Final answer:
The most common reasons for the replacement of knob-and-tube wiring are the breakdown of cloth covering, being buried in thermal insulation, and homeowner splices and repairs. Option D is the correct answer.
Step-by-step explanation:
Knob-and-tube wiring is an outdated electrical system that was commonly used in houses built before the 1930s. The most common reason for its replacement is the breakdown of the cloth covering that provides insulation. Over time, the cloth covering can wear out, become brittle, and expose wires, increasing the risk of electrical shocks and fire hazards.
Another reason for replacement is when knob-and-tube wiring is buried in thermal insulation, such as blown-in insulation or spray foam. This can cause the wiring to overheat, leading to electrical failures and potential fire hazards.
Lastly, homeowner splices and repairs can also contribute to the need for replacement. Since knob-and-tube wiring is an older system, it may require repairs or modifications over time. However, these repairs by homeowners may not follow proper electrical codes and can compromise the safety of the wiring system.
In conclusion, the most common reasons for the replacement of knob-and-tube wiring are the breakdown of cloth covering, being buried in thermal insulation, and homeowner splices and repairs.