How to Safely Replace Knob and Tube Wiring

Overview of Knob and Tube Wiring

Knob and tube wiring was commonly installed in homes built before the 1940s. This type of wiring consists of individual wires that are run through the walls, attics, and crawl spaces. The wires are supported by ceramic knobs and tubes.

While knob and tube wiring was suitable for the electrical needs of older homes, it can be dangerous by today's standards. The insulation on the wires becomes brittle over time, leading to exposed conductors. In addition, knob and tube circuits are often overloaded as homeowners add more electrical devices over the years. This can cause the wires to overheat, increasing fire risk.

For these reasons, it is usually recommended to completely replace knob and tube wiring. In this article, I will discuss the steps involved in safely replacing this outdated wiring.

Dangers of Knob and Tube Wiring

Before detailing the replacement process, it's important to understand why knob and tube wiring can be so hazardous:

• Fire risk - The insulation breaks down over time, leading to wire damage and overheating. This significantly increases electrical fire risk.

• Lack of grounding - Knob and tube wires typically do not include a ground wire. This can lead to shocks and make the system more vulnerable to surges.

• Overloaded circuits - Older 30-amp circuits are often maxed out as more lights and appliances are added to the home. This also leads to overheating.

• Difficult to repair - The wiring is very difficult to access within walls and attics, making repairs extremely challenging.

Replacing knob and tube wiring entirely eliminates these risks and brings the home up to modern electrical safety standards.

Planning the Replacement Project

Replacing knob and tube wiring is a major project that requires planning and preparation:

• Consult an electrician - Only a licensed electrician has the knowledge and experience to safely remove knob and tube wiring. Get quotes from a few local electricians.

• Have your electrical panel evaluated - Upgrading the wiring usually requires expanding the electrical panel. An electrician can examine your panel and determine if it needs to be replaced.

• Develop a plan and budget - Factor in all costs - the electrician's labor, new wiring, new breakers, and possibly a new panel. Then set a budget and get financing if needed.

• Schedule the work - Find out how long the project will take so you can make arrangements if electrical power will be disrupted.

• Remove belongings - Empty attics and crawl spaces where wiring will be accessed to allow the electrician room to work.

Taking the time to properly plan the project will help ensure it goes smoothly and safely. Rushing into a knob and tube replacement may compromise the quality of work.

Hiring a Qualified Electrician

Only experienced electricians should attempt to replace knob and tube wiring. When hiring an electrician:

• Verify their license - Ask to see their state-issued electrical license and ensure it is current.

• Look for knob and tube experience - Not all electricians have worked extensively with knob and tube removal. Find one familiar with the intricacies.

• Get referrals - Check reviews and ask neighbors for electrician referrals. Referrals are smart since knob and tube wiring is fairly specialized.

• Get multiple quotes - Do not accept the first quote you receive. Interview at least three electricians and compare apples-to-apples quotes.

• Ask about their process - They should detail how they will remove the old wiring, run the new wiring, and handle your electrical panel.

Taking your time to hire the right electrician ensures the very delicate and dangerous task of knob and tube replacement is handled correctly.

New Wiring Installation

Once you've hired an electrician, the wiring replacement process can begin:

Removal of Knob and Tube Wiring

• The electrician will access all areas of the house where knob and tube wiring exists. Attics, crawlspaces, and walls will be opened.

• Wiring is disconnected from the electrical panel. Junction boxes are examined to identify all connections.

• Knob and tube wires are cut back to the boxes and removed. Removal is extremely delicate work requiring great care.

Installation of New Wiring

• Updated NM electrical cable wiring is run through the same paths as the old wiring. For safety, no old wiring can remain.

• Junction boxes are reconnected, and new wiring is run to devices like switches, outlets, and light fixtures.

• All accessible wiring is completely replaced. Inaccessible wires are deactivated and capped off.

• For fire safety, insulation is added or improved where wiring is installed.

Electrical Panel Upgrade

• With the heavy amp loads required by modern homes, the electrical panel usually needs upgrading too.

• The electrician must install a new panel rated for 100+ amps. New circuit breakers are added.

• The new wiring is connected to the upgraded panel. Only once this is complete should power be restored to the home.

Finishing the Project

Once the new wiring installation is complete:

• Test all electrical devices, lights, outlets, and switches to ensure proper function. Contact the electrician immediately about any issues.

• For old wiring that could not be accessed, labels should be added alerting homeowners that abandoned wires exist. This prevents unsafe disturbance in the future.

• Insulation and drywall patching can begin. Use low-VOC and fire-rated materials for safety.

• Lastly, have the completed work professionally inspected. Once approved, paperwork showing the knob and tube wiring replacement will be issued. Keep this documentation on file.

Replacing hazardous knob and tube wiring requires time, budgeting, and hiring the right electrician, but it eliminates the risk of electrical fires. For long-lasting peace of mind, contact an electrician about knob and tube replacement as soon as possible.