Home Inspector Electrical System Safety Hazards Questions and Answers — Questions and Answers
Question 1: During an inspection of a home built in 1968, a home inspector identifies solid strand aluminum branch circuit wiring. Which of the following represents the MOST significant hazard associated with this type of wiring?
- It is incompatible with modern high-amperage appliances.
- The wiring is prone to breaking during installation.
- Connections can loosen over time, leading to overheating and arcing. (Correct answer)
- Aluminum wiring emits a gas that can degrade insulation.
Correct answer: Connections can loosen over time, leading to overheating and arcing.
Solid strand aluminum wiring has a higher coefficient of thermal expansion than copper. This property, known as "cold creep," causes the wire to expand and contract more with temperature changes. Over time, this can lead to loose connections at terminals (outlets, switches, breakers), which increases resistance, causes overheating, and creates a serious fire hazard from arcing.
Question 2: A home inspector finds a service panel with circuit breakers labeled "FPE Stab-Lok." This finding should be reported as a significant safety concern primarily because these panels are known for which of the following?
- A high rate of manufacturing defects causing breakers to fail to trip. (Correct answer)
- Containing asbestos insulation, which is a respiratory hazard.
- Being susceptible to water intrusion due to poor case design.
- Using an outdated grounding method that is no longer code-compliant.
Correct answer: A high rate of manufacturing defects causing breakers to fail to trip.
Federal Pacific Electric (FPE) Stab-Lok panels and breakers have a well-documented history of failing to trip during an overcurrent or short-circuit event. This failure can lead to wiring overheating, creating a substantial risk of fire. Independent testing has shown a high failure rate for these breakers, making their presence a major safety hazard.
Question 3: Which of the following describes a key safety hazard associated with knob-and-tube wiring?
- The porcelain knobs are prone to shattering with age.
- The system inherently lacks a grounding conductor. (Correct answer)
- It can only be used with low-voltage lighting systems.
- The copper conductors are typically undersized for any load.
Correct answer: The system inherently lacks a grounding conductor.
Knob-and-tube (K&T) wiring systems were designed and installed before equipment grounding conductors were required. This system consists of only a hot and a neutral wire. The lack of a ground wire means there is no safe path for fault current to travel, which increases the risk of electric shock and fire.
Question 4: While inspecting a recently remodeled kitchen, a home inspector notes that a new 125-volt, 15-amp receptacle is installed 18 inches from the edge of the kitchen sink to serve a countertop appliance. Which safety device is MOST likely required for this receptacle?
- A surge protector.
- An Arc-Fault Circuit Interrupter (AFCI).
- A Ground-Fault Circuit Interrupter (GFCI). (Correct answer)
- A dedicated 20-amp circuit.
Correct answer: A Ground-Fault Circuit Interrupter (GFCI).
The National Electrical Code (NEC) requires Ground-Fault Circuit Interrupter (GFCI) protection for virtually all receptacles serving kitchen countertops in dwelling units. GFCIs are designed to protect people from electric shock by quickly shutting off power if they detect an imbalance in the current, which can occur if electricity finds a path to ground through a person, especially in potentially wet locations like kitchens.
Question 5: An inspector observes two conductors terminated under a single screw on a circuit breaker that is not designed for this purpose. This defect is commonly referred to as a:
- Series fault
- Phase imbalance
- Double-tap (Correct answer)
- Cross connection
Correct answer: Double-tap
A "double-tap" or "double-lug" occurs when two or more conductors are connected to a terminal or circuit breaker that is only rated for one. This is a common defect that can lead to a loose connection, overheating, arcing, and a potential fire hazard because the screw cannot apply proper pressure to both wires.
Question 6: What is the primary function of an Arc-Fault Circuit Interrupter (AFCI) device?
- To protect occupants from shock in wet locations.
- To de-energize a circuit when it detects a dangerous arcing condition. (Correct answer)
- To protect sensitive electronics from voltage surges.
- To prevent the overloading of a circuit from too many appliances.
Correct answer: To de-energize a circuit when it detects a dangerous arcing condition.
An Arc-Fault Circuit Interrupter (AFCI) is a safety device designed to detect the unique characteristics of a dangerous electrical arc and de-energize the circuit before the arc can cause a fire. Arcs can be caused by damaged wiring, loose connections, or other faults that standard circuit breakers may not detect.
Home Inspector Electrical System Safety Hazards Questions and Answers
During an inspection of a home built in 1968, a home inspector identifies solid strand aluminum branch circuit wiring.
Which of the following represents the MOST significant hazard associated with this type of wiring?