How to Troubleshoot Old Knob and Tube Wiring

How to Troubleshoot Old Knob and Tube Wiring


As a homeowner with an older house, I often have to deal with old knob and tube wiring. This type of electrical wiring was commonly used in homes built before 1950. While it can still be functional, knob and tube wiring often needs repairs and upgrades. In this article, I will provide a step-by-step guide on how to troubleshoot and safely repair old knob and tube wiring.

Understanding Knob and Tube Wiring

Knob and tube wiring consists of individual wires that are run through open air, on porcelain knobs, and through porcelain tubes. It does not have a ground wire and the wiring is often brittle or cracked from age. Some key facts about knob and tube wiring:

Signs You May Have Problems with Knob and Tube Wiring

Some common signs of problems with knob and tube wiring include:

If you notice any of these warning signs, it's important to thoroughly inspect and troubleshoot your old electrical wiring.

Safety Tips for Inspecting Old Wiring

When dealing with knob and tube wiring, safety should always be your top priority. Follow these tips to safely inspect old wiring:

Inspecting Visible Wiring and Components

Once you have safely powered off the circuits, start inspecting any visible knob and tube wiring:

Also inspect light fixtures, switches, outlets, and junction boxes for problems. Signs of issues include overheating, odors, discoloration, noise, and sparks.

Checking Wiring Condition in Walls

While much of the knob and tube wiring may be hidden in walls, there are ways to inspect it:

Finding deterioration or violations in hidden wiring can indicate a need for full replacement.

Testing Circuits and Troubleshooting Problems

To thoroughly troubleshoot old wiring, testing of individual circuits is needed:

Considering a Knob and Tube Wiring Replacement

If old knob and tube wiring is deteriorated or improperly modified, full replacement is often necessary:

Replacement does come at a significant cost - often $8,000 to $15,000 on average. Get quotes from licensed electricians to determine the investment.

Working Safely with Electrical Professionals

With safety as the priority, partnering with qualified electricians is highly recommended:

Proper repairs or replacement of old knob and tube wiring improves safety and reliability. By following safe practices and working with professionals, you can tackle this electrical upgrade project confidently. Let me know if you have any other questions!