How to Safely Rewire Your Home Using Obsolete Knob and Tube Wiring

Understanding Knob and Tube Wiring

Knob and tube wiring was commonly installed in homes built before 1950. This type of wiring consists of individual wires that are run through the wall cavities. The wires are supported by ceramic knobs and tubes between joists and studs.

While knob and tube wiring was suitable for the electrical loads when it was installed, it can be dangerous by today's standards for the following reasons:

The wiring lacks a ground wire, which is essential for safety with modern appliances. This can increase the risk of shocks.
The insulation breaks down over time, exposing live wires that can spark and cause fires.
It can only handle lower amperages than modern wiring. Circuits can be easily overloaded with today's electrical usage.
The wires run through open air rather than through a protective conduit. This leaves the wiring exposed to damage.

Should I Rewire?

Given the safety hazards, I recommend completely replacing knob and tube wiring whenever possible. Here are reasons why rewiring is the best option:

It is the only way to provide modern grounding and GFCI protection. This greatly reduces shock and fire risks.
Higher capacity wiring can be installed that meets modern electrical demands. This reduces tripped breakers and overheating.
New insulated wires are protected from incidental damage that leads to shorts and fires.
Proper rewiring allows circuit labeling so all wires are identifiable. This improves safety for future electrical work.
Rewiring increases your home's value substantially. Homebuyers consider knob and tube wiring a major detractor and safety hazard.

While I don't recommend it, you can opt to just replace the knob and tube with modern wiring in the specific locations where you need more capacity. However, the above benefits make full rewiring the best long-term choice.

Dangers of Partial Rewiring

It may be tempting to only rewire the sections of knob and tube circuits that you are using. However, this approach has serious risks:

Overloading - Partial rewiring can funnel more power through old wiring than it was designed for. This leads to extreme fire and shock hazards.
Incorrect wiring - Attempting electrical work without proper training often results in improper and dangerous connections.
Lack of grounding - You cannot ground any wiring without rewiring the entire circuit. Ungrounded wires remain very dangerous.
Insurance issues - Most insurers will not cover homes with partially rewired knob and tube. It is considered an unacceptable risk.

I strongly advise against partial knob and tube rewiring given the unpredictability of old wiring and the inherent safety issues involved. The proper solution is to fully rewire your home.

Safety Precautions When Rewiring

Rewiring knob and tube circuits is a dangerous endeavor for the amateur. Make sure to take these precautions:

Turn off power at the main breaker - With both knob and tube and modern wiring present, treat all wires as live. Verify power is off with a tester before handling any wires.
Inspect the attic carefully - Look for any exposed wiring or damaged insulation. These present serious shock and fire hazards.
Keep all wiring clearly labeled - Improper connections to old wiring can overload circuits. Meticulously label wires to avoid confusion.
Hire an electrician - Unless you are fully trained and have experience with rewiring old homes, hire a professional electrician to handle it safely.
Inform your insurance company - Notify your insurer of your plans to rewire. Only do the work with their approval to avoid insurance issues.
Install GFCI outlets - Once rewired, install GFCI outlets for protection in wet areas like kitchens and bathrooms.

Proceeding carefully and with professional help is crucial when rewiring obsolete knob and tube wiring. Never take risks with electrical safety in your home. Follow all precautions.

Finding the Right Electrician

Attempting to rewire knob and tube circuits without proper training is extremely dangerous and is not worth the risk. Be sure to hire a professional electrician to complete the rewiring safely.

When hiring an electrician, look for the following:

Licensed and insured - Verify they are properly licensed in your state and carry liability insurance. This protects you if anything goes wrong.
Experience with old wiring - Choose an electrician who is very familiar with safely rewiring vintage electrical systems like knob and tube.
Good references - Ask for multiple references from recent jobs and contact them. Check reviews online as well.
Detailed quote - Get a quote that clearly outlines the scope of work and what is included. Make sure it aligns with your goals.
Availability - Find out their schedule and expected timeframe for completing the rewiring project. A long wait can be inconvenient.

Avoid any electricians who cut corners or make the project sound simpler than it is. Rewiring knob and tube is difficult work that requires expertise. With the right electrician, you can finally make your electrical system safe.

Cost and Timeline

Here is a realistic overview of the cost and timeline to expect for a full knob and tube rewiring project:

Total cost - The average cost to completely rewire a 2500 square foot home is $8,000 to $15,000. Quotes from contractors can vary widely.
Supply cost - The wiring supplies alone will be $2,000 to $4,000 depending on the home's size and layout.
Labor cost - With an electrician's work included, total labor will cost $5,000 to $10,000 or more.
Timeline - The project will take most electricians 1 to 2 weeks from start to finish. More complex homes may require longer.
Inspection - Once finished, the local building department will need to inspect the work and issue a certificate of approval. This can take 3-7 days.

While not cheap, a full rewiring is a smart investment that drastically improves your home's safety and value. Get multiple quotes to find the best rate for your specific situation.

Alternatives to Rewiring

While a full rewire is my recommended solution, here are a couple alternatives to consider:

Electrical overlay - This involves installing a new grounded wiring system over the existing knob and tube. It is cheaper but still provides grounded outlets. However, the old wiring remains in place which is not ideal.
Circuit breaker upgrade - Upgrading your main circuit breaker panel from fuse to breaker improves safety. But it doesn't address the capacity, grounding, and insulation issues with knob and tube wiring.
Individual subsystem upgrades - You can upgrade specific subsystems like lighting or appliances separately. However, the overall risks associated with deteriorated insulation and lack of grounding remain.

Overall, these alternatives improve safety to some degree but leave much of the obsolete wiring in place. I believe complete rewiring is the best and safest choice for most homes and budgets.

In Summary

Rewiring knob and tube wiring is the only way to bring a vintage home fully up to modern safety standards. While expensive, addressing fire and shock risks makes it a wise investment. Take all precautions, do thorough research, and hire a professional electrician to complete the work safely. The result will be a home electrical system that meets today's needs and provides protection for many years to come.