NCCER Electrical 2 — Questions and Answers
Question 1: In standard US 120V residential wiring, which wire is the ungrounded (hot) conductor?
- White wire
- Green wire
- Black wire (Correct answer)
- Bare copper wire
Correct answer: Black wire
The black wire is the ungrounded (hot) conductor in standard US residential wiring, carrying current from the panel to the load.
Question 2: What is the maximum conduit fill percentage allowed by the NEC when three or more conductors are installed?
- 25%
- 40% (Correct answer)
- 53%
- 60%
Correct answer: 40%
The NEC limits conduit fill to 40% when three or more conductors are installed to prevent heat buildup and conductor damage.
Question 3: Which type of conduit is approved for outdoor use, wet locations, and direct burial?
- EMT (Electrical Metallic Tubing)
- Rigid Metal Conduit (RMC) (Correct answer)
- Flexible Metal Conduit (FMC)
- ENT (Electrical Non-metallic Tubing)
Correct answer: Rigid Metal Conduit (RMC)
Rigid Metal Conduit (RMC) is the most durable conduit type and is approved for outdoor, wet, and direct burial applications.
Question 4: In a standard 240V residential circuit, what color is typically used for the second hot conductor?
- Black
- White
- Red (Correct answer)
- Green
Correct answer: Red
In a 240V circuit, the second ungrounded (hot) conductor is typically red, while the first hot conductor is black.
Question 5: What does AWG stand for in the context of electrical wire sizing?
- American Wire Gauge (Correct answer)
- Amperage Wire Grade
- Approved Wiring Guide
- American Wiring Group
Correct answer: American Wire Gauge
AWG stands for American Wire Gauge, the standard US system for specifying wire diameter where smaller numbers indicate larger wire sizes.
Question 6: What is the current-carrying capacity (ampacity) of a 12 AWG copper conductor under standard conditions?
- 15 amperes
- 20 amperes (Correct answer)
- 30 amperes
- 40 amperes
Correct answer: 20 amperes
A 12 AWG copper conductor has an ampacity of 20 amperes as listed in NEC Table 310.12 under standard conditions.
Question 7: What is the primary purpose of the neutral (white) wire in a standard 120V circuit?
- To carry fault current to ground
- To supply additional power to the load
- To complete the circuit by returning current to the source (Correct answer)
- To protect against voltage surges
Correct answer: To complete the circuit by returning current to the source
The neutral wire provides the return path for current from the load back to the source (electrical panel), completing the circuit.
NCCER Electrical 2
In standard US 120V residential wiring, which wire is the ungrounded (hot) conductor?