When inspecting, what is an important factor to check regarding knob-and-tube wiring?

When inspecting knob-and-tube wiring, an essential factor to consider is that it should not be surrounded by insulation. This is crucial because knob-and-tube wiring was designed with specific characteristics that function optimally when the wires are air-cooled. When insulation encases this type of wiring, it can trap heat and potentially lead to overheating, creating a significant fire hazard. Therefore, proper ventilation around knob-and-tube wiring is necessary to prevent excessive heat buildup.

The visibility of this wiring in attic spaces is also important for ensuring that it can be monitored and inspected, but the primary concern during an inspection relates to the surrounding environment and safety.