General Contractor License Mechanical, Electrical, and Plumbing Systems

Question 1

Under the National Electrical Code (NEC), what is the minimum burial depth for a residential underground feeder (UF) cable installed without conduit?

Accepted Answer

18 inches

Answer

6 inches

Answer

12 inches

Answer

24 inches

Question 2

Which type of pipe is most commonly required by code for natural gas supply lines inside a residential structure?

Accepted Answer

Black steel pipe

Answer

PVC schedule 40

Answer

CPVC

Answer

PEX tubing

Question 3

According to the IRC, what is the required minimum headroom clearance for a residential stairway?

Accepted Answer

6 feet 8 inches

Answer

6 feet 4 inches

Answer

6 feet 6 inches

Answer

7 feet 0 inches

Question 4

When sizing a residential water heater, which factor is the MOST important determinant of required capacity?

Accepted Answer

First Hour Rating (FHR)

Answer

Tank color and insulation rating

Answer

BTU input rating only

Answer

Tank diameter

Question 5

In a residential electrical panel, a double-pole 240V breaker that trips on only one leg is an indication of what condition?

Accepted Answer

A failed breaker requiring replacement

Answer

Overload on the neutral wire

Answer

Proper load balancing

Answer

A ground fault only

Question 6

Which plumbing fitting is required at the base of a soil stack where it transitions from vertical to horizontal?

Accepted Answer

Long-sweep 1/4 bend

Answer

90-degree elbow

Answer

Sanitary tee

Answer

Coupling