Knob and tube wiring is an early method of electrical wiring that was commonly used in homes built from the late 1800s to the 1940s. This method involves running insulated copper wire through ceramic tubes and securing it to wooden framing using knobs. While this type of electrical system was considered safe at the time, it does not meet today’s national electrical code standards and can pose a fire hazard if not maintained properly.

The primary difference between knob and tube wiring and modern wiring lies in the safety features and materials used. Modern wiring typically uses insulated conductors that can handle higher amperages and are designed with built-in safety features, such as breakers instead of fuses. Additionally, modern electrical systems often incorporate ground wires and better insulation methods, reducing the risk of electrical fires. In contrast, knob and tube systems lack grounding and can become a fire hazard if overloaded.

Insulating over knob and tube wiring is not recommended. Doing so can trap heat and potentially lead to overheating, creating a significant fire hazard. If you have knob and tube installations, it is advisable to consult with a qualified electrician or electrical contractor before adding insulation to ensure safety and compliance with the national electrical code.