For homes built before the 1950s in the Delaware Valley & Greater Philadelphia Area, knob and tube replacement can be an important electrical safety improvement. State of the art at the time, this system of stringing rubber-insulated wiring along a series of ceramic knobs and tubes is long outdated. Aging materials and updated wiring standards make tube replacement with plastic-jacketed wiring a wise choice.
In addition, updating the two wires used earlier to today’s three-wire system, including a ground wire, helps avoid shocks and electrical fires. While this system can look elegant running through your attic and walls, having your power run through it presents risks and limitations.