How to Safely Replace Knob and Tube Wiring

How to Safely Replace 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 Canada and the United States from about 1880 to the 1940s. It consisted 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 system has many safety hazards compared to modern electrical wiring methods. The insulation on the wiring can deteriorate over time, exposing live wires. The wires are often spliced together in unsafe ways. The system lacks a proper ground wire, increasing the risk of shocks. Fires can start where wires come into contact with combustible materials inside walls.

Dangers of Knob and Tube Wiring

As a homeowner with knob and tube wiring, I am very concerned about the safety risks, including:

Dangers of DIY Repairs

I certainly do not recommend trying to repair or replace knob and tube wiring yourself, as that could be extremely hazardous. Here are some of the key dangers:

Safely Upgrading Knob and Tube Wiring

The only true solution is to have the knob and tube wiring replaced entirely by a licensed electrician. This is the safest approach I highly recommend. The key steps would include:

Finding a Reputable Electrician

Inspection and Planning

Removal and New Wiring

Restoration and Repairs

Safety Checks and Approval

Costs of Replacing Knob and Tube Wiring

Rewiring an entire home with knob and tube wiring can cost $8,000 to $15,000 on average. Factors affecting the costs include:

Partial rewiring of some rooms or circuits can cost $2,000 to $5,000. I recommend setting aside 15% extra for any unforeseen issues during the electrical work. Get quotes from multiple electricians to find a fair price.

While expensive, rewiring will improve electrical safety and allow you to power modern devices. It can also increase your home's value significantly. Your home insurance rates may also go down.

Home Insurance Issues

Most insurance companies will not insure homes with knob and tube wiring due to the substantial fire risks. Exceptions are sometimes made if:

However, policies with exceptions like this often have higher premiums or limitations on liability coverage. Sometimes the insurance company will require repairs within a set timeframe in order to maintain coverage.

So in most cases, it is wise to proactively upgrade the wiring in order to obtain normal rates and coverage. Discuss this issue with your insurance agent.

Electrical Permit Requirements

In most jurisdictions, you will need a permit for replacing knob and tube wiring, which requires passing inspections. The steps usually include:

The electrician will then need to:

Permits help ensure the work meets the National Electrical Code. Failing to get a permit can risk fines, insurance problems, and issues when selling the home.

In Conclusion

Given the substantial fire and shock dangers of old knob and tube wiring, I highly recommend hiring a professional electrician to replace it completely.

While expensive, rewiring will provide much improved electrical safety and reliability. Make sure to get your insurance company and local permit office involved early in the process. With the proper planning and licensed electrician, you can successfully upgrade this outdated and hazardous wiring in your home.