Knob and tube wiring was commonly installed in homes built before 1930. While it served its purpose for decades, this outdated system can be dangerous by today's electrical standards. Replacing knob and tube wiring entirely is the only way to make your home's electrical system truly safe. This in-depth guide will walk you through the full process of replacing knob and tube wiring safely.
Dangers of Knob and Tube Wiring
Knob and tube wiring lacks many modern safety features that are standard in modern electrical systems. Here are some of the main risks posed by knob and tube wiring:
Fire Hazard
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The insulation on old knob and tube wiring easily cracks and deteriorates over time. This exposes the conductor wires and can cause short circuits, sparks, and fires.
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Knob and tube circuits lack grounding. This makes them more likely to overload and overheat.
Electrical Shock Risk
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Damaged or deteriorated areas of insulation can enable the wire to energize metal electrical boxes and fixtures in your home. This can lead to dangerous electrical shocks.
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Old wiring is often spliced together in "...chaotic, dangerous ways" according to electrical safety experts. This increases the chances of faults.
Inability to Support Modern Electrical Loads
- Lighting and appliances have much higher electrical demands today. Knob and tube wiring lacks the capacity to handle the load from modern devices.
Insurance Issues
- Many insurance companies won't issue policies for homes with knob and tube wiring due to the substantial fire risk.
Why Complete Replacement is Necessary
Some homeowners consider repairing sections of damaged knob and tube wiring rather than replacing the entire system. However, experts strongly warn against this.
Partial repairs on old wiring are considered unreliable and unsafe. The CPSC and Consumer Reports recommend complete removal and replacement of knob and tube wiring for the following reasons:
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You can't identify all risky areas visually. Much of the wiring is inside walls and difficult to inspect thoroughly. Any sections left behind will continue to degrade.
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Partial replacement creates inconsistencies. Mixing modern wiring with old can cause improper connections and overloaded circuits.
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Safety requires a fully grounded system. Grounding knob and tube wiring is extremely difficult, if not impossible in most homes.
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Insurance requires full replacement. Companies will still consider the home to have unacceptable knob and tube wiring if any of it remains.
The consensus among electricians and home safety experts is that complete replacement of the old wiring system is the only lasting solution. I strongly recommend fully replacing knob and tube wiring for significantly improved safety.
Finding a Qualified Electrician
Replacing your home's electrical system is highly complex. It should only be done by a licensed electrician experienced in safely removing old knob and tube wiring.
When hiring an electrician, make sure to:
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Verify their license is current in your state. Most states provide license lookup on their electrical board website.
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Only consider electricians who are bonded and insured. This protects you from liability. Request documentation.
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Check reviews and references. Ask trusted friends for recommendations and read reviews online.
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Get multiple quotes. Compare theScope of work and total costs from at least 3 electricians.
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Choose one who specializes in old wiring replacement. Ask specifically about their experience with knob and tube removal.
Overview of the Replacement Process
Replacing the entire knob and tube wiring system in a home is a major undertaking. The general process involves:
Initial Inspection and Planning
- The electrician will thoroughly survey your home's wiring and plan the details of the project.
Install New Electrical Panel
- A new, modern panel must be installed to handle additional circuits.
Running New Wiring
- All old wiring is removed. New wires are run through walls and ceilings to each light, switch, and receptacle.
Installation of GFCIs
- GFCI (ground fault circuit interrupter) outlets provide important modern shock protection.
Removing Old Accessories
- Knob and tube era boxes, switches, fixtures, etc are replaced with modern safe versions.
Testing and Certification
- The system is thoroughly tested. A certificate of approval is issued when the work passes inspection.
Proper planning, skilled installation, and attention to safety are crucial in knob and tube replacement. Rushing the job or cuting corners risks creating major hazards.
Cost and Timeframe
The cost and timeframe to replace knob and tube wiring depends on factors like:
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Size and layout of your home
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Accessibility to wiring runs
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Number of circuits
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Geographic location
As a general guideline, you can expect:
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Total Cost: $8,000 to $15,000
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Duration: 2 to 3 weeks
Getting multiple quotes is the best way to estimate costs for your specific home. Adding wiring upgrades at the same time (like wiring for ceiling fans) may increase cost but can be worthwhile.
Budget appropriately and consider the project an important safety investment. The value and safety gains are well worth the cost.
Summary of Key Points
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Knob and tube wiring is considered obsolete and dangerous by today's standards. The risks include fire, shock, and inability to support modern electrical loads.
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Partial repair or replacement is strongly discouraged. For full safety, the entire system should be removed and replaced.
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Hire a licensed, bonded, insured electrician experienced in knob and tube replacement. Get multiple quotes.
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Complete replacement involves installing new wiring, outlets, switches, electrical panel, and fixtures. Proper planning and installation techniques are vital.
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Total costs typically range from $8,000 to $15,000, and may take 2-3 weeks to complete. View the project as a home safety investment.
Replacing knob and tube wiring is a major undertaking, but brings your home's electrical system up to modern safety standards. Take the time to hire the right electrician and budget appropriately. The peace of mind of safe and reliable wiring is well worth the effort.