“Why Knob and Tube Wiring is Making a Comeback”

What is Knob and Tube Wiring?

Knob and tube wiring was an early standardized method of electrical wiring used in buildings in North America from about 1880 to the 1940s. It consisted of single insulated copper conductors run within wall cavities, passing through joists and studs.

The wiring was supported along its length by knob insulators. Where wires entered a wiring device such as a lamp or switch, or were pulled into a wall, they were protected by flexible tubing insulators. This system was an improvement over previous wiring methods as it included some safety features such as separation of conductors and placement away from combustible materials.

Key Features of Knob and Tube Wiring

Why Did Knob and Tube Wiring Fall Out of Favor?

Knob and tube wiring began to decline in popularity in the 1930s and was essentially obsolete by the 1950s. Several factors led to the shift away from knob and tube:

Limitations of Knob and Tube

Safer New Alternatives

Obsolescence of Old Construction Methods

Why is Knob and Tube Making a Comeback?

While knob and tube wiring is obsolete for new construction, interest in maintaining or replicating it in historic restorations has risen. Some of the reasons it's gaining renewed popularity include:

Historic Preservation

sustainability and Reduced Waste

Lower Cost

Is Restored Knob and Tube Wiring Safe?

While knob and tube has its limitations, it can be restored and adapted to modern safety standards:

Properly maintained knob and tube can provide continued safe and reliable electrical service while preserving historic charm. Reuse and repair allow reducing demolition waste while maintaining or matching historic aesthetics. With proper precautions and upgrades, adapted knob and tube wiring can meet modern electrical safety codes.