Cost to replace knob and tube wiring
Ashburn, VA

Cost to replace knob and tube wiring

Ashburn, VA

Cost to replace knob and tube wiring

$8 – $17average cost per square foot
$12,000 – $35,000average total cost to replace

Get free estimates for your project or view our cost guide below:

$8 – $17 average cost per square foot

$12,000 – $35,000 average total cost to replace

Get free estimates for your project or view our cost guide below:
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Tara Farmer
Written by
Tara Farmer
Edited by
Kristen Cramer
Fact-checked by
Tom Grupa

Knob and tube wiring replacement cost

The cost to replace knob and tube wiring is $12,000 to $35,000 on average, or $8 to $17 per square foot, depending on the home size, number of circuits, and wiring accessibility. Knob and tube wiring replacement often requires upgrading the service panel and adding more outlets, switches, and fixtures.

Average cost to replace knob and tube wiring - Chart
Average cost to replace knob and tube wiring - Chart
Cost to replace knob and tube wiring
Home square footage Average cost
1,000 $8,000 – $17,000
1,200 $9,600 – $20,400
1,500 $12,000 – $25,500
2,000 $16,000 – $34,000
2,500 $20,000 – $42,500
3,000 $24,000 – $51,000
3,500 $28,000 – $59,500

Get free estimates from wiring installers near you.

Cost breakdown to replace knob and tube wiring

Knob and tube wiring replacement cost breakdown
Factor Average cost
New electrical panel $800 – $2,500
New wiring materials, outlets, & switches $8,600 – $10,800
Rewiring labor $2,400 – $20,800
Permits $200 – $900
Total cost to replace $12,000 – $35,000

Cost factors for replacing knob and tube wiring include:

  • Home size / number of rooms – Rewiring larger homes requires more labor and materials. Each room adds multiple circuits, outlets, and switches to the project.

  • Accessibility – Rewiring a home without attic, crawl space, or basement access may require opening walls and ceilings, increasing the project time, repair work, and debris removal costs.

  • Temporary relocation – Most electricians recommend staying out of the house during the rewiring project.

  • MaterialsElectrical wiring costs $0.10 to $4.00 per linear foot for the material alone, depending on the type. Other rewiring materials include junction boxes, wire nuts, staples, wall plates, outlets, switches, and fixtures.

  • Finish quality – High end, designer finishes cost much more than standard "builder grade" outlets, switches, and fixtures. When rewiring a whole house, these choices can significantly impact the total project cost.

  • Permits – Electrical rewiring permits cost $200 to $900. Replacing knob and tube wiring requires one or more permits, depending on the location and project scope.

  • Inspections – An electrical inspection costs $100 to $200 to ensure the work is up to code.

  • Repairs – Rewiring a house typically involves making many small holes in the walls and ceilings to fish the new wiring behind the drywall or plaster. Repair costs are much higher in homes without attic, basement, or crawlspace access.

Knob and tube wiring in an older home.
Knob and tube wiring in an older home.

Knob and tube wiring removal cost

Knob and tube wiring removal is typically included in a rewiring estimate. Removing the wiring completely would require opening the walls. Instead, electricians remove only the visible wiring—like in attics or unfinished basements—and "abandon" the remaining disconnected wires concealed within the walls.

Removing knob and tube wiring completely may involve the following associated costs in addition to the extra labor hours:

Upgrade circuit breaker panel

The average cost to replace an electrical panel is $850 to $2,500, depending on the size and number of circuits. Homes with knob and tube wiring often have an old-style fuse box or a low-amp service panel that requires updating to a higher capacity circuit breaker panel.

Labor cost to rewire knob and tube wiring

Hiring an electrician costs $50 to $130 per hour to rewire knob and tube wiring. This hourly rate covers labor only. The added material cost often includes a 20% to 35%+ markup.

Some electricians calculate the cost to rewire a house at a flat rate of $100 to $300+per opening—per outlet, switch, or fixture—which includes labor and materials.

Upgrading outlets, switches, and lights

Replacing knob and tube wiring typically involves updating the outlets, switches, and fixtures. The project may also require adding more outlets to bring the home up to code. Most older homes have one outlet per room, and the National Electrical Code (NEC) now requires a receptacle every 12 feet at minimum.

Knob & tube FAQs

What is knob and tube wiring?

Knob and tube (K&T) wiring is an ungrounded, two wire system with ceramic knobs holding the wires in place, away from wood structures. K&T wiring is covered in thin rubber and cloth sheathing and has ceramic tubes protecting and insulating the wires running through floor joists and wall studs.

K&T wiring was the standard in homes before 1930, and some areas installed it until the 1950s. Existing K&T wiring is not illegal, but it does not meet current electrical and building codes because it is ungrounded and lacks the electrical capacity needed in modern homes.

Is it worth replacing knob & tube wiring?

Replacing knob and tube wiring is worth it to ensure a home's safety, improve its efficiency, and update its capacity to accommodate today's electrical demands. Knob and tube wiring is ungrounded, cannot support heavy-duty appliances, and most knob and tube wired homes have only one outlet per room.

Are there knob and tube removal grants?

Some states offer knob and tube removal grants or interest-free loans if the wiring prevents proper home insulation. Many government assistance programs offer home repair grants or loans to bring older homes up to current safety codes. Eligibility depends on age, income, location, and project scope.

Can you partially replace knob and tube electrical systems?

Yes, you can partially replace knob and tube electrical systems. However, experts recommend replacing the entire system simultaneously when possible because incorrectly connecting to a knob and tube wiring system creates additional safety hazards.

Is knob and tube wiring safe?

Knob and tube (K&T) wiring may be safe if it was installed correctly, has not been tampered with or added to, has never been overloaded, and its conductors are still in good physical condition. Hire an electrical inspector to determine if your home's K&T wiring poses safety risks.

Knob and tube (K&T) wiring may be unsafe for several reasons:

  • Material age – All K&T wiring is 70 to 100+ years old. The thin rubber and cloth sheathing degrades over time, exposing hot wires.

  • No ground wire – K&T wiring contains only a hot and neutral wire, with no ground wire to safely direct excess electricity. Ungrounded wiring is especially unsafe in kitchens, bathrooms, laundry rooms, and outdoors.

  • Insulation – K&T wiring requires space to dissipate heat. Installing insulation in cavities with K&T wiring is a serious fire hazard.

  • Incorrect updates – Electrical upgrades, like adding circuits, made without replacing the K&T wiring pose a fire risk if not installed correctly.

Does knob and tube wiring have to be replaced?

Knob and tube (K&T) wiring does not have to be replaced in all cases. However, some jurisdictions require replacement because the materials degrade over time and create a potential fire hazard.

Most experts recommend replacing K&T wiring to bring the home up to current safety standards and meet modern electrical needs.

Some insurance companies refuse coverage or charge higher premiums if the home has K&T wiring.

Getting estimates from rewiring electricians

Before hiring wiring installers to replace your knob and tube wiring, remember to:

  • Get at least three in-person estimates to compare.

  • Look for electricians specializing in rewiring older homes.

  • Check their reviews on HomeGuide and Google.

  • Hire a licensed, bonded, and insured company that has been in business for 5+ years.

  • Avoid selecting the lowest quote as quality may suffer.

  • Get a detailed contract and warranty in writing before the work begins.

  • Never pay in full before the job is complete. Work out a payment plan instead.

Questions to ask

  • How long have you been in business?

  • Are you licensed, bonded, and insured?

  • What experience do you have replacing knob and tube wiring?

  • Do you offer free estimates?

  • Can you provide references with contact information?

  • Do you handle the permit and inspection process and is it included in the estimate?

  • Will you need to open any walls to rewire the home?

  • Do you bring in a drywall or plaster repair specialist to repair any holes made during rewiring?

  • Is the wall repair included in the estimate?

  • How do you handle the old wiring?

  • What additional costs could come up during the installation?

  • How long will the installation take?

  • Can I live in the house while you are rewiring?

  • Do you offer a warranty? If yes, what does it cover?