8 min read · updated 2026-05-10
Whole-house rewire in California: when it's needed and what it costs
Knob-and-tube, aluminum branch wiring, undersized panels — the signs that mean rewire, not patch. Plus 2026 California costs and AFCI/GFCI code triggers.
Three vintages of bad wiring
Knob-and-tube (pre-1950s): individual conductors with porcelain insulators. Works fine when undisturbed; fails when insulation is added on top of it or when modern loads exceed its rating. Insurance carriers in California increasingly decline policies or charge surcharges for knob-and-tube branch circuits.
Aluminum branch wiring (1965–1973): single-strand aluminum used for 15A and 20A circuits. The contact expansion/contraction at devices loosens connections over decades, leading to arcing. The CPSC and ESFI have both flagged the material CPSC — Aluminum branch wiring safety. Two remediation paths: COPALUM crimping at every device (specialized labor, expensive), or full rewire.
Undersized service: pre-1980 California homes often have 60A or 100A panels. Modern households with HVAC, EV charging, induction cooking, and heat pump water heaters routinely exceed 100A continuous load.
When patch is enough vs. when rewire is required
Patch is fine when: a small section of knob-and-tube serves one or two rooms, the rest of the house is modern Romex, the insurance carrier accepts a remediation letter, and no major renovation is planned. Rewire is the right call when: more than 30% of the house is on legacy wiring, the panel is also undersized, insurance is declining, or any major remodel is opening walls anyway.
The economics favor full rewire on any project that's already opening more than 30% of wall surface. Marginal cost of pulling new circuits in open walls is fraction of pulling them through closed walls.
2026 cost ranges in California
Whole-house rewire for a 1,500 sqft single-story home: $18K–$28K. 2,500 sqft two-story: $30K–$45K. Hillside or limited-access homes run 15–25% higher. New 200A panel: $3K–$8K; 200A panel with new service entrance: $5K–$12K. The CSLB licensing search is the first stop for verifying any electrical contractor CSLB — verify electrical contractor license.
Hidden line items: drywall patch and paint after wall opens for wire pulls ($3K–$8K), permit + inspection fees per the LADBS schedule LADBS permit fee schedule, EV charger circuit if added at the same time ($1K–$2K of incremental cost when the panel is already open), and smoke/CO detector replacement to current code if older than 10 years.
Code triggers worth knowing
Current CEC editions require AFCI (arc-fault circuit interrupter) protection on most 120V branch circuits serving habitable space. GFCI (ground-fault) is required in kitchens, bathrooms, laundry, garage, exterior, and within 6 ft of any sink. Tamper-resistant receptacles are required throughout.
A rewire is the moment to bring every circuit current. Half-measures (rewiring the kitchen but leaving the rest on old branch circuits) often fail inspection on the new work because the existing panel can't accept the required AFCI breakers without an upgrade.
Frequently asked
- How disruptive is a whole-house rewire?
- Significant. Walls get opened in patterns, power is intermittent, and most homeowners choose to be out for at least the rough-in phase (1–2 weeks). 'Less invasive' attic-and-crawlspace methods exist but only work on certain framing types.
- Will my insurance carrier require a rewire?
- California carriers increasingly require remediation of knob-and-tube and aluminum branch wiring at policy renewal. Get the rewrite decision in writing from your underwriter before assuming.
- Can I do it in phases?
- Yes — many rewires happen room-by-room over a year or two during other remodel work. The phased approach costs 20–35% more in total but spreads the disruption.
Sources we cited
- 1.CPSC — Aluminum branch wiring safety — U.S. Consumer Product Safety Commission
- 2.CSLB — verify electrical contractor license — CSLB
- 3.LADBS permit fee schedule — LADBS
Referenced resources
Permit portals, fee bands, and code notes that back up the jurisdictions named in this article.
Related areas
Neighborhood guides that pair with this article — local code, lot patterns, and what we've actually built nearby.