How a Forgotten Knob-and-Tube Wiring System Could Burn Down Your Home

As a homeowner, I never imagined that the hidden wiring inside my walls could be a fire hazard. That changed when I learned about an antiquated electrical system called knob-and-tube wiring. This forgotten wiring method was common in homes built before 1950 and can pose serious fire risks if left in place. In this article, I'll explain what knob-and-tube wiring is, why it's dangerous, how to detect it, and what you need to do if your home still contains this outdated wiring.

What is Knob-and-Tube Wiring?

Knob-and-tube (K&T) wiring was commonly installed in American homes built between 1880 and the 1940s. It consists of single black rubber-insulated wires passing through ceramic knobs mounted on framing and tubes used to protect wires through open spaces.

Unlike modern electrical wiring systems which use a grounded metal conduit to protect wires, K&T wiring is completely ungrounded and provides no protection from incidental contact. The wires are often covered in cloth or tar paper insulation that can easily crack or deteriorate over time.

Why Knob-and-Tube Wiring is a Fire Hazard

There are several factors that make aging K&T wiring a serious fire risk:

Any of these factors can lead to electrical fires that can spread rapidly through homes. K&T wiring caused an estimated 25,000 fires per year in the late 1980s according to the Consumer Product Safety Commission. Fires often start in walls and can go undetected for a long time.

How to Check if Your Home has Knob-and-Tube Wiring

If your home was built before 1950, there's a good chance it contains at least some K&T wiring. Here are some ways to check:

If you confirm or even suspect there is old K&T wiring present, it's essential to take action to prevent a fire tragedy.

What To Do if Your Home Has Knob-and-Tube Wiring

Here are your options if you discover K&T wiring in your vintage home:

The only sure way to remove the fire risk is a complete rewiring. While expensive, this will drastically improve the safety and value of your vintage home. If full rewiring isn't feasible right away, prioritize the most hazardous areas first. But never ignore old knob-and-tube wiring - it could lead to the destruction of your beloved historic home.