How to Keep Your 1920s Knob and Tube Wiring Safe and Up to Code

Knob and tube wiring was commonly installed in homes built in the 1920s. While this type of wiring was safe when it was first installed, it can become hazardous over time. As a homeowner with knob and tube wiring, it's important to understand the risks and follow key safety practices to keep your vintage electrical system up to code.

What Is Knob and Tube Wiring?

Knob and tube wiring consists of single black rubber-insulated wires passing through ceramic knobs mounted to framing members and ceramic tubes inserted through framing cavities. This early form of electrical wiring was common in homes built in the 1920s and earlier.

While knob and tube wiring has largely been replaced by newer and safer electrical systems, it can still be found in some older homes. As knob and tube ages, the insulation breaks down and the wires become brittle, increasing fire and shock risks.

Dangers of Outdated Knob and Tube Wiring

There are several dangers associated with keeping original 1920s knob and tube wiring in your home:

Keeping 1920s Wiring Safe

While it's ideal to completely replace knob and tube wiring, some basic safety practices can reduce risks if upgrades aren't possible right away:

Inspect Annually

Limit Electrical Loads

Update Electrical Panels


Don't Conceal Wiring

Hire an Electrician

Replacing Knob and Tube Wiring

For optimal safety, it's highly recommended to fully replace vintage knob and tube wiring. Here's what to know:

While replacing knob and tube wiring can be a significant investment, it eliminates the serious safety risks of outdated electrical systems. Once upgraded, you can enjoy safe, modern wiring that meets all codes.