Knob and Tube Removal

Knob and Tube (K&T) wiring is an ungrounded wiring method that was installed in homes built between late 1800's to the 1930's.

It consisted of single-insulated copper conductors run within wall or ceiling cavities, passing through joist and stud drill-holes via protective porcelain insulating tubes, and supported along their length on nailed-down porcelain knob insulators. Where conductors entered a wiring device such as a lamp or switch, or were pulled into a wall, they were protected by flexible cloth insulating sleeving called loom. The first insulation was asphalt-saturated cotton cloth, then rubber became common. Wire splices in such installations were twisted together for good mechanical strength, then soldered and wrapped with rubber insulating tape and friction tape (asphalt saturated cloth), or made inside metal junction boxes.

Knob and tube wiring was eventually displaced from interior wiring systems because of the high cost of installation compared with use of power cables, which combined both power conductors of a circuit in one run (and which later included grounding conductors).

K&T wire was meant to be a free air wiring method. This is because K&T is designed to let heat dissipate to the surrounding air. As a result, energy efficiency upgrades that involve insulating previously uninsulated walls or attic spaces usually also require replacement of the wiring in affected homes.


Since up to 25 per cent of heat loss is through windows, plastic window covers can help reduce drafts. They can be purchased at most hardware stores.


Reduce the temperature on your thermostat when you’re not at home and overnight. Many new thermostats can be programmed to change the temperature automatically.


Replace incandescent bulbs with energy-efficient compact fluorescent bulbs, which are four times more efficient and last about eight times as long.

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