NCCER Basic Electrical & Plumbing 2 — Questions and Answers
Question 1: What is the purpose of a GFCI outlet in a bathroom?
- To provide extra amperage for hair dryers
- To protect against electric shock near water sources (Correct answer)
- To reduce voltage for sensitive electronics
- To allow two devices to share one circuit
Correct answer: To protect against electric shock near water sources
GFCI (Ground Fault Circuit Interrupter) outlets detect current leakage and trip within milliseconds to prevent electric shock near water.
Question 2: A homeowner notices their toilet runs continuously after flushing. What is the most likely cause?
- Clogged drain line
- Faulty flapper valve not sealing properly (Correct answer)
- Low water pressure from the main supply
- Cracked toilet bowl
Correct answer: Faulty flapper valve not sealing properly
A worn or misaligned flapper valve fails to seal the flush valve seat, allowing water to continuously flow from the tank into the bowl.
Question 3: When running new electrical wire through a wall, what is the minimum bend radius for NM cable (Romex)?
- No bend radius requirement for NM cable
- 5 times the diameter of the cable (Correct answer)
- No sharper than a 90-degree angle
- Must remain perfectly straight
Correct answer: 5 times the diameter of the cable
NM cable must be bent no tighter than 5 times the cable diameter to prevent damage to the conductors and insulation.
Question 4: Which pipe fitting is used to join two pipes of different diameters in a plumbing system?
- Coupling
- Elbow
- Reducer (Correct answer)
- Tee
Correct answer: Reducer
A reducer (or reducing coupling) connects pipes of two different sizes while maintaining flow in the same direction.
Question 5: What does the term 'voltage drop' mean in an electrical circuit?
- A sudden power outage in the building
- Reduction in voltage along a conductor due to resistance (Correct answer)
- The difference between 120V and 240V service
- A short circuit condition
Correct answer: Reduction in voltage along a conductor due to resistance
Voltage drop is the decrease in electrical potential along a conductor caused by the conductor's resistance, which can cause lights to dim or motors to run poorly.
Question 6: What is the correct slope (grade) for a residential drain pipe to ensure proper drainage?
- 1/8 inch per foot
- 1/4 inch per foot (Correct answer)
- 1/2 inch per foot
- 1 inch per foot
Correct answer: 1/4 inch per foot
Residential drain pipes should slope 1/4 inch per foot (2%) to allow waste to flow while keeping enough water to carry solids.
Question 7: In electrical work, what color is typically used for the neutral wire in a standard 120V residential circuit?
- Black
- Green
- White (Correct answer)
- Red
Correct answer: White
White (or gray) wire is the neutral conductor in residential wiring, completing the circuit back to the panel's neutral bus bar.
NCCER Basic Electrical & Plumbing 2
What is the purpose of a GFCI outlet in a bathroom?