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 or ceiling 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 wiring methods:

Fire hazard - The insulation on old wiring can become brittle and crack over time, exposing the conductors and increasing fire risk. Knob and tube lacks a ground wire which can prevent faults from triggering breakers.
Insufficient for modern loads - Knob and tube is designed for minimal lighting and appliance loads. It cannot safely handle the higher wattage of modern appliances and devices.
Difficult to modify - New circuits cannot be easily added, and extending existing ones is complicated. Replacement with modern wiring is often preferable.

For these reasons, knob and tube wiring is considered obsolete and many jurisdictions prohibit its continued use.

Dangers of Knob and Tube Wiring

There are several dangers associated with old knob and tube electrical systems:

Shock hazard - No ground wire means risk of shock from faults. GFCI outlets cannot be installed to protect circuits.
Fire hazard - Degraded insulation can allow conductors to arc to combustible materials. Lack of protection from overloads increases fire risk.
Damage to electronics - No ground wire and poor voltage regulation can damage computers, appliances and other electronics. Surges can destroy equipment.
Insurance issues - Most insurance companies will not cover houses with knob and tube wiring. Or they require an expensive rider with higher premiums.

I cannot stress enough how hazardous knob and tube wiring can be. It is an obsolete, outdated system that simply cannot handle the electrical demands of modern homes safely. Replacement should be a top priority for any home with knob and tube wiring.

Why Replace Knob and Tube Wiring?

There are many compelling reasons to replace old knob and tube wiring in your home:

Make your home safer by reducing fire and shock risks with modern wiring.
Allow installation of GFCI outlets to prevent electrocutions.
Enable full circuit breaking with modern breaker panels to protect from overloads.
Allow grounding of electrical system to eliminate shock hazards.
Increase capacity to handle high wattage modern appliances and electronics.
Allow for adding new circuits and outlets throughout home.
Reduce insurance costs by removing a major hazard flagged by underwriters.
Increase resale value - many buyers won't consider a house with knob and tube.
Improve voltage regulation for sensitive electronics and appliances.
Sleep better at night knowing your home's electrical system is safe and reliable!

Replacing those old wires will bring your home up to modern safety standards. It's a smart investment that can literally save lives.

How to Replace Knob and Tube Wiring

Replacing knob and tube wiring completely with modern wiring is a major project best left to a professional electrician. But here is an overview of what's involved:

1. Turn Off Power and Install New Panel

The power must be shut off at the main panel to ensure wires are de-energized for safety. Then a new modern breaker panel is installed to replace the obsolete fuse box.

2. Run New Wires

Starting at the new panel, new copper wires with ground are run through walls and ceilings to each outlet, switch and fixture. All accessible old wiring is removed.

3. Install New Devices

Wall outlets, switches, light fixtures and appliances are reconnected to the new wiring system. GFCI protection can be added where needed.

4. Inspect and Test

The system is thoroughly inspected and tested for correct wiring, polarity, grounding and function. This verifies all old wiring is deactivated.

5. Restore Walls and Surfaces

Walls and ceilings are repaired and restored after new wires are run through them. Painting finishes the job.

Replacing knob and tube wiring is labor intensive, requiring opening up of walls and ceilings. But it is absolutely necessary to bring a home up to electrical safety standards. The peace of mind is well worth the effort and expense.

Questions to Ask Electricians about Knob and Tube Replacement

When getting quotes from electricians to replace knob and tube wiring, some key questions to ask:

Are you fully insured and licensed for this large a job?
Will you pull all permits required by the city/county?
Do you have experience with knob and tube replacement projects?
Will you install a new grounded electrical panel?
How will you fish the new wires through walls and ceilings?
What building repairs are included after running new wires?
Will you dispose of all old wiring off site legally?
Can I see examples of past knob and tube replacement jobs?
Do you offer any warranties on your work?
What is your estimated timeline for completing the project?
What are the itemized costs for labor, materials, permits, etc?

Doing your due diligence will ensure you hire the best qualified electrician to perform a full, safe, and professional knob and tube wiring replacement in your home.

Hiring a Licensed Electrician is Strongly Advised

While a handy do-it-yourselfer may be tempted to tackle a knob and tube rewiring on their own to save money, I strongly advise hiring a licensed electrician.

Replacing an entire home's electrical system is a complex job with many inherent hazards. Mistakes can lead to deadly fires or electrocution. Your life is simply not worth the risk.

Plus, an experienced electrician will complete the intricate work much faster and ensure the finished product meets all legal requirements. Do yourself a favor and leave it to the professionals.

The money will be well spent for the safety, reliability, and peace of mind a modern electrical system will provide. And you won't have to worry about potential insurance issues down the road.

In Conclusion

Old knob and tube wiring is a relic of the past that has no place in the modern world. The fire, shock and insurance risks make replacement an urgent necessity. Hiring a licensed electrician to install updated, grounded wiring and devices will make your home exponentially safer. Taking this vital step protects your family and adds value to your house. The peace of mind alone makes it a wise investment.