What is knob and tube wiring? And why should it be replaced?
Knob and tube wiring is a type of wiring that uses single wires supported by ceramic insulators. The good is it is difficult to overheat this type of wiring. The bad is it is usually cloth wrapped and has no ground. This type of wiring was in general used before WWII but it's recommended that if you find it being used that you replace it. Not only that, but some insurance companies won't cover properties that have Knob and Tube wiring, and if they do, it will cost significantly more. No new properties are developed with knob and tube wiring.