I recently learned about an old electrical wiring method called knob-and-tube that could potentially save me thousands of dollars on rewiring costs in my old house. As a homeowner with an outdated electrical system, I was intrigued to learn more.

What is Knob-and-Tube Wiring?

Knob-and-tube (K&T) is an early standardized method of electrical wiring used from about 1880 to the 1940s. It consists of insulated copper conductors passing through ceramic knobs mounted on wood framing and supported by porcelain tube insulators where wires enter electrical boxes.

This old-fashioned wiring system has some key advantages:

Surprisingly, K&T wiring can still be serviceable and safe when properly maintained.

Why Rewiring is Often Recommended

Many electricians and inspectors automatically condemn K&T wiring and recommend full rewiring with modern NM cable (Romex) instead. Their concerns are understandable:

However, rewiring a whole house with Romex can cost tens of thousands of dollars. Determining if K&T can be serviced safely could save me a lot of money.

Evaluating Your Existing Knob-and-Tube Wiring

Here are some steps I plan to take to evaluate the K&T wiring in my house:


Load testing

Insulation testing

Exposed wiring

Making Knob-and-Tube Wiring Safer

If the K&T wiring checks out, there are some upgrades I can make to improve safety:

Properly maintained K&T can be reasonably safe for continued use. I plan to have a licensed electrician assess my system to see if targeted upgrades could save me the major expense of rewiring the whole house. With the right approach, this forgotten wiring method could really pay off!