Knob and Tube Wiring

During our inspections, we still find many older homes have Knob and Tube Wiring.  This type of wiring is a fire hazard and should be removed and replaced with new wiring by a qualified electrician.

The system is comprised of wiring supported with ceramic knobs with tubes that run through the wood joists and framing and at locations where the wires intersect.

​Knob and Tube wiring is considered unsafe for several of the following reasons:

• The dissipated heat from knob-and-tube wiring can pose a fire hazard if the wires are enveloped in building insulation. A possible exception is fiberglass insulation, which is fire-resistant, although even this type of insulation should not cover knob-and-tube wiring. The homeowner or an electrician should carefully remove any insulation that is found surrounding KT wires.
• Knob-and-tube wiring is more vulnerable to damage than modern wiring because it is insulated with fiber materials and varnish, which can become brittle.
• Some insurance companies refuse to write fire insurance for houses with this type of wiring, although this may be remedied if an electrician can verify that the system is safe.
• Disregarding any inherent inadequacies, existing KT cable systems are likely to be unsafe because they are almost guaranteed to be at least 50 years old.

If you have any concerns about Knob and Tube wiring in your house, contact us to speak with a qualified home inspector.

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