How Much Does Knob and Tube Wiring Replacement Cost?
Last Updated on September 18, 2024
Written by CPA Alec Pow | Content Reviewed by CFA Alexander Popinker
Knob and tube wiring was commonly installed in homes built before the 1940s. This outdated electrical system lacks modern safety features and is considered a fire hazard. Replacing knob and tube wiring is an important upgrade for older homes, but how much does it cost?
In this guide, we’ll break down the typical costs of replacing knob and tube wiring in the average home. We’ll look at the dangers of old knob and tube systems, factors that influence replacement costs, hiring an electrician, and if insurance covers any of the costs.
How Much Does Knob and Tube Wiring Replacement Cost?
Knob and tube replacement costs span from $5,000 to $10,000 on average depending on home size. High-end costs reach $15,000 to $25,000.
Based on the above factors, typical pricing averages for replacing knob and tube wiring fall into these ranges:
Small Homes Under 1,500 sq ft
- Labor: $3,000 – $5,000
- Materials: $1,000 – $2,000
- Permits: $500 – $1,000
- Misc. repairs: $500 – $1,500
Total: $5,000 – $10,000
Mid-Size Homes 1,500 – 3,000 sq ft
- Labor: $5,000 – $10,000
- Materials: $2,000 – $4,000
- Permits: $750 – $1,500
- Misc. repairs: $1,000 – $3,000
Total: $8,000 – $15,000
Large Luxury Homes Over 3,500 sq ft
- Labor: $10,000 – $15,000
- Materials: $4,000 – $8,000
- Permits: $1,000 – $2,000
- Misc. repairs: $2,000 – $5,000
Total: $15,000 – $25,000+
Many factors may increase costs further, like challenging access, requiring asbestos abatement, or extensive wall repairs. Get multiple electrician bids for your specific project.
According to Angi, the average cost to replace knob and tube wiring is $24,300, with a typical range between $12,000 and $36,600. They note that the cost can vary significantly based on factors such as home size, accessibility of the wiring and panels, labor fees, permits, repairs, and electrical upgrades.
Similarly, Yahoo Lifestyle reports that the national average knob and tube wiring replacement cost is $24,300, as reported by Angi. They emphasize that while the price may be a higher investment than expected, the benefits of upgrading to a modern electrical system include improved safety, energy efficiency, decreased energy costs, and enhanced home salability.
Bob Vila provides a breakdown of the costs, stating that the average cost to rewire a house with knob and tube wiring is $24,300, with a typical range from $12,000 to $36,600. They also mention that the type of gas fireplace chosen and the existing setup will significantly influence the total cost.
Networx offers a more conservative estimate, stating that the cost to replace knob and tube wiring is typically somewhere between $4,250 and $9,000+ for a 2-story home, with an additional $2,000 for each additional story. They emphasize that replacing this outdated wiring system with a modern wiring system can save time, money, and energy in the long run.
Inch Calculator reports that the national average to remove and rewire knob and tube wiring is $12,000 to $36,000, with general costs ranging from $10 to $20 per square foot. They also mention that the precise cost can vary significantly based on factors such as the size and complexity of the home, the amount of wiring that needs to be replaced, the cost of labor in the area, and the skill of the electricians.
What is Knob and Tube Wiring?
Knob and tube wiring was common in homes built from the 1880s into the 1930s. It consists of insulated copper wires run through ceramic knobs and tubes between walls, ceilings, and attics. Here is a more detailed explanation of old knob and tube electrical systems:
- Two or more wires pass through porcelain insulating tubes or knobs.
- Wires are separated from combustible surfaces by air space.
- Fabric or rubber insulates the wiring itself.
- No ground wires are present.
- Overcurrent protection relies on primitive fuses.
- Wiring is secured by staples and spliced at junction boxes.
This method of electrical wiring was perfectly adequate for the simple lighting and appliance needs at the turn of the century. However, knob and tube wiring lack any modern protective measures.
Risks of Knob and Tube Wiring
While common and normal in old houses, knob and tube wiring has severe deficiencies by modern safety standards. The risks include:
Fire Hazards
The old degraded insulation easily cracks and frays after 50+ years, exposing copper wiring to combustible surfaces. Arcing, sparks, and overheating fires are much more likely in knob and tube systems. According to the U.S. Consumer Product Safety Commission, over 30,000 fires originate from failures with knob and tube wiring every year.
Electrocution Risk
Without a ground wire, knob and tube systems do not provide a safe path for fault currents. Any electrical short goes directly through the body. Modern GFCI outlets also cannot be installed to protect against lethal shocks.
Inadequate for Modern Electrical Loads
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Light bulbs and toasters were the extent of electrical use in the early 1900s. Today’s homes have far greater demands from large appliances, AC systems, home electronics, and more. The overloaded electrical circuits easily overheat, sparking fires.
Outdated Materials and Insulation
While rubber and fabric insulation seemed adequate in the early 1900s, it has long deteriorated after 50-100 years. Cracked damaged insulation exposes dangerous live wires. Insulation materials have also hardened, becoming a combustion risk.
Does Not Meet Any Electrical Codes
Modern electrical codes require safety features like circuit breaker panels, adequate wire gauges, grounding wires, and GFCI outlets in moisture-prone areas. Knob and tube wiring lacks these essential safety provisions, making it illegal under current codes.
Clearly, knob and tube wiring has no place in modern homes with much greater electrical needs. It presents serious dangers that require complete replacement.
Factors That Determine Replacement Costs
Many variables determine the overall budget for removing old knob and tube wiring in a home. Main factors include:
Home Size
Larger homes require more wiring feet, junction boxes, breakers, and labor hours, increasing project pricing. Rewiring costs scale up with home size.
Wiring Accessibility
If wiring is easily accessed through basements, attics, and crawlspaces, costs are lower than buried wires inside walls that require extensive demolition.
Degree of Replacement
In some cases, only certain circuits may need replacement if newer wiring upgrades exist. Complete home rewiring is more expensive.
Labor Rates
Electrician hourly rates range $50 – $150 per hour based on your geographic area and local union rates. Labor is a major cost.
Material and Parts Costs
New copper wiring, improved insulation, junction boxes, conduit, panelboards, breakers, and other parts add up.
Permitting and Inspections
Many jurisdictions require obtaining permits and passing inspections when rewiring, adding costs.
Additional Repairs
Wall demolition, drywall patching, removing old insulation, and repairs from wiring access will increase project prices.
Contingency and Rework
It’s wise to add at least 10% contingency for potential unforeseen costs during rewiring.
Considering these cost factors will help you form an accurate knob and tube rewiring budget.
How Labor Rates Impact Rewiring Costs
Since running new wires is labor-intensive, electrician hourly rates are a major portion of total knob and tube replacement costs. Typical electrician rates average:
$50 – $70 per hour
- Smaller rural communities
- Less experienced electricians
$70 – $90 per hour
- Midsize suburbs
- Semi-retired electricians
$90 – $120 per hour
- Major metro areas
- Union electricians
$120 – $150 per hour
- Large cities like NYC, San Francisco, Chicago
- Top firms with extensive experience
With labor comprising 50% – 70% of typical wiring projects, local electrician rates significantly sway overall pricing. Factor this into budgeting.
How to Find an Electrician for Rewiring
Making sure to hire a fully licensed, insured electrician with extensive knob and tube replacement experience is crucial for both safety and controlling your project’s total costs.
Here are tips for finding a qualified electrician:
- Check reviews for local electricians mentioning knob and tube rewiring.
- Ask your local permitting office for licensed electrician referrals.
- Talk to any neighbors who have completed rewiring projects.
- Verify state licensing, insurance certificates, and bonding.
- Evaluate experience with older home wiring specifically.
Once you identify quality candidates, have them walk through your home to provide a detailed project bid with clearly outlined scopes of work, material costs, labor hours, permit fees, and total fixed pricing.
Avoid any contractors unwilling to fully itemize project pricing upfront. This protects you from massive budget overages down the road.
Home Insurance Coverage
The typical homeowner’s insurance policy considers electrical system upgrades like rewiring as elective remodeling projects, not urgent repairs required due to damage.
However, if your insurance provider has demanded replacing knob and tube wiring to either qualify or continue covering your home, you may be able to convince them to offset some of the replacement costs.
Some approaches for seeking insurance reimbursement include:
- Filing wiring replacement as a required hazard mitigation measure.
- Submitting your electrician quote and invoice showing you completed the demanded wiring upgrades.
- Providing evidence of past wiring damages like smoke or fire incidents.
- Noting if rewiring was required by local code or inspection officers.
While never guaranteed, it’s worth negotiating with your insurer to potentially have some rewiring costs covered, especially if otherwise you will lose your home’s coverage.
Modern Alternatives to Outdated Wiring
When removing old knob and tube wiring, professional electricians typically install new electrical systems using these safer modern materials:
Copper Wiring
- Most common replacement wiring due to high durability and conductivity.
- Typically installed in plastic or rubber sheathing for insulation.
- Different gauge wires used for circuits based on electrical load.
Conduit
- Protective tubing housing wire runs and connections.
- Rigid galvanized piping often used between floors and walls.
- Flexible plastic conduits connect fixtures in accessible spaces.
Junction Boxes
- Safely enclose wiring connections and branching.
- Electrical code mandates maximum distances between boxes.
- Specific exterior or humidity-resistant boxes used where needed.
Circuit Breaker Panel
- Replaces outdated fuse boxes with individual breakers per circuit.
- Provides modern overload and short circuit protection.
- Rating matched to home’s total electrical service capacity.
Modern wiring materials provide the level of safety that old knob and tube wiring lacks.
Dangers of DIY Knob and Tube Replacement
Considering typical replacement costs, some homeowners contemplate DIY knob and tube wiring projects to save on electrician labor fees. However, this poses grave dangers:
Electrocution Hazards – Mistakes working with live wiring can easily kill you or loved ones. Proper training is essential.
Burn Hazards – Accidental arcs and sparks from wires can ignite fires inside walls and ceilings.
Improper Connection and Splicing – Faulty terminations create “invisible” hazards down the road.
Damage to Electrical Components – Lack of experience risks destroying wires, junction boxes, and other parts.
Violating Code Requirements – DIY work often fails to meet safety rules and inspection compliance.
Liability Issues – You assume full liability for any injuries, fires, or issues with DIY electrical work.
No Insurance Coverage – Issues from DIY wiring may jeopardize future home insurance coverage.
Considering the core safety risks, only trained professional electricians should handle complex knob and tube replacement projects. DIY attempts simply aren’t worth the massive risks involved.
Final Words
Replacing aging, dangerous knob and tube wiring should be a top priority for any homeowner with this outdated system. On average, rewiring a standard 2,000 sq ft home costs $5,000 to $15,000 depending on accessibility, local electrician rates, and necessary repairs.
While not a small project, modern electrical systems greatly improve home safety, insurability, and value. The project cost serves as an excellent investment. Identify any knob and tube wiring and budget for replacement. Consult with qualified electricians to map out a plan for a much-needed wiring upgrade.
Frequently Asked Questions
How important is it to replace knob and tube wiring?
Replacing knob and tube wiring is extremely important for home safety. This outdated wiring lacks essential protective grounding and insulation. It poses serious electrocution, fire, and short circuit risks. Upgrading to modern wiring should be a top priority.
How do I know if my knob and tube wiring has been replaced?
Check your electrical panel for wiring labeled with rubber or plastic insulation rather than fabric wrapped wiring. Also look for gauges printed on insulation and a grounding wire. Open accessible areas like basements and attics to check for ceramic knobs, metal tubes, and braided wiring which indicate knob and tube systems.
How long does it take to replace a knob and tube?
For a standard 2,000 sq ft home, most electricians estimate 1-2 weeks to fully replace old knob and tube wiring throughout the home. However, difficult access points can lengthen the project to 4 weeks or more. Schedule your electrician according to a reasonable project timeframe for your home’s specific needs.
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