InterNACHI Electrical Systems and Safety 2 — Questions and Answers
Question 1: What is the minimum clearance required between the top of a residential electrical panel and the ceiling?
- 3 feet
- 6 feet (Correct answer)
- 6.5 feet
- No clearance required
Correct answer: 6 feet
NEC requires at least 6 feet of headroom clearance above electrical panels to allow safe access for work.
Question 2: Which wire color in a standard 120V household circuit indicates the neutral conductor?
- Black
- Red
- White (Correct answer)
- Green
Correct answer: White
White wires are the neutral conductors in standard 120V household circuits, carrying current back to the panel.
Question 3: An inspector finds that a bathroom outlet is not GFCI-protected but is within 6 feet of a sink. What should be noted?
- This is acceptable if the circuit is 15-amp
- This is a safety deficiency requiring correction (Correct answer)
- GFCI is only required within 3 feet of a sink
- GFCI is optional in bathrooms built before 2000
Correct answer: This is a safety deficiency requiring correction
All bathroom outlets require GFCI protection regardless of distance from a water source, per current NEC requirements.
Question 4: What does the term 'double-tapping' refer to in electrical panel inspections?
- Installing two panels in series
- Connecting two conductors to a single breaker terminal (Correct answer)
- Using two ground wires on one breaker
- Wiring a circuit with two hot wires only
Correct answer: Connecting two conductors to a single breaker terminal
Double-tapping occurs when two wires are connected to a single breaker terminal, which is a defect unless the breaker is rated for it.
Question 5: Which of the following best describes a 'floating neutral' condition in an electrical panel?
- A neutral wire connected to a grounding electrode
- A neutral bus that is bonded to the ground bus in a sub-panel
- A neutral bus not properly bonded, causing voltage imbalance (Correct answer)
- A neutral wire insulated with white tape
Correct answer: A neutral bus not properly bonded, causing voltage imbalance
A floating neutral occurs when the neutral is not properly connected, which can cause dangerous voltage imbalances on 240V circuits.
Question 6: When inspecting older homes, what type of wiring is characterized by two conductors insulated and wrapped together in a cloth-like jacket without a ground wire?
- Conduit wiring
- Knob-and-tube wiring (Correct answer)
- Aluminum branch circuit wiring
- Non-metallic sheathed cable (NM)
Correct answer: Knob-and-tube wiring
Knob-and-tube wiring uses separate hot and neutral conductors supported by ceramic knobs and tubes, with no equipment ground.
Question 7: What is the primary safety concern when a home inspector discovers aluminum branch circuit wiring connected to a standard copper-rated outlet?
- Aluminum corrodes faster in humid climates
- Aluminum expands and contracts differently than copper, causing loose connections and fire risk (Correct answer)
- Aluminum wiring cannot carry sufficient amperage
- Aluminum wiring is not approved for residential use under any code
Correct answer: Aluminum expands and contracts differently than copper, causing loose connections and fire risk
Aluminum expands and contracts at a different rate than copper, causing connections to loosen over time, creating heat and fire hazards.
InterNACHI Electrical Systems and Safety 2
What is the minimum clearance required between the top of a residential electrical panel and the ceiling?