HVAC Code Compliance 4 — Questions and Answers
Question 1: Under the National Electrical Code (NEC) Article 440, what is the purpose of the branch-circuit short-circuit and ground-fault protective device for a hermetic refrigerant motor-compressor?
- Provides overload protection only
- Protects the branch circuit conductors and equipment from short-circuit and ground-fault conditions (Correct answer)
- Controls compressor cycling on thermostat demand
- Prevents voltage spikes from the power grid
Correct answer: Protects the branch circuit conductors and equipment from short-circuit and ground-fault conditions
NEC 440 requires a branch-circuit protective device sized to protect conductors and equipment from short-circuit and ground-fault currents, separate from overload protection.
Question 2: Per the International Mechanical Code, when must a carbon monoxide alarm be installed in a dwelling that has a fuel-burning appliance?
- Only if the appliance is in a bedroom
- Outside each sleeping area in the immediate vicinity of bedrooms (Correct answer)
- In the mechanical room only
- Only in basements where appliances are installed
Correct answer: Outside each sleeping area in the immediate vicinity of bedrooms
The IMC and IRC require CO alarms to be installed outside each sleeping area in the immediate vicinity of bedrooms in dwellings with fuel-burning appliances.
Question 3: Which ASHRAE standard specifically addresses the safety of refrigeration systems and specifies refrigerant classifications like A1, A2L, and B2?
- ASHRAE 62.1
- ASHRAE 90.1
- ASHRAE 34 (Correct answer)
- ASHRAE 15
Correct answer: ASHRAE 34
ASHRAE Standard 34 establishes a refrigerant designation system and safety classification, grouping refrigerants by toxicity (A/B) and flammability (1/2L/2/3).
Question 4: Per the International Fuel Gas Code, what is the maximum pressure drop allowed in a low-pressure natural gas piping system from the meter to the appliance?
- 0.1 inch W.C.
- 0.3 inch W.C.
- 0.5 inch W.C. (Correct answer)
- 1.0 inch W.C.
Correct answer: 0.5 inch W.C.
The IFGC allows a maximum pressure drop of 0.5 inch water column in low-pressure gas piping systems to ensure adequate pressure at appliances.
Question 5: Under the International Mechanical Code, what ventilation requirement applies to a commercial kitchen exhaust hood?
- Exhaust must equal supply air volume
- Makeup air must be provided at 80-100% of exhaust volume (Correct answer)
- No makeup air is required if exhaust is under 1,000 CFM
- Makeup air must be heated to room temperature before introduction
Correct answer: Makeup air must be provided at 80-100% of exhaust volume
The IMC requires that makeup air be provided at approximately 80 to 100 percent of the exhaust volume to maintain proper pressure balance in commercial kitchens.
Question 6: When installing a split-system air conditioner, the NEC requires a disconnect switch that is within sight and within how many feet of the outdoor condensing unit?
- 10 feet
- 25 feet
- 50 feet (Correct answer)
- 100 feet
Correct answer: 50 feet
NEC 440.14 requires a disconnect means to be within sight of the air-conditioning equipment and within 50 feet for safety during service and maintenance.
Question 7: According to ASHRAE 90.1, what is required of HVAC systems with a cooling capacity of 65,000 BTU/hr or more in commercial buildings?
- Manual-only controls
- Economizer capability or exception compliance (Correct answer)
- Minimum two-stage compressors
- Separate metering for each zone
Correct answer: Economizer capability or exception compliance
ASHRAE 90.1 requires air-side or water-side economizers on cooling systems at or above 65,000 BTU/hr capacity, unless an approved exception applies.
HVAC Code Compliance 4
Under the National Electrical Code (NEC) Article 440, what is the purpose of the branch-circuit short-circuit and ground-fault protective device for a hermetic refrigerant motor-compressor?