# How does knob and tube affect home insurance in California?

> Knob and tube insurance in California varies by carrier. Learn what to ask in writing and what an electrician's letter covers, then plan the work around it.

URL: https://laknobandtube.com/guide/knob-and-tube-insurance-california/

What carriers tend to ask, how to get their answer in writing, what an electrician's letter can and cannot say, and where the FAIR Plan fits.

Last Updated: October 25, 2026

Knob and tube insurance in California depends on the carrier. Some insurers decline a house with active knob and tube, some ask for an electrician’s evaluation, and some accept partial replacement with documentation. Rules differ and change over time, so get your carrier’s requirement in writing before the scope of any work is set.

[LA Knob and Tube](https://laknobandtube.com/) replaces knob and tube wiring in Los Angeles, Pasadena, Glendale and South Pasadena, and the insurer’s answer can decide between a partial job and a whole-house rewire. This guide covers what carriers tend to ask, how to get a usable answer from yours, and the paperwork that helps. It does not predict what any carrier will do, because nobody outside the carrier can.

Key takeaways

- Carriers set their own knob and tube rules, and they change
- Ask for the requirement in writing before choosing partial or full replacement
- The usual question is whether any knob and tube is still energized
- An electrician's letter describes the wiring; it does not guarantee acceptance
- A California non-renewal needs at least 75 days' written notice with reasons

## Why carriers care about old wiring

An insurer is pricing the chance of a claim, and old wiring is one of several building features underwriters look at, alongside the roof, plumbing and foundation. For knob and tube, the concern is the same set of conditions described in the [dangerous or not guide](https://laknobandtube.com/guide/is-knob-and-tube-wiring-dangerous/): brittle insulation, later splices, oversized fuses, overloading and insulation packed around conductors. The difficulty for an underwriter is that most of those are hidden, so some carriers use the presence of active knob and tube as a simple screen rather than trying to judge condition.

Bay Area news reporting from 2023 to 2025 described brokers saying that listing knob and tube on an application led to declines, and owners of older houses being non-renewed for age-related underwriting reasons. Those reports name no Los Angeles rule and no state policy on knob and tube. They describe a pattern in how some carriers underwrite, and that pattern is why the first step is to ask yours.

## Where the market stands

California’s wider insurance market has tightened, and that is the setting for any conversation about older wiring. The California FAIR Plan, the state’s insurer of last resort, had 236,515 residential policies in force in September 2021 and 621,234 in September 2025, according to the FAIR Plan Association. By June 2026 its total policies in force had reached 696,562. The growth shows up in older LA neighborhoods too: in [Highland Park’s](https://laknobandtube.com/service-areas/highland-park-mount-washington/) 90042, FAIR Plan residential policies rose from 810 to 1,090 over the same four years, and in [West Adams’s](https://laknobandtube.com/service-areas/west-adams-jefferson-park/) 90018 from 977 to 1,086.

Those numbers reflect wildfire risk and carriers pulling back across the state. They are not a measure of knob and tube. They matter because an owner who is declined by one carrier is shopping in a market with fewer options, which makes a clear answer about the wiring more valuable.

## What to ask your carrier, in writing

A phone answer from an agent is a starting point. A written answer from the carrier or broker is something you can plan around. Useful questions:

1. Does active knob and tube make the house ineligible, or does it depend on condition or extent?
2. Is partial replacement acceptable? If so, which circuits or rooms must be replaced, for example kitchen, bathrooms, attic runs or everything on the first floor?
3. Does disconnected knob and tube left in the walls count against the house?
4. What evidence do you need: an electrician’s letter, a permit with final inspection, photos, a circuit list?
5. Who has to sign the letter? A California-licensed electrical contractor, a home inspector, anyone?
6. Is there a deadline, such as replacement within a set number of days after the policy is bound?
7. Does the answer differ for a two- to four-unit building?

Among the requests homeowners and real estate agents report hearing from carriers are a statement of whether any knob and tube is still energized and a commitment to finish replacement by a set date. If you are buying, ask before your contingency period ends. The [buying guide](https://laknobandtube.com/guide/buying-a-house-with-knob-and-tube/) covers that timing, and the [selling guide](https://laknobandtube.com/guide/selling-a-house-with-knob-and-tube/) covers the same question from a seller’s side.

## What an electrician’s letter can say

An electrician’s letter is a description of the wiring by someone qualified to describe it. It can state which circuits are still knob and tube, whether they are energized, which rooms they serve, how they are protected at the panel, what condition the accessible runs are in, what has been replaced and under which permit, and which old runs were disconnected at both ends.

It cannot honestly say the wiring inside closed walls is in good condition, because nobody has seen it. And it cannot promise acceptance, because only the carrier decides that. A letter is most useful when it answers the carrier’s written questions point by point, in the carrier’s own terms. The guide to [active and abandoned knob and tube](https://laknobandtube.com/guide/active-vs-abandoned-knob-and-tube/) explains how “live” and “dead” are confirmed, which is usually the heart of the letter.

## Partial or full replacement for insurance

If the carrier accepts partial work, a [partial replacement](https://laknobandtube.com/partial-knob-and-tube-replacement/) aimed at the circuits it names can be enough, and it costs less than rewiring everything. The risk is replacing the wrong circuits: a job that leaves the attic runs live when the carrier cared about the attic does not solve the problem it was paid to solve. That is why the written requirement comes before the scope.

If the carrier wants no active knob and tube at all, or the answer is unclear, [whole-house rewiring](https://laknobandtube.com/whole-house-rewiring/) answers the question most completely. Either way, the job documents the result: a permit with final inspection, a labeled panel and, for partial jobs, a written list of the circuits that remain. The [LA cost guide](https://laknobandtube.com/guide/knob-and-tube-replacement-cost-los-angeles/) covers what each path tends to cost.

## If you receive a non-renewal notice

California Insurance Code section 678 requires an insurer that will not renew a residential policy to send written notice at least 75 days before expiration, with the reasons, and to refer you to the Department of Insurance’s California Home Insurance Finder. If the reason given is the wiring, use those 75 days. Ask the carrier, in writing, whether completed replacement would change its decision. Book a [knob and tube inspection](https://laknobandtube.com/knob-and-tube-inspection/) so you know what is actually live. And talk to a broker who can approach several carriers, so you are not relying on one answer.

## Answering application questions

Answer every question about wiring accurately. If knob and tube has been fully disconnected, the accurate answer usually includes that fact and the paperwork to back it up. If some remains, say how much and where. Real estate agents report that coverage obtained on an inaccurate answer can be cancelled later, which leaves an owner in a worse position than a decline at the start.

The most useful thing you can bring to a broker is a clear description of the wiring. Once you have your carrier’s written requirement, call and we can plan the work around it.

## Questions about this guide

### How much notice must a California insurer give before non-renewing a home policy?

Under Insurance Code section 678, an insurer that will not renew a residential policy must send written notice at least 75 days before the policy expires, with the reasons. The notice must also refer you to the Department of Insurance's California Home Insurance Finder. That window is the time to get an electrician's evaluation and talk to a broker.

### What should an electrician's knob and tube letter for an insurer say?

Whatever the carrier asks for, in its own words. Usually that means whether any knob and tube is still energized, which circuits and rooms it serves, its condition and protection, what was replaced and under which permit, and what was disconnected. Get the carrier's requirement in writing first, then ask the electrician to answer it point by point.

### Should I tell my insurer about knob and tube that has been disconnected?

Answer every application question accurately. If the old wiring is disconnected, say so and be ready to show documentation, such as an electrician's letter and the permit for the replacement work. A vague or inaccurate answer can cause problems later, at renewal or after a claim.

## More guides

- Learn [What is knob and tube wiring, and what should an LA homeowner do about it?](https://laknobandtube.com/guide/knob-and-tube-wiring/)How the system works, why it was a sound design in its day, what goes wrong with it now, and how Los Angeles owners decide what to do.
- Decision Guide [Is knob and tube still active in your house, or abandoned?](https://laknobandtube.com/guide/active-vs-abandoned-knob-and-tube/)How live, dead and mixed wiring is told apart, why the answer is rarely visible, and what it changes for an insurer, an insulation job and removal.
- Decision Guide [What should you know before buying a house with knob and tube?](https://laknobandtube.com/guide/buying-a-house-with-knob-and-tube/)How to fit an electrical evaluation, an insurance answer and a negotiation into the time escrow gives you.
- Decision Guide [What should you do when selling a house with knob and tube in California?](https://laknobandtube.com/guide/selling-a-house-with-knob-and-tube/)The disclosures every California seller gives, the choice between rewiring first and pricing it in, and the paperwork that keeps a partial job from becoming a surprise.
- Cost Guide [How much does knob and tube replacement cost in Los Angeles?](https://laknobandtube.com/guide/knob-and-tube-replacement-cost-los-angeles/)The ranges, what moves a house within them, and the parts of the price that come from public figures.