What is “knob-and-tube” wiring, and why is it significant?

Knob-and-tube wiring is an early method of electrical wiring installation that was common in homes built in the late 19th and early 20th centuries. This wiring system consists of insulated copper conductors that are run through ceramic knobs and tubes, designed to hold the wires in place and protect them from damage.

The significance of knob-and-tube wiring lies in its status as an outdated electrical system that can pose safety risks today. Over the years, it has been recognized that this type of wiring has several drawbacks, including a lack of grounding, which can expose homes to electrical shocks and fire hazards. Additionally, knob-and-tube systems were not designed to handle the electrical loads of modern appliances and devices, leading to potential overheating and failure of the wiring. As a result, many homeowners and inspectors regard it as a concern during home inspections, and it often needs to be replaced or upgraded to meet current safety standards.

In contrast, the other options describe either more modern systems or components that do not apply to knob-and-tube wiring. Thus, understanding the historical context and safety implications of knob-and-tube wiring is essential for anyone involved in home inspections or electrical safety assessments.