NHIE Electrical Systems 2 — Questions and Answers
Question 1: A home inspector finds aluminum wiring connected to a standard copper-rated outlet. What is the primary concern?
- Aluminum is too rigid to make reliable connections
- Aluminum and copper expand at different rates, causing loose connections and fire risk (Correct answer)
- Aluminum wiring requires larger gauge than copper
- Aluminum wiring is not permitted in residential construction
Correct answer: Aluminum and copper expand at different rates, causing loose connections and fire risk
Dissimilar metal expansion rates cause connections to loosen over time, creating arcing and fire hazards.
Question 2: What is the minimum clearance required between the top of a residential service panel and the ceiling?
- 24 inches
- 36 inches (Correct answer)
- 48 inches
- No clearance required if the panel face is accessible
Correct answer: 36 inches
NEC requires 36 inches of headroom clearance above electrical equipment requiring examination or maintenance.
Question 3: A home inspector observes double-tapped breakers in a panel. Which scenario is acceptable?
- Any two 15-amp circuits can share one breaker
- Only if both wires are the same gauge
- Only on breakers specifically listed and labeled for two conductors (Correct answer)
- Double-tapping is never acceptable in any panel
Correct answer: Only on breakers specifically listed and labeled for two conductors
Some breakers are UL-listed to accept two conductors; this is noted in the manufacturer's listing.
Question 4: What does a GFCI receptacle protect against that a standard circuit breaker does not?
- Overloads caused by too many appliances
- Ground faults where current takes an unintended path through a person (Correct answer)
- Short circuits between hot and neutral conductors
- Voltage surges from lightning strikes
Correct answer: Ground faults where current takes an unintended path through a person
GFCI devices trip when they detect as little as 4–6 mA of current imbalance, protecting against electrocution.
Question 5: During an inspection, a home inspector notes that the grounding electrode conductor is spliced. What should the inspector report?
- Splices are permitted if made with approved connectors
- The grounding electrode conductor must be continuous without splices (Correct answer)
- Splices are acceptable only if inside a junction box
- Splices are permitted only in the panel enclosure
Correct answer: The grounding electrode conductor must be continuous without splices
NEC requires the grounding electrode conductor to run without splices from the panel to the grounding electrode.
Question 6: What is the purpose of the main bonding jumper in a service panel?
- It connects the neutral bar to the grounding bar in the main panel (Correct answer)
- It provides a path for surge current to the utility transformer
- It connects the panel enclosure to the grounding electrode
- It separates the grounded and grounding conductors in subpanels
Correct answer: It connects the neutral bar to the grounding bar in the main panel
The main bonding jumper connects the neutral (grounded) conductor to the equipment grounding conductor at the service entrance.
Question 7: A home inspector finds knob-and-tube wiring in an attic that has been buried under blown-in insulation. Why is this a concern?
- Knob-and-tube wiring is not approved for attic locations
- Knob-and-tube relies on air circulation for cooling and insulation removes this (Correct answer)
- Insulation adds too much weight to the old wire insulation
- The wiring must be visible for fire code compliance
Correct answer: Knob-and-tube relies on air circulation for cooling and insulation removes this
Knob-and-tube wiring was designed to dissipate heat through open air; burying it in insulation can cause overheating and fire.
NHIE Electrical Systems 2
A home inspector finds aluminum wiring connected to a standard copper-rated outlet.
What is the primary concern?