Knob and tube was the wiring system for homes built before 1950 which the majority of those house are still exist.
Occasionally, knob and tube wiring is found to be fire hazardous and dangerous for three reasons:
- Knob and tube is consist of a rubber insulated jacket around electrical conductor. On the top of this jacket is also a flammable cloth wrapped around the electrical conductor. This wiring system supported by porcelain knob and tubes throughout the house. By the time from 1950 till now probably some of this insulation jacket and cloth are deteriorated.
- If the original wiring system of knob and tube changed due to some renovation in the house by a handyman, some times found out the circuit tapped and spliced, to the knob and tube wiring system instead of running the wire back to the main panel. Such a problem is a complete no for electrical safety perspective.
- The knob and tube were designed to power up the 2-prong outlets, which means the ground protection wiring system is not exist in the receptacles. That makes even harder because not only the house is in fire hazard but also the people living in such a house are in high risk of electrical shock.
Switch Tech Electric recommendation is to replace the knob and tube wiring system in the entire house and make it more up to date to the Canadian Electrical Code Book.