CBC Mechanical, Electrical & Plumbing (MEP) Systems 3

Question 1

What is the standard residential electrical service voltage in the United States?

Accepted Answer

120/240 volts, single-phase

Answer

Standard US residential service provides 120/240-volt single-phase power, delivering 120V for outlets and lighting and 240V for large appliances.

Question 2

Which pipe material is most commonly used for residential drain, waste, and vent (DWV) systems in the US?

Accepted Answer

PVC Schedule 40

Answer

PVC Schedule 40 is the dominant DWV pipe material in residential construction due to its low cost, ease of installation, and corrosion resistance.

Question 3

What is the minimum wire gauge (AWG) required for a 20-amp branch circuit per the NEC?

Accepted Answer

12 AWG

Answer

The NEC requires 12 AWG copper conductors for 20-amp circuits; using 14 AWG (rated 15 amps) on a 20-amp breaker creates an overheating and fire risk.

Question 4

In a split-system air conditioner, which component is located outdoors?

Accepted Answer

Condenser unit

Answer

The condenser unit, containing the compressor, condenser coil, and condenser fan, is installed outdoors to reject heat absorbed from inside the building.

Question 5

What is the function of a condensate drain in an air conditioning system?

Accepted Answer

To remove moisture collected by the evaporator coil during cooling

Answer

During cooling, moisture from indoor air condenses on the evaporator coil; the condensate drain removes this water to prevent overflow and property damage.

(CBC) Certified Building Contractor Practice Test

(CBC) Certified Building Contractor Practice Test

CBC Mechanical, Electrical & Plumbing (MEP) Systems 3