General Contractor License Mechanical, Electrical, and Plumbing Systems 2 — Questions and Answers
Question 1: Under ASHRAE 62.2, which ventilation method is considered the minimum standard for indoor air quality in new residential construction?
- Spot exhaust fans only
- Whole-house mechanical ventilation (Correct answer)
- Opening windows daily
- Kitchen exhaust recirculation only
Correct answer: Whole-house mechanical ventilation
ASHRAE 62.2 requires whole-house mechanical ventilation in new residential construction to maintain acceptable indoor air quality continuously.
Question 2: A GFCI outlet must be installed in which of the following locations in a residential bathroom?
- Only within 3 feet of the sink
- Any outlet within 6 feet of a water source
- All outlets regardless of location (Correct answer)
- Only near the bathtub or shower
Correct answer: All outlets regardless of location
NEC requires GFCI protection for ALL receptacle outlets in bathrooms, regardless of their distance from water sources.
Question 3: What is the purpose of an air admittance valve (AAV) in a plumbing drain-waste-vent system?
- Increase water pressure at fixtures
- Allow air into drain lines without extending vent pipes through the roof (Correct answer)
- Prevent backflow from the sewer
- Regulate hot water temperature
Correct answer: Allow air into drain lines without extending vent pipes through the roof
An AAV allows air to enter the drain system to equalize pressure and prevent siphoning of trap seals without requiring a full vent pipe penetration through the roof.
Question 4: According to the IRC, what is the maximum distance a P-trap can be located from its fixture drain outlet (trap arm length)?
- 18 inches
- 24 inches (Correct answer)
- 36 inches
- 48 inches
Correct answer: 24 inches
The IRC limits trap arm length (distance from the trap weir to the vent) to 24 inches for a 1.5-inch diameter drain to ensure adequate drainage and trap protection.
Question 5: Which electrical conductor color is designated as the grounding conductor per NEC in the United States?
- White or gray
- Red
- Green or bare copper (Correct answer)
- Black
Correct answer: Green or bare copper
NEC designates green insulation or bare copper wire as the equipment grounding conductor in branch circuit wiring.
Question 6: When installing forced-air HVAC ductwork, what is the primary reason supply registers and return air grilles should NOT be located in the same wall cavity?
- It increases duct leakage rates
- Short-cycling occurs when conditioned air is immediately pulled back to the return (Correct answer)
- It violates insulation requirements
- It causes condensation on walls
Correct answer: Short-cycling occurs when conditioned air is immediately pulled back to the return
Placing supply and return air in the same cavity causes short-cycling, where conditioned air is pulled back to the return before reaching the occupied space, reducing system efficiency.
General Contractor License Mechanical, Electrical, and Plumbing Systems 2
Under ASHRAE 62.2, which ventilation method is considered the minimum standard for indoor air quality in new residential construction?