Knob-and-tube wiring was one of the most premier electrical wiring method in buildings across North America from about 1880 to 1950. The method was totally outdated and has the potential to be a safety hazard if not handled correctly. InterNACHI inspectors should ensure that they disclose knob-an2d-tube wirings while doing inspection. The ESA suggests employing a Licensed Electrical Contractor in GTA if you’ve got knob & tube wiring and tell him to check the health for the same. Also, you can ask for a home electrical system assessment on alternate for making sure you are safe.