Updating knob tube wiring
Fairly common in houses built before 1930, the system uses porcelain insulators (knobs) for running wires through unobstructed spaces.
Porcelain tubes protect wires that run through studs and joists.
His basic theory was that if you keep the wires cool, and they haven't caused you trouble yet, it's unlikely to cause a problem.
Granted that advice was about 15 years ago and none of that wiring is improving with age. It's very likely that you will introduce a problem between the coating and the wire.
As stated above, Knob and Tube and insulation (loose fill or fiberglass batts) don't mix, because it is essential that the wires are free to dissipate heat. In fact, the United States National Electric Code (NEC) section 324-4, forbids the use of loose, blown-in, or expanding foam insulation over Knob and Tube wiring. Unfortunately, I don't have more photos from down here.
Sure I could work around the old wiring and only insulate where there wasn't any, but I've been meaning to replace the Knob and Tube for a while now. The rest of this article addresses what to expect when replacing Knob and Tube wiring. I had places where the rubber insulation had fallen off, exposing a few inches of bare wire in many places.
In the end I went with the guy I felt most comfortable with.
You don't want it in your house for a number of reasons.
Dear Home Inspector: Our home inspector recommended replacing the knob and tube wiring in our home.
But my father-in-law says there's nothing wrong with leaving it alone. CTA When installed correctly knob and tube wiring was, in some ways, superior to current wiring practices.
This is all important information to have before undertaking a big electrical project, and if you're thinking about buying a home, you may want to factor it into the contract negotiations.
Overall, the benefits vastly outweigh knob and tube replacement cost, making it a smart decision for homeowners.