How to Replace Dated Knob and Tube Wiring


I want to talk about the process of replacing knob and tube wiring in your home. Knob and tube wiring was commonly installed in homes built before the 1940s. It features exposed wires running through ceramic knobs and tubes. While it was suitable at the time, knob and tube wiring is now outdated and potentially dangerous. Replacing it can significantly reduce fire risks and allow you to use modern appliances. In this article, I'll go through everything you need to know to successfully replace knob and tube wiring.

Dangers of Knob and Tube Wiring

Before we get into the replacement process, it's important to understand why knob and tube wiring needs to be replaced in the first place. Here are some key reasons:

Replacing knob and tube wiring provides huge safety and financial benefits, so let's look at the process.

Planning the Replacement Project

Replacing your home's electrical wiring is a big project that requires careful planning:

Hiring an Electrician

I strongly recommend hiring a licensed and experienced electrician to replace knob and tube wiring. The project involves dealing with live electrical lines, which can be extremely hazardous. Leave it to the professionals. Make sure to get multiple quotes and check reviews before choosing an electrician.

Getting Necessary Permits

Check with your local building department to see what permits are required. The electrician will usually obtain the proper permits, but it's good to be aware of them. Common permits include electrical, plumbing, and structural.

Determining Scope of Work

The electrician will examine your home's wiring and determine the full scope of work required. Key factors include:

Knowing the full scope of work allows proper budgeting. Be prepared for a potentially big project.


Costs for replacing knob and tube wiring vary greatly based on your home's specifics, but $8,000 to $15,000 is typical. Get multiple quotes to compare pricing. Also factor in costs for repairing walls, plumbing, etc after the old wiring is removed. Budget adequately and consider financing options if needed.

Timing the Project

Plan the project during cooler weather when you can safely go without air conditioning for a few days. Also avoid major holidays. Give yourself extra time in case of delays or unexpected issues.

Replacing the Wiring

Once the project is planned out, it's time to replace the outdated wiring:

Removing Knob and Tube Wiring

The electrician will:

Removing all the old wiring can take several days for a whole home.

Running New Wiring

Modern electrical wire comes in plastic or rubber sheathed cables. The electrician will:

Proper circuit labeling at the panel makes the system organized and safe.

Installing Grounding

A key upgrade is installing grounding wires. The electrician will:

Proper grounding means the whole system is now up to modern safety standards.

Inspecting and Testing

Once the new wiring is installed, the electrician will:

Thorough inspection and testing ensures long-term safety and reliability.

Finishing Up the Job

The last steps include:

Wall Repair

Holes drilled for wiring will need patched up with plaster and paint. The electrician can handle this or you can hire a general contractor. Proper patching keeps your home looking good as new.

Panel Upgrade

If needed, upgrade your home's main electrical panel to support added circuits. A 200 amp panel is typical for modern homes.

Final Inspection

The local building department will perform a final inspection before giving approval. This ensures all work was completed to code.


Finally, clean up any dust or debris from the wiring replacement. Check that furniture is put back properly. Install plates and covers over outlets. Your home should now be safe with modern wiring!

Replacing knob and tube wiring is a major undertaking, but worthwhile for safety and peace of mind. Follow this process and work closely with electricians and inspectors to get the job done right. You'll gain significant safety benefits and improve your beautiful home.