This was the standard method of wiring homes in North America between 1875 and 1930.
It consists of copper wires run through ceramic knobs and tubes and uses air to dissipate heat. This is why early homes were built without insulation in the walls or attic.
While not inherently unsafe, having knob-n-tube wiring in your home does present some safety issues, most of which come from the system becoming brittle with age, improper splicing into modern wires, and covering with insulation in attics and walls.
You also can’t safely use 3-prong outlets with knob-n-tube wiring. Here’s a graphic to show you what it looks like:
Today, many homeowner insurance companies have issues with these homes, so I always tell my clients to contact their insurance company to ensure coverage is available and reasonable.
Learn more about your home’s electrical service in our blog post.
