How to Replace Old Knob and Tube Wiring

How to Replace Old Knob and Tube Wiring

What is Knob and Tube Wiring?

Knob and tube wiring was an early standardized method of electrical wiring used in buildings in the United States from about 1880 to the 1940s. It consists of single insulated copper conductors run within wall cavities, passing through joist and stud drill-holes via protective porcelain insulating tubes, and supported on nailed-down porcelain knob insulators.

This old type of wiring has some major drawbacks compared to modern electrical systems:

For these reasons, knob and tube wiring is considered obsolete and dangerous by modern standards. Most electrical codes require it to be replaced in any homes where it still exists.

Why Replace Knob and Tube Wiring?

There are several important reasons to replace knob and tube wiring in your home:

How to Find Knob and Tube Wiring in Your Home

If your home is over 50 years old, it may contain some original knob and tube wiring. Here are some ways to check if it's present:

When to Call a Professional

I highly recommend having a licensed electrician inspect your home for knob and tube if there's any chance it exists. They can safely confirm if and where it's present.

Once found, always hire an electrician to perform the replacement work. The risks of DIY are too high with outdated electrical wiring. The project also often involves significant changes to wires within walls and the main electrical panel. Professionals have the expertise to handle this delicate process.

How Knob and Tube Wiring is Replaced

Replacing knob and tube wiring completely revamps the electrical system with modern wires, outlets, switches, and safety features. The general process involves:

1. Full Inspection and Planning

2. Install New Electrical Panel

3. Run New Wiring and Outlets

4. Connect Devices and Fixtures

5. Remove Old Components

Cost to Replace Knob and Tube Wiring

The cost to replace knob and tube wiring in a home generally ranges from $8,000 to $15,000. However, prices can vary dramatically based on:

To determine the investment for your specific project, get quotes from licensed electricians. Be sure to get at least 3 bids for the best deal.

Is Knob and Tube Wiring Dangerous?

The short answer is yes, knob and tube wiring is considered dangerous by today's electrical standards for several reasons:

While historic, knob and tube does not provide the safety, capacity, or reliability of modern electrical systems. Homeowners should have it inspected and replaced as soon as possible.

Electrical Code on Knob and Tube Wiring

Most modern electrical codes consider knob and tube wiring unacceptable and require upgrades. For example:

Always check your local electrical code for the exact rules in your area. But in general, regulators and officials consider knob and tube wiring obsolete and hazardous due to its limitations.

Is It OK to Leave Some Knob and Tube Wiring?

Electricians do not recommend leaving any original knob and tube wiring in place. Some reasons it should always be fully replaced:

While full K&T replacement is expensive, experts strongly advise against any shortcuts. Removing all the outdated wiring is by far the safest option.

In Conclusion

Knob and tube wiring is too dangerous and insufficient for modern electrical loads. Homeowners should have their system evaluated by a professional electrician. In most cases, completely replacing K&T with updated wiring, outlets, and an electrical panel is required for safety. Though not a cheap project, the investment protects your home and provides peace of mind.