Knob and tube home buyer and insurer checklist

Before you remove the inspection contingency

A general home inspection notes what it can see. It does not always tell active circuits from disconnected ones, so ask for the records behind "knob and tube noted".

• Ask the seller for every electrical permit on the building and whether each one was finaled. In San Francisco these are DBI permits; in the East Bay, the city building department.
• Read the seller disclosures for wiring. Since January 1, 2026, California sellers must give buyers a statement advising an inspection of the electrical system.
• Ask whether any rooms were rewired, when, and whether the old runs were disconnected or left live.
• Ask whether the attic or walls were insulated, and whether an electrician surveyed the wiring first.
• Call your insurer and lender before the contingency ends and ask what they will need about the wiring.
• If the scope is uncertain, get every circuit tested and a written scope and price before you negotiate a credit or repair.

Questions for the insurer

Each carrier sets its own rules, and homeowners report wide differences between them. Get the answers in writing, with a name and a date.

• Does the application ask about knob and tube? What exactly does it ask?
• Does it matter whether the knob and tube is active (carrying power) or abandoned (disconnected)?
• What proof do you accept: a letter from a licensed electrician, a finaled permit, a written circuit record, photos of the panel?
• If replacement is required, by when? Does replacing only the live circuits satisfy it?
• Does a fuse panel, or the age of the panel, change the answer?
• Will the policy include an on-site inspection, and what will it look at?
• If you do not renew, how will I be told? California law requires written notice at least 75 days before a non-renewal, with the reason.

California Department of Insurance residential guide

Questions for the electrician

These turn a note in a report into a scope you can price, compare and hand to an insurer.

• Is any knob and tube still live, and on which circuits? Will you test every circuit?
• Which runs are abandoned, and are they disconnected at both ends?
• Is any knob and tube under attic or wall insulation?
• Where is knob and tube spliced into newer wiring?
• Can the panel take the new circuits, or does the panel or service need an upgrade as a separate line?
• Which three-prong outlets are on circuits with no ground wire?
• Will every live run be replaced? If not, what stays, and where does new wiring meet old?
• Who pulls the permit, and which inspections will the city do before the walls close?
• How many openings in plaster walls and ceilings, where, and who closes them? Is patching a line in the quote?
• For a building built before 1979, how will openings follow lead-safe practice?
• What is your California contractor license number? Electrical contractors hold the C-10 classification, and any license can be checked with the Contractors State License Board.

Check a contractor license with the CSLB

Records to collect

Keep these together. They are what an insurer, a lender or the next buyer asks for.

• The electrical permit and its final inspection sign-off.
• A written circuit record: which circuits were replaced, which knob and tube runs were found live, and which were left in place disconnected.
• A photo of the panel with its labeled circuit directory, taken when the work is finished.
• The written scope and price, listing each opening and who closes it.
• If knob and tube stays under insulation: the licensed electrical contractor's survey and certification the California Electrical Code requires, filed with the building department. Berkeley uses its own Form 146 for this.
• Letters or emails from the insurer stating what it requires.
• If you apply for a BayREN EASE Home rebate: the licensed electrician's invoice or certification of knob and tube inactivity the program asks for.

Local differences to check

The state code is the same everywhere; the permit office, the utility and some local rules are not.

• San Francisco: DBI requires a separate electrical permit for each dwelling unit in a building of three or more units, and an inspection before wiring is covered.
• Berkeley: insulating an attic with knob and tube needs the signed Form 146 posted in the attic before inspection. Sellers of houses and duplexes also face Berkeley's building energy rules at sale.
• Oakland: a service change needs a PG&E clearance letter before the city releases the meter.
• Alameda: power comes from Alameda Municipal Power, not PG&E, so BayREN EASE Home rebates do not apply, and the city does not allow knob and tube to be extended.
• Piedmont, Albany, El Cerrito and Richmond: confirm the permit process and any local electrical amendments for the address.

Partial-work boundary record

When only part of a building is rewired, write down where the new wiring stops. Fill this in with the electrician before the walls close.

• Address and unit
• Date of work
• Contractor and license number
• Permit number
• Rooms and circuits replaced
• Live knob and tube left in service, and where
• Abandoned runs left in walls or ceilings, and how they were disconnected
• Where new wiring connects to old (junction box locations)
• Attic and walls: insulated or not, and over what wiring
• Notes

Related reading

Buying a house with knob and tube, knob and tube and insurance in California, an electrical inspection for insurance, the knob and tube risk assessment and the cost estimator.