prevents gravity-fed water from siphoning back out of the boiler through a return line leak, which could expose the heating elements.

Question 69: What is the primary purpose of a freezestat on an air handling unit?

To measure outdoor humidity
To shut down the fan or close outdoor dampers when air entering the coil nears freezing (Correct answer)
To control the discharge air temperature setpoint
To reset the chilled water temperature

Correct answer: To shut down the fan or close outdoor dampers when air entering the coil nears freezing

A freezestat, typically set near 38°F, protects water coils from freeze damage.

Question 70: In a building's domestic hot water system, what is the purpose of a recirculation loop?

To ensure hot water is quickly available at fixtures without long wait times (Correct answer)
To increase water heater capacity
To allow dual-temperature zones
To reduce incoming cold water pressure

Correct answer: To ensure hot water is quickly available at fixtures without long wait times

A recirculation loop continuously circulates hot water through the distribution piping so occupants get near-instant hot water at any fixture.

Question 71: What is the function of a circuit breaker in an electrical system?

Increase voltage
Protect against overcurrent (Correct answer)
Measure electricity usage
Balance electrical loads

Correct answer: Protect against overcurrent

A circuit breaker protects an electrical circuit from damage caused by overcurrent or short circuit by interrupting the flow of electricity.

Question 72: What is the main advantage of infrared thermography in electrical maintenance?

It finds loose or overloaded connections as hot spots while equipment stays energized (Correct answer)
It replaces the need for lockout/tagout
It measures motor insulation resistance
It measures power factor

Correct answer: It finds loose or overloaded connections as hot spots while equipment stays energized

Thermal imaging spots abnormal heating at connections and components without shutting down equipment.

Question 73: Under the fan affinity laws, reducing a fan's speed to 80% with a VFD lowers its power draw to roughly:

About 80% of full power
About 51% of full power (Correct answer)
About 20% of full power
About 64% of full power

Correct answer: About 51% of full power

Power varies with the cube of speed, and 0.8³ ≈ 0.51.

Question 74: What is the role of a thermostat in HVAC systems?

Control water pressure
Regulate temperature by controlling the system (Correct answer)
Supply refrigerant
Measure humidity only

Correct answer: Regulate temperature by controlling the system

Thermostats sense room temperature and signal HVAC equipment to turn on or off to maintain desired conditions.

Question 75: The MERV filter efficiency rating comes from which ASHRAE test standard?

ASHRAE Standard 52.2 (Correct answer)
ASHRAE Standard 62.2
ASHRAE Standard 55
ASHRAE Standard 100

Correct answer: ASHRAE Standard 52.2

ASHRAE 52.2 sets the test method for particle removal efficiency that produces Minimum Efficiency Reporting Values.

Question 76: Testable backflow prevention assemblies such as reduced pressure zone (RPZ) valves are typically required to be tested how often?

Every 10 years
Every 5 years
At least annually (Correct answer)
Only at installation

Correct answer: At least annually

Most U.S. jurisdictions require RPZ and double-check assemblies to be tested by a certified tester at least once a year.

Question 77: What is the most critical safety requirement in technical measurements?

Following all applicable safety regulations and wearing required PPE (Correct answer)
Cost minimization
Working alone to avoid delays
Speed of completion

Correct answer: Following all applicable safety regulations and wearing required PPE

Safety regulations and proper PPE use are the most critical requirements in technical measurements to prevent injury and ensure compliance.

Question 78: What is the minimum ENERGY STAR score a building must earn to qualify for ENERGY STAR certification?

75 (Correct answer)
90
65
50

Correct answer: 75

A score of 75 or higher means the building outperforms at least 75% of similar buildings nationwide.

Question 79: What is 'demand-controlled ventilation' (DCV) and what sensor drives it?

Ventilation controlled by outdoor air temperature using a thermostat
Ventilation rate modulated based on occupancy using CO₂ sensors (Correct answer)
Ventilation scheduled by time-of-day programming
Ventilation controlled by humidity sensors to prevent condensation

Correct answer: Ventilation rate modulated based on occupancy using CO₂ sensors

DCV uses CO₂ sensors as a proxy for occupancy; when CO₂ levels rise (more people), outdoor air flow increases, and when levels drop, ventilation is reduced to save energy.

Question 80: Occupants on the lower floors report diesel exhaust odors each morning when deliveries arrive. What is the most likely cause?

The outdoor air intake is located near the loading dock (Correct answer)
The chilled water temperature is too low
The building is positively pressurized
The return air filters are dirty

Correct answer: The outdoor air intake is located near the loading dock

An outdoor air intake near a loading dock draws in vehicle exhaust, so ASHRAE 62.1 sets minimum separation distances.

Question 81: What is the purpose of a steam trap maintenance survey?

To measure boiler stack temperature
To check feedwater hardness
To find traps that are failed open or closed, which waste steam or cause water hammer (Correct answer)
To adjust the burner air-fuel ratio

Correct answer: To find traps that are failed open or closed, which waste steam or cause water hammer

Failed-open traps waste steam energy, and failed-closed traps back up condensate, so regular surveys pay off quickly.

Question 82: An LED fixture with an L70 rating of 50,000 hours is expected to:

Use 70% less energy than fluorescent for 50,000 hours
Fail completely after 50,000 hours
Operate at 70 °C for 50,000 hours
Keep at least 70% of its initial light output for 50,000 hours (Correct answer)

Correct answer: Keep at least 70% of its initial light output for 50,000 hours

L70 is the point at which lumen output falls to 70% of the initial value, since LEDs usually dim gradually instead of burning out.

Question 83: One kilowatt of electric power is equivalent to approximately how many Btu per hour?

746 Btu/h
1,000 Btu/h
12,000 Btu/h
3,412 Btu/h (Correct answer)

Correct answer: 3,412 Btu/h

1 kW equals about 3,412 Btu/h, the standard conversion for electric heat.

Question 84: What does the term 'blowdown' refer to in boiler operation?

Removing accumulated solids and impurities from boiler water (Correct answer)
Purging combustion gases from the firebox
Draining condensate from steam traps
Releasing excess steam pressure through a safety valve

Correct answer: Removing accumulated solids and impurities from boiler water

Blowdown removes dissolved and suspended solids that concentrate in boiler water, preventing scale buildup and maintaining water quality.

Question 85: Lowering condenser water supply temperature (within manufacturer limits) generally:

Improves chiller efficiency but may increase cooling tower fan energy (Correct answer)
Lowers chiller efficiency
Has no effect on chiller kW/ton
Reduces chilled water flow

Correct answer: Improves chiller efficiency but may increase cooling tower fan energy

Cooler condenser water reduces compressor lift, but the tower fans may run harder, so the total plant energy has to be optimized.

Question 86: What is the apparent power of a balanced three-phase load at 480 V and 100 A?

83.1 kVA (Correct answer)
27.7 kVA
144 kVA
48.0 kVA

Correct answer: 83.1 kVA

Three-phase kVA = V × I × 1.732 ÷ 1,000 = 480 × 100 × 1.732 ÷ 1,000 ≈ 83.1 kVA.

Question 87: Simple payback for an energy conservation measure is calculated as:

Annual savings − installed cost
Installed cost × annual savings
Annual savings ÷ installed cost
Installed cost ÷ annual savings (Correct answer)

Correct answer: Installed cost ÷ annual savings

Simple payback in years equals the project cost divided by the annual dollar savings.

Question 88: Which type of boiler operates at steam pressures above 15 psig?

Low-pressure boiler
Condensate boiler
High-pressure boiler (Correct answer)
Hot water boiler

Correct answer: High-pressure boiler

High-pressure boilers are defined as those operating at steam pressures exceeding 15 psig, requiring more stringent safety and licensing requirements.

Question 89: A fire door is found propped open with a wedge. What is the code compliance issue?

It only matters if the door is in a stairwell
None, if the door is labeled
Fire doors must be self-closing and latching and must not be blocked open (Correct answer)
Only a problem after business hours

Correct answer: Fire doors must be self-closing and latching and must not be blocked open

Fire doors must close and latch automatically; wedges defeat this, and only listed hold-open devices released by alarm are allowed.

Question 90: What inspection procedure is essential for equipment operation?

Visual spot checks are sufficient
The client determines inspection requirements
Inspection is only needed for final sign-off
Systematic inspection following established checklists and standards (Correct answer)

Correct answer: Systematic inspection following established checklists and standards

Systematic inspections using established checklists and industry standards ensure quality and compliance at every stage.

Question 91: What indoor radon level does EPA recommend as the action level for mitigation?

2 pCi/L
1 pCi/L
4 pCi/L (Correct answer)
10 pCi/L

Correct answer: 4 pCi/L

EPA recommends mitigation when radon is at or above 4 picocuries per liter.

Question 92: In a cooling tower water treatment program, why is biocide treatment essential?

To reduce blowdown frequency
To lower the pH of the recirculating water
To prevent scale on condenser tubes
To control microbial growth including Legionella and algae (Correct answer)

Correct answer: To control microbial growth including Legionella and algae

Cooling towers are warm, aerated water environments ideal for microbial growth; biocide treatment kills bacteria, algae, and biofilm to protect health and system performance.

Question 93: What does a pressure-reducing valve (PRV) do in a building water system?

Regulates flow rate to individual fixtures
Prevents water hammer in supply lines
Boosts incoming water pressure to upper floors
Steps down high street main pressure to a safe working pressure inside the building (Correct answer)

Correct answer: Steps down high street main pressure to a safe working pressure inside the building

A PRV reduces and stabilizes high incoming municipal water pressure to a safe level, typically 60–80 psi, to protect fixtures and piping from damage.

Question 94: In a three-phase, four-wire system serving many computers, LED drivers, and VFDs, what problem can harmonic currents cause?

Higher power factor than unity
Overheating of the shared neutral conductor (Correct answer)
Reduced lamp color temperature
Elimination of voltage drop

Correct answer: Overheating of the shared neutral conductor

Triplen harmonics add together in the neutral rather than canceling, which can overload it.

Question 95: Why is emergency lighting important in building safety?

To enhance ambient design
To guide occupants during emergencies (Correct answer)
To improve daylight savings
To reduce energy costs

Correct answer: To guide occupants during emergencies

Emergency lighting provides visibility during power outages or emergencies, guiding occupants to safety.

Question 96: What indoor relative humidity range is generally recommended to limit mold growth and occupant discomfort?

10–20%
30–60% (Correct answer)
85–95%
65–80%

Correct answer: 30–60%

Keeping RH between about 30% and 60% discourages mold and dust mites while staying comfortable.

Question 97: When verifying the absence of voltage with a meter, what should be done before and after testing the circuit?

Test the meter on a known live source (Correct answer)
Replace the meter batteries
Ground the meter leads to the panel
Calibrate the meter to zero ohms only

Correct answer: Test the meter on a known live source

The live-dead-live test confirms the meter is working so a dead reading can be trusted.

Question 98: Under OSHA lockout/tagout rules, who is normally allowed to remove a personal lockout device?

The building manager
Any qualified electrician on site
The next shift's lead operator
The employee who applied it (Correct answer)

Correct answer: The employee who applied it

Each lock must be removed by the worker who installed it, except under strict documented emergency removal procedures.

Question 99: Under NFPA 80, how often must swinging fire door assemblies be inspected and tested?

Every 5 years
Every 3 years
Monthly
Annually (Correct answer)

Correct answer: Annually

NFPA 80 requires fire door assemblies to be inspected and tested at least annually with written records.

Question 100: How should hazardous conditions be handled during equipment operation work?

Report hazards only at the end of the day
Continue working if the hazard seems minor
Let someone else deal with it
Stop work, secure the area, report the hazard, and follow safety protocols (Correct answer)

Correct answer: Stop work, secure the area, report the hazard, and follow safety protocols

All hazardous conditions require immediate action: stop work, secure the area, report the hazard, and follow established safety protocols.

Question 101: Before entering a permit-required confined space, in what order should the atmosphere be tested?

Flammables, oxygen, toxic gases
Oxygen, toxic gases, flammables
Oxygen, flammables, toxic gases (Correct answer)
Toxic gases, flammables, oxygen

Correct answer: Oxygen, flammables, toxic gases

Test oxygen first because combustible-gas sensors need enough oxygen to read accurately, then flammables, then toxics.

Question 102: Under the fan affinity laws, if fan speed is cut in half, what happens to fan horsepower?

It drops to one-quarter
It drops to about one-eighth (Correct answer)
It drops to one-half
It stays the same

Correct answer: It drops to about one-eighth

Fan power varies with the cube of speed, so (1/2)^3 = 1/8.

Question 103: In many U.S. commercial buildings with a 480Y/277 V service, what is the 277 V line-to-neutral circuit most commonly used for?

Large fluorescent and LED lighting systems (Correct answer)
Receptacles for office equipment
Residential-style kitchen appliances
Low-voltage thermostat control wiring

Correct answer: Large fluorescent and LED lighting systems

Commercial lighting is often fed at 277 V to reduce current and conductor size.

Question 104: How should equipment be maintained for maintenance protocols operations?

Fix equipment only when it breaks
Follow manufacturer-recommended preventive maintenance schedules (Correct answer)
Maintenance is optional for newer equipment
Inspect equipment annually only

Correct answer: Follow manufacturer-recommended preventive maintenance schedules

Preventive maintenance following manufacturer recommendations ensures equipment reliability, safety, and longevity.

Question 105: What does 'blowdown' refer to in the context of a cooling tower or boiler water system?

Purging a portion of the recirculating water to remove concentrated dissolved solids (Correct answer)
Increasing water flow rate to flush sediment
Emergency venting of steam pressure
Removing scale from heat exchanger surfaces

Correct answer: Purging a portion of the recirculating water to remove concentrated dissolved solids

Blowdown is the controlled discharge of a portion of the recirculating water to prevent dissolved minerals from concentrating to levels that cause scale or corrosion.

Question 106: What is the primary benefit of implementing energy conservation strategies in buildings?

Improves aesthetics
Enhances noise levels
Increases labor costs
Reduces energy use and costs (Correct answer)

Correct answer: Reduces energy use and costs

Energy conservation helps reduce operating costs, environmental impact, and improves building efficiency.

Question 107: Which standard covers electrical safety in the workplace, including arc-flash risk assessment and PPE?

NFPA 70E (Correct answer)
NFPA 13
NFPA 110
NFPA 72

Correct answer: NFPA 70E

NFPA 70E sets requirements for electrical safety-related work practices, including arc-flash hazard analysis.

Question 108: Before a technician works on an air handler fan, which step is required under OSHA lockout/tagout rules after applying the lock?

Notify the utility company
Remove the fan belt first
Open all the outside air dampers
Verify zero energy by trying to start the equipment or by testing (Correct answer)

Correct answer: Verify zero energy by trying to start the equipment or by testing

OSHA 1910.147 requires verifying that energy is isolated, for example by trying the start control, before work begins.

Question 109: An occupant's symptoms go away soon after they leave the building, and no specific cause can be identified. What is this condition called?

Building-related illness
Multiple chemical sensitivity
Legionnaires' disease
Sick building syndrome (Correct answer)

Correct answer: Sick building syndrome

Sick building syndrome has nonspecific symptoms tied to time spent in a building, and no cause can be identified.

Question 110: Why is cooling tower water bled off (blowdown)?

To lower the fan speed
To control the concentration of dissolved solids left behind by evaporation (Correct answer)
To prevent freezing
To raise the water's pH

Correct answer: To control the concentration of dissolved solids left behind by evaporation

Evaporation concentrates minerals, so bleed-off limits cycles of concentration and prevents scale.

Question 111: In a 208Y/120 V three-phase system, what is the voltage measured from any phase conductor to neutral?

208 V
240 V
120 V (Correct answer)
277 V

Correct answer: 120 V

In a wye system, line-to-neutral voltage equals line-to-line voltage divided by 1.732, so 208 / 1.732 ≈ 120 V.

Question 112: Which method of opening a steam valve to a cold system is correct?

Open it quickly to heat the piping faster
Open it slowly to warm the line and drain condensate, preventing water hammer (Correct answer)
Open it only after closing all traps
Open it fully, then close it partway

Correct answer: Open it slowly to warm the line and drain condensate, preventing water hammer

Slow warm-up lets condensate drain and avoids dangerous water hammer.

Question 113: Supply air temperature reset in a VAV system during mild weather saves energy mainly by:

Reducing reheat energy at terminal units (Correct answer)
Increasing fan static pressure
Raising the outdoor air ratio to 100%
Eliminating the need for economizers

Correct answer: Reducing reheat energy at terminal units

Raising supply air temperature when loads are light reduces both overcooling and the reheat needed to correct it.

Question 114: A thermostatic expansion valve (TXV) modulates refrigerant flow to maintain a constant:

Evaporator superheat (Correct answer)
Oil pressure
Condenser subcooling
Discharge pressure

Correct answer: Evaporator superheat

The TXV's sensing bulb on the suction line controls superheat.

Question 115: What is the correct way to verify the accuracy of a BAS space temperature sensor?

Compare its reading with a calibrated reference instrument at the same location (Correct answer)
Compare it with the thermostat setpoint
Check that the sensor's color matches the wall
Look at the outside air temperature reading

Correct answer: Compare its reading with a calibrated reference instrument at the same location

Calibration means comparing the sensor with a traceable reference instrument placed at the same point and correcting any offset.

Question 116: Before closing a work order, what should a quality inspection confirm?

The technician recorded their break times
The parts invoice has been paid
The equipment has been tagged out permanently
The work is complete, the equipment runs correctly, and the details are documented (Correct answer)

Correct answer: The work is complete, the equipment runs correctly, and the details are documented

Closeout should confirm the repair fixed the problem, the system runs normally, and the work history is recorded.

Question 117: Which type of HVAC system allows individual control of different building zones?

Split system
Packaged unit
Zoned system (Correct answer)
Centralized system

Correct answer: Zoned system

Zoned HVAC systems divide spaces into areas that can be controlled independently, increasing energy efficiency and comfort.

Question 118: Which group of tasks is most typical of a quarterly air handler PM checklist?

Checking belts, lubricating bearings as specified, inspecting filters and drain pans (Correct answer)
Replacing the whole ductwork system
Recharging the building's fire extinguishers
Rewinding the motor and replacing the fan wheel

Correct answer: Checking belts, lubricating bearings as specified, inspecting filters and drain pans

Routine AHU PM centers on drives, bearings, filters, coils, and condensate drain pans.

Question 119: Under NFPA 70E, what document or label tells a worker the incident energy and required PPE before working on an energized panel?

Panel schedule directory
Certificate of occupancy
Arc flash warning label (Correct answer)
UL listing mark

Correct answer: Arc flash warning label

Arc flash labels display incident energy or PPE category and the arc flash boundary for that equipment.

Question 120: Utility power factor penalties can be reduced by installing:

Larger transformers
Capacitor banks for power factor correction (Correct answer)
Incandescent lighting
Additional induction motors

Correct answer: Capacitor banks for power factor correction

Capacitors offset inductive reactive power, which raises the power factor and avoids utility penalties.

BOC Building Operator Certification

The BOC Certification Exam is a nationally recognized credential validating knowledge of energy-efficient building operations and maintenance for facilities professionals. It covers building systems maintenance, energy management, technical/administrative duties, and indoor environmental quality.

120

Questions

180 min

Time Limit

67%

To Pass

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