Knob-and-Tube and Aluminum Wiring in Insurance Claims: When a Covered Loss Reveals Outdated Electrical

Knob-and-tube (K&T) wiring was the standard residential electrical installation method from the 1880s through the 1940s. Aluminum branch circuit wiring was widely used from roughly 1965 through 1975, when copper prices spiked. Both wiring types are legal to leave in place in an existing home — no California regulation requires a homeowner to proactively replace them. But when a covered loss — fire, water, falling tree, vehicle impact — damages your home and the resulting repairs require opening walls, ceilings, or attic spaces, the electrician discovers what has been hidden for decades. And once the walls are open, the California Electrical Code requires that the exposed wiring be brought to current standards before the walls are closed again.

This is structurally identical to the asbestos and lead paint situation: the hazardous or non-compliant condition existed before the loss, but the obligation to address it arose solely because the covered loss triggered repairs that exposed it. The additional cost is part of the repair, and the insurer is responsible for paying it.

Where Knob-and-Tube and Aluminum Wiring Are Found

Knob-and-Tube Wiring

K&T wiring is found primarily in homes built before 1950. In California, this includes huge numbers of homes in Los Angeles, San Francisco, Oakland, Berkeley, Pasadena, Long Beach, and other cities with pre-war housing stock. K&T wiring runs individual hot and neutral conductors along ceramic “knob” insulators attached to framing members, passing through framing via ceramic “tube” insulators. The wiring has no ground conductor — a critical deficiency by modern standards. It was designed to be air-cooled, running through open spaces between framing with adequate ventilation around the conductors.

The system worked acceptably in its era. But modern electrical loads far exceed what K&T circuits were designed to carry, and the rubber and cloth insulation on the conductors degrades over time, becoming brittle and cracked. The most dangerous condition arises when insulation (fiberglass, cellulose, or blown-in foam) has been added around K&T wiring, which was never designed to be enclosed. The insulation traps heat around conductors that were engineered for air cooling, creating a fire risk.

Aluminum Branch Circuit Wiring

Aluminum branch circuit wiring (as distinguished from aluminum service entrance cable, which is standard and not problematic) was used in single-family homes from approximately 1965 through 1975. In California, this corresponds to a massive wave of suburban construction — tract homes in the San Fernando Valley, Orange County, the Inland Empire, and the San Diego suburbs. Aluminum wiring is found in an estimated 2 million homes nationwide.

The issue with aluminum branch circuits is not the wire itself but the connections. Aluminum expands and contracts more than copper when heated and cooled (a property called differential thermal expansion). Over time, this loosens connections at outlets, switches, and splices, creating resistance and heat buildup. The Consumer Product Safety Commission (CPSC) has found that homes with aluminum wiring are 55 times more likely to have connections reach fire-hazard conditions than homes with copper wiring.

How a Covered Loss Triggers Electrical Code Requirements

The California Electrical Code (Title 24, Part 3, based on the National Electrical Code, NFPA 70) governs all electrical work performed in the state. The key principle is that any new electrical work must comply with the current code in effect at the time the work is performed. When a covered loss requires repairs that involve opening walls and disturbing or replacing electrical components, the permit and inspection process requires that the new and altered work meet current code.

Knob-and-Tube: Cannot Be Buried in Insulation

NEC §394.12 prohibits new K&T installations entirely. More critically for claims purposes, NEC §394.12(B) prohibits K&T wiring in hollow spaces where it is “concealed by insulation,” and the California Electrical Code enforces this provision. When a fire or water loss requires replacing insulation in walls or attic spaces where K&T wiring is present, the wiring must be replaced before new insulation can be installed. You cannot legally insulate around K&T wiring. The electrician must either remove and replace the K&T circuits in the affected areas or reroute them so they are not enclosed in insulation.

This is not an optional upgrade. The building inspector will not sign off on the repair if K&T wiring remains buried in new insulation. The repair cannot be completed without addressing the wiring. Therefore, the wiring replacement is a necessary cost of the covered repair.

Aluminum Wiring: CO/ALR Devices and COPALUM Remediation

When repairs expose aluminum branch circuit connections, the California Electrical Code requires that any altered or new connections comply with current standards. Standard copper-only devices cannot be used on aluminum circuits — they require CO/ALR-rated (Copper-Aluminum Revised) outlets, switches, and connectors, or the CPSC- recommended COPALUM crimp connector system that uses a special tool to permanently attach a copper pigtail to each aluminum conductor. If the scope of the covered repair involves replacing outlets, switches, or junction boxes on aluminum circuits, the replacement devices must be aluminum-compatible, and the electrician may recommend or the inspector may require pigtailing the entire affected circuit for safety.

Who Pays: The Insurer, Because This Is a Repair Cost

The insurer owes the cost of repairing your home after a covered loss. The cost of repairing your home includes every cost that is legally required to complete the repair. If the California Electrical Code requires rewiring before the walls can be closed and the repair can pass inspection, that rewiring cost is part of the repair cost — not an optional improvement.

A contractor cannot legally close walls over K&T wiring buried in new insulation. An electrician cannot legally install standard copper-only devices on aluminum branch circuits. These are not choices. They are code requirements triggered by the repair work the covered loss necessitated. The additional cost exists solely because of the covered loss.

Ordinance or Law Coverage

If your policy includes ordinance or law (O&L) coverage, electrical code upgrade costs are a textbook application of that coverage. O&L coverage exists to pay the increased cost of repair caused by the enforcement of building codes, ordinances, or regulations that apply only because the repair work triggers them. Before the loss, you had no obligation to rewire your home. After the loss, the California Electrical Code requires that the exposed and affected wiring be brought to current standards as a condition of completing the repair. This is exactly the scenario O&L coverage is designed for.

Even without a separate O&L endorsement, rewiring costs caused by a covered loss are arguably part of the base Coverage A repair cost. The repair cannot legally be completed without addressing the wiring. But having O&L coverage provides a second, independent basis for recovery and eliminates any ambiguity about whether code compliance costs are covered.

Common Carrier Tactics for Avoiding Electrical Upgrade Costs

1. “It’s Pre-Existing”

The carrier argues that the K&T or aluminum wiring existed before the loss and is not “caused by” the covered peril. This is the same flawed argument carriers use for asbestos and lead paint. Yes, the wiring was there before the loss. But there was no obligation to replace it. The replacement obligation arose only because the covered loss opened the walls and triggered code compliance requirements. The covered loss is the efficient proximate cause of the rewiring cost.

2. “It’s Maintenance”

Some carriers characterize outdated wiring as a “maintenance” issue the homeowner should have addressed before the loss. This is wrong. There is no maintenance obligation to proactively replace functional K&T or aluminum wiring in an existing home. The California Electrical Code does not require it. No building department issues violations for wiring that was legal when installed and has not been altered. Characterizing a legally permitted condition as “maintenance neglect” is a misrepresentation of the code.

3. “It’s Betterment”

The carrier argues that replacing K&T or aluminum wiring with modern copper NM-B (Romex) wiring constitutes betterment because the homeowner ends up with “better” wiring than they had before. This argument fails for the same reason it always fails in code-upgrade situations: the homeowner did not request the upgrade. They did not decide to rewire their home. A covered peril damaged their home, the repairs required opening walls, and the building code requires that the exposed wiring be brought to current standards. The “improvement” was forced on them by the combination of the covered loss and the applicable code. They had no choice.

4. Limiting Rewiring to the Damaged Area Only

A carrier may agree to pay for rewiring in the specific rooms that were damaged but refuse to pay for rewiring circuits that pass through the damaged area on their way to undamaged rooms. Electrical circuits do not respect room boundaries. A K&T circuit that serves the damaged bedroom may also serve the adjacent hallway and bathroom. If the circuit must be replaced to comply with code in the damaged area, the entire circuit — including the portions running to other rooms — may need replacement because you cannot splice modern NM-B cable to K&T wiring and pass inspection. Get your electrician’s written assessment of the full scope of rewiring required by the code compliance work in the damaged area.

5. Ignoring the Electrical Entirely

The most common tactic: the carrier’s repair estimate includes drywall, paint, flooring, and other visible repairs but contains no line items for electrical work beyond replacing damaged outlets or switches. The estimate assumes the walls will be opened and closed without any electrical code compliance work. This is not a realistic repair scope for any pre-1950 home with K&T wiring or any 1965–1975 home with aluminum branch circuits where the repairs involve opening walls. The electrical work is not optional — the building inspector will require it.

The Insurance Catch-22: Can’t Insure It, Can’t Replace It

Many insurance carriers will not write new policies — or will non-renew existing policies — on homes with known K&T wiring. This creates a perverse situation. The homeowner cannot get insurance because of the K&T wiring, but they also cannot afford the $15,000 to $40,000 or more it costs to rewire a whole house without a claim to pay for it. And because no regulation requires proactive replacement, they have no code-based reason to force the issue.

When a covered loss finally opens the walls and forces the issue, the carrier that has been collecting premiums — possibly for years on a home it knew had K&T wiring — argues it should not pay for the rewiring. The carrier accepted the risk of insuring a K&T home, collected premiums reflecting that risk, and now wants to avoid paying the foreseeable consequence when a loss occurs. This is worth documenting in your correspondence with the carrier.

Practical Steps to Protect Your Claim

• Get a licensed electrician’s assessment before the walls close. As soon as the repair work exposes wiring, have a licensed electrical contractor (C-10 license) inspect and document what was found. The assessment should identify the wiring type, its condition, the specific code provisions that apply, and the scope of rewiring required to bring the affected areas into compliance. Do not let the carrier’s adjuster close the walls before this assessment is complete.
• Photograph everything before it gets covered up.Photograph the K&T knobs and tubes, the deteriorated insulation, the aluminum connections with visible oxidation or heat damage, and the relationship between the wiring and the damaged area. Once the walls are closed, the evidence is gone.
• Get a detailed written estimate for the electrical work.The electrician’s estimate should break out each component: demolition and access, removal of old wiring, installation of new circuits, panel upgrades (if the existing panel cannot accommodate the new circuits), AFCI and GFCI protection as required by current code, permits, and inspection.
• Include the electrical work in your claim as part of the repair, not as a separate request.Present the repair scope as a single, integrated package that includes demolition, electrical, framing, insulation, drywall, and finishes. The electrical work is not a side project — it is a necessary component of the covered repair.
• Cite the specific code provisions.Reference the California Electrical Code (Title 24, Part 3), NEC §394.12 (prohibition on K&T in insulated spaces), and any local amendments. This puts the carrier on notice that the requirements are mandatory, not discretionary.
• Request the carrier’s denial in writing.If the adjuster verbally tells you the rewiring is “not covered,” demand a written denial citing the specific policy language they rely on. California’s Fair Claims Settlement Practices regulations (10 CCR §2695.7(b)) require written explanations for coverage denials or limitations.

Additional Code Requirements That May Apply

When a covered loss triggers electrical work in an older home, the code compliance requirements extend beyond just the wiring itself. Depending on the scope of the repair, the following may also be required under the current California Electrical Code:

• Arc-Fault Circuit Interrupter (AFCI) protection— NEC §210.12 requires AFCI protection on virtually all 15- and 20-ampere branch circuits in dwelling units. If circuits are being replaced or significantly altered, AFCI breakers or outlets will likely be required.
• Ground-Fault Circuit Interrupter (GFCI) protection— the current code requires GFCI protection in kitchens, bathrooms, garages, outdoors, basements, laundry areas, and other locations. K&T circuits serving these areas have no GFCI protection. When rewired, GFCI protection must be added.
• Electrical panel upgrades— many older homes with K&T wiring have 60-amp or 100-amp electrical panels with obsolete breaker types (Federal Pacific Stab-Lok, Zinsco/Sylvania). If the rewiring adds circuits or the panel cannot accommodate modern AFCI/GFCI breakers, a panel upgrade may be required.
• Grounding and bonding— K&T wiring has no equipment grounding conductor. Modern code requires grounding on all circuits. New circuits replacing K&T must include a grounding conductor, and the grounding electrode system may need upgrading.
• Tamper-resistant receptacles— NEC §406.12 requires tamper-resistant receptacles in all dwelling unit locations. Any new receptacles installed as part of the rewiring must be tamper-resistant.

Each of these requirements adds cost to the repair. Each is mandatory under the current California Electrical Code. None is optional or discretionary. All are covered repair costs or, at minimum, ordinance or law coverage costs triggered by the covered loss.

California-Specific Considerations

California has a disproportionately large number of homes with outdated wiring because of its building history. San Francisco, Oakland, and Berkeley have dense concentrations of pre-1920 homes with K&T wiring — many of which have been modified, extended, or partially updated by previous owners without permits. Los Angeles has enormous numbers of 1920s–1940s bungalows and Craftsman homes with original K&T. The San Fernando Valley, Orange County, and Inland Empire have extensive 1965–1975 tract housing stock with aluminum branch circuits.

After the 2025 Palisades and Eaton fires, thousands of pre-war homes in Pacific Palisades, Altadena, and surrounding areas sustained fire, smoke, and water damage that required opening walls. Many of these homes contained K&T wiring that had been undisturbed for decades. The rebuilding and repair process for these homes necessarily includes electrical code compliance — and the cost is substantial.

California’s efficient proximate cause doctrine also strengthens the policyholder’s position. When the covered peril (fire, water, falling tree) is the event that necessitated the repairs, and the repairs are what triggered the code requirement, the covered peril is the efficient proximate cause of the rewiring cost. The carrier cannot sever the chain of causation by pointing to the pre-existing wiring as a separate “cause” of the cost.

The Bottom Line

Knob-and-tube and aluminum wiring in your home are not your fault, not a maintenance issue, and not a reason for the insurer to reduce your claim. When a covered loss opens your walls and exposes wiring that the California Electrical Code requires to be addressed before the repair can be completed, the rewiring cost is part of the repair. The homeowner did not choose to open the walls. The homeowner did not choose to trigger a code compliance obligation. The covered peril did both.

Do not accept an estimate that pretends the wiring does not exist. Do not accept a betterment deduction for code compliance you did not request. Do not let the walls close before a licensed electrician has documented what is inside them. Get the assessment, get the estimate, include it in your claim from day one, and hold the carrier to its obligation to pay the actual cost of repairing your home — wiring and all.