Knob and Tube Wiring Replacement in San Jose and Santa Clara County. Ungrounded, Insulation-Blocked, Flagged by Insurers.

No, knob and tube wiring is not illegal, but it is prohibited in new construction and heavily restricted under current California code. Existing K&T is permitted to remain in place as long as it is not actively unsafe, modified, or covered by insulation without proper certification. The practical reality in 2026 is that it has become very difficult to insure a home with active K&T. The code does permit extensions of an existing K&T installation, but our team will not put new work on ungrounded wiring, so any new circuit we run uses modern grounded cable. K&T cannot be buried under insulation without an electrical contractor licensed by the State of California certifying its condition in writing to the local building department. And it cannot remain in any remodeled area that requires a permit.

Not freely. It requires a formal certification process and carries real risk. Knob and tube was designed to dissipate heat into open air. Covering it with insulation traps that heat against the conductors and can cause a fire. Under the California Electrical Code, insulation may be installed over existing K&T only if an electrical contractor licensed by the State of California inspects the wiring and certifies in writing that it is in good condition with no deterioration, no improper overcurrent protection, and no improper splices, that certification is filed with the local building department, and the insulation contractor posts a caution notice, printed in both English and Spanish, at all accessible areas where insulation was installed around the wiring. The insulation itself has to be noncombustible as defined in the California Building Code and cannot have any electrically conductive material as part of it or supporting it. If the inspection finds any deterioration, insulation cannot go in until repairs or replacement are completed. Most insurance carriers will not accept a certification as a substitute for full replacement.

Cali Rollin Electric pricing for knob and tube replacement in Santa Clara County: partial replacement covering the kitchen, bathrooms, and visible runs runs $8,000 to $14,000. Whole-house K&T replacement runs $15,000 to $25,000 or more depending on home size. Attic and crawl space K&T removal for non-active wiring runs $2,000 to $5,000. Adding a panel upgrade at the same time adds $1,500 to $3,000. Permits vary by city and typically add $500 to $1,000 depending on jurisdiction. All pricing is provided in a written quote after a full circuit assessment.

It is a growing risk across the Bay Area. New policy applications on homes with active K&T are now declined by most major carriers, and existing policyholders are receiving non-renewal notices that give 30 to 90 days to rewire or lose coverage. Carriers treat active knob and tube as an unacceptable underwriting risk regardless of whether anything has ever gone wrong in the home. Real estate transactions stall for the same reason, because a lender will not fund a mortgage on a home that cannot be insured. The remedy carriers reliably accept is replacement of the live circuits, documented with a closed permit.

Technically only active, meaning energized, K&T circuits must be addressed. Inactive, disconnected wiring that carries no current poses no fire risk and can legally remain in the walls. In practice, if your goal is insurance compliance, most carriers want written confirmation that no live K&T remains anywhere in the home, and a partial rewire that leaves some energized K&T in service will not satisfy them. During the free assessment, our team maps all active K&T circuits with a circuit tracer, separates what is truly live from what was abandoned years ago, and gives you a clear scope. Homeowners are often surprised to find that parts of the house were already rewired at some point, which reduces both scope and cost.

On-site electrical work takes 3 to 15 working days depending on home size and access. The full project timeline from first call to final inspection runs 4 to 10 weeks for most Santa Clara County single-family homes once permitting and inspections are factored in. Permit approval typically takes 5 to 15 business days depending on the jurisdiction. Plaster walls in older homes require slower, more careful wire fishing. Two city inspections are required, a rough-in inspection before walls are closed and a final inspection after completion. Drywall patching and painting by a separate contractor follows electrical sign-off. You can stay in the home during the rewire in most cases, because our crew works room by room to keep the rest of the house functional.

The clearest sign is visual. In an unfinished attic or basement, look for single conductors, not a cable bundle, strung along the framing and supported by white porcelain knobs, passing through joists inside ceramic tubes. The conductors are covered in rubber and cloth rather than modern plastic, and the hot and neutral are run separately with air between them. Other indicators: two-prong ungrounded receptacles throughout the home, a fuse panel rather than breakers, and a build date before about 1950. None of those is proof on its own, because many homes have been partly rewired, so the only reliable answer comes from tracing circuits back to the panel. That is what the free assessment does.

Some access is unavoidable, and the goal is to keep it minimal and in predictable places. Most new cable is fished through attics, crawl spaces, and closets, with small openings cut at switch, outlet, and junction locations and at the top and bottom of wall bays where fishing is blocked by fire blocking. Plaster and lath takes more care than drywall and is the reason older homes take longer. We walk the planned access points with you before work begins, so nothing gets cut that you have not seen on the plan. Drywall or plaster patching, texture, and paint are handled by a separate finish contractor after the final electrical inspection, and we tell you that up front rather than at the end.

Not on its own, but the two travel together often enough to be worth checking. A fuse box was the standard service equipment in the same era knob and tube was the standard wiring method, so a pre-1950 home that never had its service replaced frequently still has original circuits live in the attic and the wall cavities. The reverse happens just as often: the fuse box gets swapped for a breaker panel while the wiring behind it is left exactly as it was, which is why a modern panel proves nothing about what is in the walls. A fuse box is a strong reason to look, not an answer by itself. Our team traces the circuits back from the panel during the free assessment so you get a finding rather than an inference, and if the fuse box is still in service we run a load calculation at the same visit, because a rewire adds circuits an original 60-amp or 100-amp fuse box has no room for.

It depends entirely on whether it is still energized. Old knob and tube wiring that was disconnected years ago carries no current, poses no fire risk, and can legally stay where it is. Energized old knob and tube wiring is a different matter: the rubber and cloth covering on those conductors is 80 or more years old and has spent decades getting brittle, there is no equipment ground behind any receptacle it feeds, and later remodels routinely spliced modern cable onto it inside wall cavities with no junction box. For most Santa Clara County homes the honest answer is that the live circuits need to go and the abandoned runs can stay, unless they sit in the way of an attic insulation job. The assessment separates the two before anything is quoted.

Not always, but the two often travel together. Homes still on original K&T frequently still have the original service as well, commonly a 60-amp or 100-amp fuse panel with no room for the additional circuits a modern rewire adds. If the existing panel is sound, has capacity, and has open positions, the rewire can land on it. If it is a fuse panel, an obsolete or hazardous brand, or already full, replacing it during the rewire is far cheaper than doing it as a separate job later, and it adds roughly $1,500 to $3,000 to the project. Our team runs a load calculation during the same assessment so the answer is a number, not an opinion.