What is a visible sign of deterioration in knob-and-tube wiring?

• A. Cracked insulation and exposed wires
• B. Consistent electrical performance
• C. Low energy consumption readings
• D. No signs of wear at all

Answer: (A)

A visible sign of deterioration in knob-and-tube wiring is indeed cracked insulation and exposed wires. Knob-and-tube systems were widely used in the early to mid-20th century for residential electrical wiring. Over time, the insulation material, often made from rubber or cloth, can degrade due to factors such as age, heat, and exposure to moisture. This deterioration can lead to cracks, which expose the conductive copper wires.

Exposed wires pose a serious safety risk, as they can lead to electrical shorts, sparks, or even fires. Additionally, the presence of cracks in the insulation can compromise the wiring's ability to safely contain electrical current, further increasing the risk of electrical hazards in the home.

The other options reflect scenarios that would not indicate deterioration; for instance, consistent electrical performance, low energy consumption readings, and no signs of wear at all suggest that the wiring is functioning optimally. However, these are not indicators of visible deterioration, which is critical to identify for safety and compliance standards in residential electrical inspections.