Upgrade Your Home with Knob and Tube Wiring

What is Knob and Tube Wiring?

Knob and tube wiring is an early method of electrical wiring used in homes and buildings in North America from about 1880 to the 1940s. It consists of separate rubber-insulated copper conductors run within wall cavities, with porcelain knobs fastening the wires to framing and porcelain tubes covering any splices.

While knob and tube wiring was an improvement over earlier systems, it has some drawbacks compared to modern wiring methods:

• No ground wire for safety. Relies on metal conduit for grounding.
• Wires run through open spaces rather than protective conduit. More prone to damage.
• Only designed for smaller loads, not large appliances.
• Can deteriorate over time, becoming brittle and cracked.

Many homes still contain original knob and tube wiring. This old wiring can present safety issues and may not be sufficient for modern electrical usage.

Why Knob and Tube Wiring Should Be Upgraded

Here are some key reasons to consider upgrading knob and tube wiring in your home:

• Fire hazard - The brittle, cracked insulation can allow wires to arc and spark, which can ignite nearby combustible materials. Knob and tube has a higher fire risk than modern wiring.
• Insufficient capacity - Knob and tube was only designed for smaller electrical loads. Running modern high-wattage appliances on it can be dangerous.
• No grounding - Lack of a ground wire means risk of electric shock and damage to sensitive electronics.
• Insurance issues - Many insurance companies won't insure a home with knob and tube wiring due to the risks.
• Resale value - Knob and tube wiring can make it difficult to sell a home. Upgrading can greatly improve resale value.
• Peace of mind - Replacing knob and tube removes a source of constant worry about electrical fires and shocks.

In most cases, the benefits of increased safety and capacity are well worth upgrading from this obsolete wiring method.

Options for Upgrading Knob and Tube Wiring

If your home has knob and tube wiring, here are typical options for upgrades:

• Full rewire - The most thorough option. All old wiring is removed and replaced with modern wiring meeting current code. This ensures the entire home's electrical system is safe and meets capacity needs.

• Pigtailing - The old wiring is left in place but new grounded wires are spliced (pigtailed) to the old. Provides grounded outlets but doesn't increase capacity.

• Circuit breaker panel upgrade - The main service panel is upgraded to a higher amperage capacity. Allows powering more outlets and appliances.

• Individual circuits - Specific circuits are rewired room-by-room as needed. Lower upfront cost but piecemeal.

• Leave as-is - Knob and tube can be left in place as long as no major changes are needed. It should be inspected regularly by an electrician. But risks remain.

I recommend consulting with a qualified electrician to determine the best scope of work for your unique needs. Safety should be the top priority.

Cost to Upgrade Knob and Tube Wiring

The cost to upgrade wiring depends on factors like:

• Home size - More square footage means more wiring to replace.

• Scope of work - A full rewire is most expensive. Targeted upgrades are cheaper.

• Accessibility - Easier access to wiring cuts costs. Fishing new wires through finished walls is time-consuming.

• Local electrician rates - Get multiple quotes to find the best rate.

As a ballpark estimate, expect to pay:

• Full rewire of a 2,000 sq ft home: $8,000 - $15,000

• Rewire one circuit: $500 - $1,000

• Breaker panel upgrade: $1,500 - $3,000

• Pigtailing outlets: $75 - $150 per outlet

Upgrading wiring is a major project, but pays off through increased home safety, value, and electrical capacity. With smart planning, it can be done in phases to fit your budget.

Safety Tips for Existing Knob and Tube Wiring

If you aren't able to upgrade wiring right away, here are some tips to manage safety risks of knob and tube wiring:

• Have an electrician evaluate the condition and current usage.

• Avoid overloading circuits with high-wattage appliances.

• Don't run extension cords on old wiring.

• Use bulbs with appropriate wattage in fixtures.

• Inspect often for cracking, charring, warm spots.

• Keep wiring free of insulation contact.

• Have an ABC fire extinguisher handy just in case.

• Turn off unused circuits at the breaker panel.

• Don't run new wiring alongside old.

While stopgap measures help, upgrading old knob and tube wiring remains the best long-term solution. Prioritize safety and don't ignore those small warning signs of electrical issues. With smart upgrades, you can bring your home's wiring fully up to modern standards.