Hello,

While conducting minor renovations to a vacant group home, knob and tube wiring was discovered in the ceiling. It is definitely a possibility that other circuits in the group home would also be knob and tube type.

As per CEC, would it be required to remove only the discovered part of the knob and tube and replace with standard wiring method or would the code mandate replacement of all of the knob and tube type wiring.

On a safety perspective, all of the knob and tube wiring (discovered and undiscovered) should be replaced. I suppose the AHJ would also have a similar requirement. But is there an acceptable and safe scenario, where only the discovered part of knob and tube wiring and circuit is replaced and the remaining part of knob and tube wiring is inspected for insulation deterioration and left in place to be replaced during a major renovation project. Is wiring permit usually approved on partial replacement of knob and tube wiring? Also is there a possibility of safety hazard when the two different type of wiring are present at the same time i.e. knob and tube and standard conduit?

Thank you.