What is Knob and Tube Wiring?

Knob and tube wiring, also known as K&T wiring, is an early electrical wiring system that was commonly installed in homes and buildings in the United States and Canada from the 1880s into the 1940s. It gets its name from the knob insulators and tube conduits used to run and protect the wires.

Unlike modern wiring systems that use plastic or rubber insulation around a single conductor, K&T wiring consists of two or more bare copper wires run through porcelain knob insulators and thin conduit tubes. The wires are separated from each other and suspended away from combustible surfaces, hence the 'knob and tube' name.

K&T wiring has largely fallen out of use and is now considered obsolete and potentially dangerous by modern standards.

Why Knob and Tube Wiring is a Fire Hazard

While K&T wiring was considered safe and reliable when first introduced, it poses several fire risks compared to modern electrical systems:

In fact, houses with knob and tube wiring have a significantly higher risk of electrical fires compared to modern wired homes. The older, deteriorated insulation is simply ill-equipped to handle our modern electrical usage.

Dangers and Signs of Faulty Knob and Tube Wiring

As K&T wiring continues to age, signs of failure can become apparent:

Any signs of damaged or overheating K&T wires should be addressed immediately to prevent fire from igniting within walls.

K&T Wiring Hazards when Remodeling or Upgrading Home

Remodeling or upgrading a home with knob and tube wiring poses additional fire risks:

Extreme caution must be taken when modifying or upgrading homes with live K&T wiring to avoid creating new fire hazards. Ideally, the old system should be completely removed by an electrician.

Is Your Home Still at Risk with Knob and Tube Wiring?

If your home dates from the 1930s or earlier, it likely contains knob and tube wiring which poses a serious fire hazard as it continues to age and deteriorate beyond its expected lifetime. Warning signs like tripped breakers, flickering lights, and buzzing outlets indicate your K&T system may be failing.

Home insurance companies often refuse to cover houses still containing live knob and tube wiring due to the substantial risks. They may cancel your policy outright or require replacement of the old wiring before continuing coverage.

Like asbestos and lead paint, knob and tube wiring is now considered a dangerous obsolete technology that has no place in modern homes. Replacing hidden K&T wiring can be expensive, but your life and home are worth the investment. Consult with a qualified electrician to perform an inspection and discuss your wiring replacement options.