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Don't let owners of more modern homes fool you – knob and tube wiring is actually rather common and is a steady element in older houses. It may help you to have an understanding of the main components involved in this tried-and-true wiring method.

So, what is knob and tube wiring? The term relates to the ceramic knobs that support the wire. The tubing that protects the wire that passes through any woodwork – like floor joists – is also ceramic.


Until 1950, this was the wiring standard used in houses. Because most homes in the Webster Groves, MO and Kirkwood, MO as well as other areas that were built around or before 1950, it's possible that knob and tube is present in yours.

Wires run separately in the knob and tube, the black and white wires have a few inches of space between each. In contrast to knob and tube, the black, white, and ground wires are wrapped into a single cable with modern.

Regarding insulation, plastic is used for modern, while rubber is found in knob and tube. Lastly, while the absence of a ground wire could be seen as a disadvantage for knob and tube, the good thing is that the copper wiring it uses boasts a larger diameter, which means the wires stay cooler as electricity runs its course.

Common issues noted with knob and tube wiring include:

  • Poor connections: this is usually the result of DIY connections made after initial installation.
  • General damage: knob and tube wiring is older and has likely endured the abuse of multiple handymen.
  • Brittleness: the rubber insulation can get brittle over time. Wires in high-heat locations, like ceiling light fixtures, can be affected.
  • Extended circuits: older electrical systems had fewer circuits when compared to today's, so it's possible that each knob and tube circuit has been extended, resulting in poor connections.

These problems may seem daunting, but each one can be handled. There's no doubt you take pride in your home, and you can retain its timeless condition by contacting On Time Electrical, who is vastly experienced and familiar with the ins and outs of knob and tube wiring.

Call our “panel of experts” for help with your electrical panel.