Home Inspector Test Home Inspector Electrical System Safety Hazards 5 — Questions and Answers
Question 1: What is the hazard of using a 25-amp fuse in a fuse box to replace a repeatedly blowing 15-amp fuse?
- The circuit will trip more frequently with a larger fuse
- The overcurrent protection is defeated, allowing the 15-amp wire to overheat and cause a fire (Correct answer)
- Larger fuses reduce voltage to appliances on the circuit
- There is no hazard as long as the fuse is the correct physical size
Correct answer: The overcurrent protection is defeated, allowing the 15-amp wire to overheat and cause a fire
Over-fusing bypasses the wire's protection; the fuse will not blow even when the wire carries dangerous levels of current.
Question 2: An inspector finds NM cable (Romex) run through a metal stud without a plastic bushing or grommet. What is the hazard?
- Metal studs reduce the cable's ampacity by 50%
- Sharp metal edges can cut into the cable insulation over time, causing a short or arc fault (Correct answer)
- NM cable cannot be used in metal-framed walls at all
- The cable will corrode where it contacts metal
Correct answer: Sharp metal edges can cut into the cable insulation over time, causing a short or arc fault
Metal stud knockouts have sharp edges that can abrade Romex insulation with building movement, eventually causing a fault.
Question 3: What does the inspector look for to identify a 'split bus' panel, and why can it be confusing?
- A panel where the bus bar is physically broken, indicating damage
- A panel with two separate bus sections — one fed by a 240V main and one by large breakers — with no single main disconnect, requiring up to six breaker operations to shut off all power (Correct answer)
- A panel that has been modified to add a sub-panel inside
- A panel where breakers are installed horizontally instead of vertically
Correct answer: A panel with two separate bus sections — one fed by a 240V main and one by large breakers — with no single main disconnect, requiring up to six breaker operations to shut off all power
Split-bus panels predate the single main disconnect rule; inspectors must identify them because multiple breaker operations are needed to de-energize the panel.
Question 4: A garage has a 240V outlet with no GFCI protection. Under current NEC requirements, what should be reported?
- 240V outlets in garages are exempt from GFCI requirements
- GFCI protection is required for all 15- and 20-amp, 125V and 250V receptacles in garages (Correct answer)
- Only 120V outlets in garages require GFCI protection
- GFCI is only required if the garage has a water source
Correct answer: GFCI protection is required for all 15- and 20-amp, 125V and 250V receptacles in garages
Recent NEC editions expanded GFCI requirements to include 250V receptacles in garages, not just standard 120V outlets.
Question 5: What is the concern when an inspector finds multiple circuits sharing a single neutral conductor (a multi-wire branch circuit) without a handle-tied breaker?
- Shared neutrals always cause voltage imbalance
- If one hot leg is de-energized alone, the neutral remains live, creating a shock hazard during servicing (Correct answer)
- Shared neutrals reduce circuit ampacity by half
- Multi-wire branch circuits are prohibited by NEC in all cases
Correct answer: If one hot leg is de-energized alone, the neutral remains live, creating a shock hazard during servicing
Without a handle tie, one breaker can be turned off while the shared neutral remains energized from the other circuit, shocking anyone who believes the wire is safe to handle.
Question 6: An inspector finds an outdoor receptacle with a cover that is only rated for 'closed while in use.' What is inadequate about this?
- Outdoor outlets do not need covers if they are under an overhang
- Current NEC requires 'in-use' (bubble) covers that protect the outlet even while a cord is plugged in (Correct answer)
- Closed-while-in-use covers meet all current NEC requirements
- Only metal covers are acceptable for outdoor outlets
Correct answer: Current NEC requires 'in-use' (bubble) covers that protect the outlet even while a cord is plugged in
NEC now requires in-use covers that maintain a weatherproof seal even with a cord plugged in, since flat covers leave the outlet exposed to moisture during use.
Question 7: What hazard does improperly rated wire insulation in a high-temperature location (such as inside a luminaire) present?
- High temperature reduces wire resistance, increasing power draw
- Insulation can melt or char, causing a short circuit or fire within the fixture (Correct answer)
- Wires in luminaires always use the same insulation as branch circuits
- High heat only affects aluminum wiring, not copper
Correct answer: Insulation can melt or char, causing a short circuit or fire within the fixture
Using standard insulation rated at 60°C in fixtures that reach higher temperatures causes insulation breakdown, leading to shorts and potential fire.
Home Inspector Test Home Inspector Electrical System Safety Hazards 5
What is the hazard of using a 25-amp fuse in a fuse box to replace a repeatedly blowing 15-amp fuse?