How Much Does Knob and Tube Wiring Replacement Cost?

Updated on September 4, 2026 | Written by Alec Pow
This article was researched using 9 sources. See our methodology and corrections policy.

Replacing knob and tube wiring typically costs about $12,000 to $36,000+ for a whole house in 2026. Current estimates put the work at roughly $8 to $20 per square foot, meaning a 2,000-square-foot older home can land around $16,000 to $40,000 before major plaster restoration, painting, asbestos work, or a complicated electrical-service upgrade.

The final cost depends heavily on how much knob and tube is still energized, whether electricians can reach it through an attic or basement, how many new circuits and receptacles are needed, and whether the existing panel and service can support the finished system. Old plaster walls and inaccessible finished ceilings can turn a straightforward electrical job into a much larger restoration project.

Finding knob and tube wiring does not automatically mean every wire in the house must be physically pulled from the walls. A typical rewire disconnects the obsolete circuits, installs new code-compliant wiring, and may leave inaccessible dead wiring abandoned inside closed walls rather than demolishing finishes merely to remove it.

Article Highlights

• Whole-house knob and tube replacement currently averages roughly $12,000 to $36,000+ (at $30 per hour, earning that amount would take about 2.3 to 6.9 months of full-time work, before taxes).
• Current cost guides place the project around $8 to $20 per square foot.
• A 2,000-square-foot house can therefore cost approximately $16,000 to $40,000 for the electrical rewire itself.
• An electrical panel upgrade can add roughly $800 to $4,000 depending on capacity and scope.
• Permits commonly add a few hundred dollars rather than the $1,000+ blanket figures sometimes quoted for these projects.
• Wall, ceiling, plaster, and paint restoration can add thousands after the electrician finishes.
• Existing knob and tube wiring is not automatically illegal everywhere, but damaged, improperly modified, overloaded, or insulation-covered systems can present serious safety and code problems.

How Much Does Knob and Tube Wiring Replacement Cost?

House size	Current planning range	Based on
1,000 sq ft	$8,000 to $20,000 (about 1.5 to 3.8 months of full-time work at $30 per hour)	Current $8–$20/sq-ft estimates
1,500 sq ft	$12,000 to $30,000	Current $8–$20/sq-ft estimates
2,000 sq ft	$16,000 to $40,000	Current $8–$20/sq-ft estimates
2,500 sq ft	$20,000 to $50,000	Current $8–$20/sq-ft estimates
3,000 sq ft	$24,000 to $60,000	Large or difficult homes can exceed the national average

Angi’s August 2026 knob and tube replacement cost guide puts a typical project at $12,000 to $36,600, usually around $10 to $20 per square foot. Its square-foot examples put a 2,000-square-foot home at $20,000 to $40,000.

HomeGuide’s 2026 knob and tube cost data is somewhat lower at $8 to $17 per square foot and an average project range of $12,000 to $35,000. Its 2,000-square-foot example is $16,000 to $34,000.

The overlap between those sources is more useful than one artificial national average. For planning, $12,000 to $36,000+ is a reasonable whole-house starting range, while a larger or difficult property can move past $40,000.

What You’re Paying For

Knob and tube was an early wiring method that ran individual insulated conductors through walls, ceilings, basements, and attics. Porcelain knobs held wires away from framing, while porcelain tubes protected conductors passing through wood.

A modern replacement project does not simply swap old wire for new wire along the same route. The electrician may need to design new branch circuits, install grounded cable, add electrical boxes, replace receptacles and switches, install required GFCI or AFCI protection, reorganize breakers, and bring altered portions of the electrical system into compliance with the locally adopted electrical code.

The work may include:

• Tracing which knob and tube circuits are still active
• Disconnecting obsolete circuits
• Running new grounded branch wiring
• Installing modern electrical boxes
• Replacing two-prong or improperly converted receptacles
• Adding circuits where the old system served too many loads
• Updating breakers and protective devices
• Testing completed circuits
• Permit and inspection work

This labor is why knob and tube replacement costs substantially more than installing wiring in open walls during new construction.

The Hidden Price Is Wall Repair

The electrical quote may not include returning the house to its original appearance. This is particularly important in older homes with plaster and lath walls.

Electricians try to fish new cable through existing cavities and use attics, basements, crawlspaces, closets, and small access openings when possible. Some houses still require substantial cutting.

Current replacement estimates put minor drywall repairs around $300 (about 1.3 full-time workdays at $30 per hour), while larger repair work can reach $900+. HomeGuide reports individual drywall patches at roughly $300 to $1,500+ depending on size and complexity. Historic plaster can be more labor-intensive.

Painting is another separate bill. Angi’s current estimate gives an average whole-interior painting cost around $1,960.

Mini case 1: Suppose a 2,000-square-foot house receives a $25,000 electrical quote, followed by $2,000 of plaster repair and $2,000 of painting. The true renovation cost becomes $29,000, meaning finish restoration added 16% to the electrician’s price.

Ask every bidder whether cutting, patching, plaster repair, texture matching, trim work, and painting are included or excluded.

Does the Panel Need Replacement?

A knob and tube rewire often reveals an old electrical panel or undersized service, but a new panel is not automatically required merely because knob and tube exists.

HomeGuide currently estimates a new panel at roughly $800 to $2,500 within a knob and tube project. Angi gives a wider potential range of about $600 to $4,000 depending on the work required.

A small older house may have a 60-amp or 100-amp service that cannot comfortably accommodate today’s appliance loads or the new circuit layout. Other properties may already have a newer 200-amp panel installed during an earlier renovation.

Mini case 2: Take a $30,000 rewire and add a $2,500 panel upgrade. The project rises to $32,500. Add another $3,000 for wall and paint restoration and the homeowner is now budgeting $35,500.

Our guide to electrical panel upgrade costs covers panel capacity, service changes, labor, and permit expenses separately.

The Quote Trap

Two electricians can quote very different totals while both prices are technically accurate because their scopes are different.

A low quote may cover only replacing energized knob and tube branch circuits. A larger quote may include a new panel, added receptacles, new appliance circuits, smoke-alarm wiring, code-required protective devices, permits, inspections, and coordination with wall repair.

Before comparing bids, ask whether each price includes:

• All energized knob and tube circuits
• New receptacles and switches
• Dedicated kitchen, laundry, HVAC, or appliance circuits
• Panel replacement or breaker changes
• GFCI and AFCI protection where required
• Permit and inspection fees
• Attic, basement, and crawlspace work
• Wall and ceiling openings
• Drywall or plaster repair
• Painting
• Debris removal

A $20,000 electrical-only proposal can become more expensive than a $25,000 proposal that includes more of these items.

Old Wiring Is Not Illegal

Knob and tube is obsolete for normal new residential construction, but saying that every existing installation is automatically illegal under modern electrical codes is inaccurate.

National Electrical Code Article 394 still addresses concealed knob and tube. Current local requirements vary because states and municipalities adopt and amend electrical codes differently.

One particularly serious issue is thermal insulation. EC&M’s explanation of NEC Article 394 requirements notes that concealed knob and tube generally cannot be used in wall, ceiling, or attic spaces where loose, rolled, or foamed insulation envelops the conductors.

There can be local amendments. Washington, for example, has a specific knob and tube insulation rule allowing certain insulation around existing wiring only when several conditions are met, including inspection and written certification by an appropriately licensed electrical contractor.

That is why a homeowner should ask the electrician which locally adopted code applies rather than relying on a blanket statement from a national article.

What Makes Knob and Tube Risky?

The Electrical Safety Foundation International identifies knob and tube as an older ungrounded wiring method that can become hazardous through aging, damage, and faulty renovations. Its older-home electrical guidance recommends professional evaluation rather than assuming an old electrical system is safe based solely on whether it still works.

The U.S. Consumer Product Safety Commission studied electrical fires involving older residential wiring and found knob and tube failures associated with conditions such as overfusing, overloaded circuits, unsafe extensions, and wiring surrounded by thermal insulation.

The CPSC’s residential electrical fire research does not support the claim that knob and tube causes 30,000 fires every year. That statistic should not be attributed specifically to knob and tube.

The conditions that deserve attention include:

• Cracked or missing conductor insulation
• Improper extensions using newer cable
• Oversized fuses or breakers
• Overloaded circuits
• Loose or amateur splices
• Wiring buried in thermal insulation where prohibited
• Missing equipment grounding
• Evidence of overheating or arcing

ESFI recommends an electrical inspection for homes 40 years old or older and when purchasing a previously owned home.

Can GFCI Work Without a Ground?

Yes. The absence of an equipment grounding conductor does not mean a GFCI cannot operate.

NEC guidance summarized by EC&M explains that an existing two-wire nongrounding receptacle can be replaced with a GFCI receptacle marked “No Equipment Ground,” or with a grounding-type receptacle protected by GFCI and properly labeled.

The GFCI replacement rules specifically note that GFCI protection functions on a two-wire circuit without an equipment grounding conductor because the ground conductor is not required for the GFCI’s sensing operation.

A GFCI does not create an equipment ground. It provides shock protection by detecting current imbalance. Whether a particular old circuit should remain in service is a separate question for the electrician.

Our guide to GFCI outlet installation costs covers the price of installing or replacing these protective devices.

Insurance

Homeowners insurance can make knob and tube an urgent financial issue, but that does not mean the insurer normally pays to replace it.

Allstate’s guidance for older homes says knob and tube can lead to higher premiums or denial of coverage and notes that many insurers will not cover a house containing this wiring.

An insurer may ask for replacement as a condition of writing or renewing a policy. That is usually a maintenance or eligibility requirement, not an insured loss.

If a covered event such as a fire damages electrical wiring, the resulting claim is a different issue and depends on the policy, cause of loss, exclusions, and settlement terms. Do not assume that describing a planned rewire as “hazard mitigation” turns it into a covered claim.

Get the insurer’s requirement in writing before beginning work and ask exactly what documentation it wants after completion.

What We Verified

Related Electrical Costs

If the rewire also requires more service capacity, compare our current guide to the cost of replacing an electrical panel.

Homes being prepared for backup-power equipment may also need electrical-system upgrades. Our GenerLink installation cost guide covers one common transfer-device option.

For a smaller old-home wiring project, see the current home rewiring cost examples used for manufactured and compact houses.

Answers to Common Questions

How much does it cost to replace knob and tube wiring?

A whole-house replacement commonly costs about $12,000 to $36,000+ in 2026. Current estimates work out to roughly $8 to $20 per square foot.

How much would a 2,000-square-foot house cost to rewire?

Current square-foot estimates produce a range of roughly $16,000 to $40,000. Panel upgrades, difficult access, plaster restoration, painting, and other repairs can push the complete project higher.

Is knob and tube wiring illegal?

Existing knob and tube is not automatically illegal everywhere merely because it is old. Current electrical codes restrict where the wiring can be used, and local amendments differ. Damaged, altered, overloaded, or insulation-covered wiring can require correction or replacement.

Can you put a GFCI outlet on knob and tube wiring?

Yes, an existing ungrounded circuit can use GFCI protection under NEC receptacle-replacement rules when the receptacle is installed and labeled correctly. A GFCI does not create an equipment ground.

Does homeowners insurance pay to replace knob and tube?

Usually not when replacement is simply maintenance or a condition for obtaining coverage. Some insurers may refuse to insure a house until the wiring is replaced. Coverage for wiring damaged by a separate covered event depends on the policy and circumstances.

Does every old knob and tube wire have to be removed from the walls?

Not necessarily. Electricians commonly disconnect obsolete circuits and leave inaccessible dead wiring abandoned inside closed wall cavities rather than opening every wall solely to pull it out. Accessible wiring may be removed as part of the project.

How long does knob and tube replacement take?

A whole-house project often takes roughly one to three weeks for the electrical work, depending on house size, access, circuit count, inspection scheduling, and whether panel or service work is included. Plaster and paint restoration can extend the total renovation schedule.

Disclosure: Electrical codes, permit requirements, insurance rules, and acceptable treatment of existing knob and tube wiring vary by jurisdiction and property. Have a licensed electrician inspect the actual system and confirm local requirements before altering it.