Home Inspector Test Home Inspector Electrical System Safety Hazards 3 — Questions and Answers
Question 1: Why are knob-and-tube wiring systems particularly hazardous when insulation has been added to the attic?
- Insulation blocks radio frequency interference from the wiring
- Knob-and-tube relies on open-air cooling; insulation traps heat and can cause fires (Correct answer)
- The knobs deteriorate when exposed to fiberglass
- Insulation causes the wiring to corrode faster
Correct answer: Knob-and-tube relies on open-air cooling; insulation traps heat and can cause fires
Knob-and-tube wiring was designed to dissipate heat into free air; surrounding it with insulation removes this cooling and can cause overheating.
Question 2: An inspector notices the service entrance cable insulation is cracked and brittle at the weatherhead. What is the primary risk?
- Water intrusion into the panel causing corrosion over years
- Exposed energized conductors that can arc, spark, or electrocute utility workers and occupants (Correct answer)
- Reduced amperage capacity of the service
- Higher electric bills due to energy loss
Correct answer: Exposed energized conductors that can arc, spark, or electrocute utility workers and occupants
Service entrance conductors are often not protected by any breaker; exposed live wires at the weatherhead represent an immediate electrocution and fire hazard.
Question 3: What hazard is created when an electrical panel is located inside a clothes closet?
- Clothing and stored materials can be ignited by arcing or heat from the panel (Correct answer)
- The panel cannot be inspected properly due to darkness
- Closet humidity will cause the panel to rust immediately
- NEC prohibits panels in closets only if they face the wall
Correct answer: Clothing and stored materials can be ignited by arcing or heat from the panel
NEC prohibits panels in clothes closets because combustible materials stored there create a fire risk from panel arcing or heat.
Question 4: A home has a 60-amp service with a modern electric range, HVAC, and electric water heater. What concern should the inspector note?
- 60-amp service is adequate for all residential loads
- The service is likely undersized, creating overload risk and nuisance tripping (Correct answer)
- Electric appliances require only 30-amp service
- The main breaker will automatically upgrade to handle the load
Correct answer: The service is likely undersized, creating overload risk and nuisance tripping
Modern high-draw appliances typically require 100- to 200-amp service; 60-amp service is undersized and creates overload and fire risk.
Question 5: What is a 'bootleg ground' and why does it fail to provide adequate protection?
- A ground wire added to an older panel without a ground bus
- A jumper between the neutral and ground slots of an outlet, which does not provide a true equipment ground path (Correct answer)
- A ground rod installed without proper burial depth
- An extra ground wire run outside the conduit
Correct answer: A jumper between the neutral and ground slots of an outlet, which does not provide a true equipment ground path
Bootleg grounds fool testers into reading 'correct' but carry no fault current safely to earth, leaving equipment and users unprotected.
Question 6: Why is it a hazard when junction boxes are left without covers inside a wall cavity?
- Uncovered boxes allow vermin to nest in the panel
- Exposed wire connections can arc and ignite nearby combustible framing (Correct answer)
- The wires will lose voltage without a cover
- Open boxes reduce circuit ampacity by 10%
Correct answer: Exposed wire connections can arc and ignite nearby combustible framing
Covers contain any arcing or heat from connections; without them, a failing splice can directly ignite wood framing.
Question 7: An inspector finds extension cords used as permanent wiring under carpet in a living room. What hazards exist?
- Extension cords are rated for permanent use if they are heavy-duty
- Foot traffic damages insulation, and trapped heat under carpet can ignite fibers (Correct answer)
- The only issue is that extension cords are unsightly
- Extension cords under carpet are acceptable if plugged into a GFCI outlet
Correct answer: Foot traffic damages insulation, and trapped heat under carpet can ignite fibers
Extension cords are not rated for permanent or concealed use; abrasion and heat buildup under carpet create arcing and fire hazards.
Home Inspector Test Home Inspector Electrical System Safety Hazards 3
Why are knob-and-tube wiring systems particularly hazardous when insulation has been added to the attic?