How to Replace Old Knob and Tube Wiring

How to Replace Old Knob and Tube Wiring


Replacing old knob and tube wiring in your home is an important upgrade that can improve safety and allow your electrical system to handle modern appliances and electronics. This type of wiring was commonly installed in homes built before the 1940s. While it may have served homes well for decades, knob and tube wiring can present fire and shock hazards if left in place too long.

In this guide, I will walk you step-by-step through the process of replacing knob and tube wiring. We will cover planning the project, gathering supplies, removing old wiring, installing new wiring, connecting circuits, and finishing the job. With proper planning and care, you can upgrade the wiring in your vintage home and gain peace of mind knowing it is safer.

Dangers of Knob and Tube Wiring

Before we get into the how-to, let's review why knob and tube replacement is so important:

Replacing knob and tube wiring entirely removes these risks from your home. Doing this project yourself can save thousands of dollars compared to hiring an electrician. With proper precautions, you can take on this project DIY.

Working Safely

When dealing with electrical wiring, safety should always be your top priority:

Proceeding cautiously will help ensure you and your home stay safe throughout this major wiring project.

Gathering Supplies

Before getting started, you will want to ensure you have all necessary materials on hand:

Having all supplies ready will prevent delays once you start the rewiring work.

Removing Old Knob and Tube Wiring

With safety gear on and supplies at hand, we can get started:

1. Turn Off Power

Shut off the main breaker and verify power is off with a voltage tester. This may require flipping additional breakers as well.

2. Remove Wiring from Walls and Ceilings

Start by taking down any accessible wiring, removing it from conduits and pulling it out of walls by fishing down from above. Take care not to damage wall and ceiling surfaces.

3. Disconnect Devices

At light fixtures, switches and outlets, disconnect the old wiring. Label wires to note locations and what they power.

4. Remove Knobs, Tubes and Junctions

With wiring disconnected, unscrew any remaining knob and tube hardware. Also remove old junction boxes no longer needed.

5. Pull Wires Out Completely

Finally, pull any remaining wires out from walls and ceilings. Seal up holes as needed for safety.

Work carefully and methodically to get all the old wiring out. This will leave you with a clean slate for the new wiring.

Installing New Wiring

Once the old knob and tube wiring is fully removed, we can install safe, modern wiring:

1. Plan Circuits

Determine where to run each new circuit in the house. Group lighting and outlets appropriately based on rooms and usage.

2. Run Cables

Run new cables through walls and ceilings to each outlet and switch location. Leave extra length for connections. Use conduit where required.

3. Install Junction Boxes

Mount new junction boxes where wiring will be joined. Feed cables into boxes and clamp properly.

4. Make Connections

Join wire ends using twist-on connectors. Follow wiring diagrams created in earlier steps.

5. Secure Wires

Keep wires tidy and secure inside boxes. Allow slack for adjustments. Reinstall switches, outlets, lights.

6. Install Breakers

For any new circuits, install appropriately sized circuit breakers in the main panel.

Follow codes carefully throughout the installation process. Consult local building department with any code questions.

Connecting the New Circuits

With the new cables run throughout the home, we can now join them together into complete circuits:

Take the time to make neat, secure connections. This will ensure your new circuits work properly and safely.

Finishing Touches

Once all new wiring is in place and connected, there are a few final steps to wrap up the project:

With diligent attention to detail throughout the process, you can feel confident your home's wiring is now far safer and ready to meet your family's needs.


Do I need to upgrade my electrical service when I rewire?

Can I leave some old wiring in place?

Is rewiring something a DIYer can take on?

Does homeowners insurance cover electrical fires related to old wiring?

How much does a full rewire cost?


While rewiring an entire home is a major undertaking, it is a project an ambitious DIYer can certainly take on. With careful planning, safety precautions, and attention to detail, you can eliminate the dangers of knob and tube wiring. Your home will benefit from safer, modern wiring supporting today's electrical needs.