How to Rewire Your Home Using Knob and Tube Wiring

What is Knob and Tube Wiring?

Knob and tube wiring was commonly installed in homes built before 1950. This old electrical wiring system consists of individual wires that are run through the walls, attic, and crawl spaces.

The wires are supported and spaced apart by ceramic knobs, and where wires cross, they pass through a ceramic tube. This exposes the wires to the open air instead of being protected by insulation like modern electrical wiring.

While knob and tube wiring was suitable for the electrical needs of old homes, it can be inadequate, unsafe, and a fire hazard in modern homes with higher electrical loads.

Dangers and Downsides of Knob and Tube Wiring

There are several dangers and downsides associated with knob and tube wiring:

• Fire hazard - The insulation on old knob and tube wiring can deteriorate over time, exposing the copper wiring which can create shorts, sparks, and electrical fires.

• Insufficient for modern loads - Knob and tube wiring was designed for simple electrical systems with 40-60 amps. Modern homes with AC units, multiple appliances and electronics can overload the system.

• Exposed wires - Knob and tube wires that run through attics, walls, and crawl spaces are exposed and unprotected. This also poses a risk for electrocution.

• Difficult to repair - It can be challenging to access and repair knob and tube wires that are inside walls and ceilings. Finding a qualified electrician familiar with knob and tube can also be difficult.

• Incompatible with electrical safety devices - GFCIs, AFCIs, and surge protectors may not function properly or be compatible with ungrounded knob and tube wiring.

• May not meet insurance requirements - Many insurance providers refuse to insure homes with knob and tube wiring due to the substantial fire risks.

Why Rewiring with Modern Wiring is Recommended

Given the substantial risks posed by old knob and tube wiring, it is highly recommended to completely rewire your home to modern electrical standards for safety.

Here are some key reasons why rewiring is necessary:

• Eliminate fire hazards from deteriorated insulation and wiring.

• Upgrade the electrical system to handle the needs of modern appliances and electronics.

• Provide sufficient power and circuits for all your electrical needs.

• Enjoy reliable, high-quality power without flickers when using multiple devices.

• Take advantage of safety features like grounding and overcurrent protection with circuit breakers.

• Meet insurance companies' electrical requirements.

• Increase your home’s value significantly by having a modern, safe electrical system.

Electrical Code Requirements

It is essential that any rewiring work complies with the latest version of the National Electrical Code (NEC) and local building codes and regulations.

Some key requirements per the NEC include:

• Circuit breakers - Must have dedicated circuit breakers controlling all circuits, instead of outdated fused panels.

• GFCI protection - Receptacles in wet areas like bathrooms and kitchens must be GFCI protected for safety.

• AFCI protection - Arc fault circuit interrupters are now required for bedroom circuits to prevent electrical fires.

• Grounding - All new wiring must include equipment grounding conductors.

• Box fill - Only a specified amount of wires are permitted in each electrical box.

• Wire size - Minimum wire sizes are specified based on circuit amperage and length.

Hiring an Electrical Contractor

Due to the complexity, safety risks, and code requirements involved, I strongly recommend hiring a licensed and insured electrical contractor to handle any knob and tube rewiring work.

Be sure to get multiple quotes, verify licenses, check reviews, and request references to find a qualified contractor you can trust.

Some things to look for in a good knob and tube wiring replacement contractor include:

• Extensive experience and knowledge about knob and tube wiring and older electrical systems.
• Strong understanding of the National Electrical Code requirements.
• Availability to pull any necessary permits for the work.
• Insurance coverage protecting your home during electrical work.
• Great references from prior electrical rewiring jobs.
• Detailed quote clearly outlining the scope of work, timeline, materials, and total costs.

Full Rewiring Process and What to Expect

The process of completely rewiring your home with modern wiring in place of knob and tube will involve:

Preparation Work

• Electrical contractor conducts thorough inspection of your existing knob and tube wiring system to design new wiring system.

• Contractor develops a detailed rewiring plan for your approval, ensuring compliance with electrical code.

• Permits are pulled with the local building department if required.

• Prepare home by clearing access to walls and ceilings where new wires will be run.

Wiring Installation Process

• All old knob and tube wiring is entirely removed back to the main electrical panel.

• New wiring circuits are routed throughout the home inside the walls, ceilings, and basement/crawlspace.

• Modern non-metallic sheathed NM electrical cable is used for all new wiring.

• Installation of new electrical panel/service with sufficient capacity for the home's needs.

• All new receptacle, switch, and junction boxes are installed and wired.

• Dedicated circuits are installed for major appliances like AC units, washer/dryer, and kitchen appliances as required.

• Appropriate GFCI and AFCI protection included as required by code.

• Proper grounding provided on all circuits.

Completing the Project

• Electrical inspector inspects work and gives approval.

• Walls and ceilings are patched up and repainted.

• Electrical contractor labels all circuits and provides homeowner with detailed circuit breaker panel labels.

• Homeowner receives warranty on work completed.

• Any old wiring that was inaccessible is thoroughly checked in the future when access is available.

Estimated Costs and Factors Affecting Rewiring Cost

The cost to completely rewire an average home generally ranges from $8,000 to $15,000 on average. However, many factors affect the total costs:

• House size - Larger homes require more wire and labor to rewire.

• Wall construction - Easier access inside open walls/attics reduces labor time versus closed walls.

• Degree of demolition/repair needed - Opening and repairing walls adds labor costs.

• Number of circuits required - More individual circuits equals higher material costs.

• Electrical panel upgrade needs - Upgrading the main panel and service adds substantial costs.

• Additional electrical upgrades - Added costs for extra fixtures, outlets, switches, etc.

• Contractor hourly rates which vary by region.

Get multiple quotes to compare pricing, but ensure the estimates all cover the same scope of work. Avoid unrealistically low bids.

Is It Worth Rewiring Your Home?

Given the safety risks, limitations, and headaches associated with antiquated knob and tube wiring, investing in a full rewiring should be strongly considered for most homes.

Though it is a major project requiring sizeable short-term costs, a home rewire provides:

• Greatly improved safety - Eliminating serious electric shock and fire hazards.

• Peace of mind - Enjoy reliable, high-quality power throughout your home. No more flickering lights or tripped circuits!

• Increased home value - Buyers are wary of older wiring systems. Rewiring shows major updating.

• Insurance eligibility - Many insurers require rewiring to continue coverage.

Carefully weighing these meaningful benefits versus the investment costs often makes full rewiring the wise choice to protect your home, family, and financial investment in your property long-term. An electrical contractor can help advise you on the right decision in your specific situation.

Final Thoughts

While rewiring a home with modern wiring in place of old knob and tube wiring represents a major undertaking and expense for a homeowner, it is likely one of the most meaningful upgrades you can make.

Taking the step to rewire provides substantial safety and peace of mind benefits for many decades to come. By using a trusted professional contractor familiar with the intricacies of knob and tube systems, you can feel confident the job will be done properly to meet all electrical codes and safety standards.