What is knob-and-tube wiring primarily used for in homes?

Knob-and-tube wiring is primarily used for supporting and insulating conductors from timber components. This wiring system consists of insulated copper conductors that are run through ceramic knobs and tubes, which are designed to secure the wires in place and protect them from contact with wooden structural components of the building. The use of knobs helps maintain a safe distance between the conductors and the timber, reducing the risk of fire hazards that could arise from potential contact. The tubes serve to protect the wires as they pass through walls or other wooden structures, ensuring that they remain insulated and secure.

The design of knob-and-tube wiring reflects historical practices of electrical installation, where it was essential to keep wires away from combustible materials while also providing adequate support for the wiring system.