Rewiring an older California home is not the same job as adding an outlet. The right electrician has to identify what is already in the walls, from 1920s knob-and-tube to 1970s aluminum branch circuits, plan a route through plaster and stucco, pull permits and leave the house safer, not just newer. This guide covers who to call, what each wiring era means, which repairs federal safety experts accept, and what a full rewire costs.
Best Electricians for Rewiring Older California Homes: Where to Start
Look for contractors that list rewiring as a core service rather than an add-on, and that can show you photos of past jobs in homes like yours. Two California companies that list whole-home rewiring and aluminum wiring replacement among their main services:
- High Voltage Electrical reports more than 20 years in business across Los Angeles, Orange, Ventura and Santa Barbara counties. It lists house rewiring and aluminum wire replacement as standard services, and its website includes a case study of a home upgraded from knob-and-tube wiring.
- Electrical Land offers whole-home rewiring, wiring repair and aluminum wiring replacement in dozens of California cities, from Los Angeles and Long Beach to Santa Barbara, San Jose and San Francisco, with pricing approved before work begins.
Whichever company you call, confirm its C-10 Electrical license on the Contractors State License Board (CSLB) website and ask how many full rewires it completed in the past year.
What Kind of Wiring Does Your Older Home Have?
| Wiring type | When it was installed | Main concern | Typical fix |
|---|---|---|---|
| Knob-and-tube | Common from the 1880s; largely abandoned in the U.S. by the 1930s and 1940s | No ground wire; brittle insulation; overheating if buried in insulation or overfused | Replacement with modern grounded cable |
| Aluminum branch circuit wiring | About 1965 to the mid-1970s | Connections at outlets and switches can overheat | Full rewire, or CPSC-recognized COPALUM or AlumiConn repairs |
| Ungrounded two-wire circuits | Common in older homes before grounding became standard | Two-prong outlets; no equipment ground for modern devices | New grounded circuits, or code-allowed GFCI protection as an interim step |
You can often identify aluminum wiring by “AL” or “Aluminum” printed on the cable jacket in an unfinished basement, attic or at the panel. Copper-clad aluminum is a different product and is not covered by the CPSC repair recommendations.
Warning Signs Your Home Needs Rewiring
- Outlet or switch cover plates that feel warm
- Flickering lights or circuits that stop working intermittently
- A burning-plastic smell near outlets or switches
- Two-prong outlets throughout the house
- A fuse box, or breakers that trip under normal use
- An insurance company or home inspector flagging knob-and-tube or aluminum wiring
The U.S. Consumer Product Safety Commission (CPSC) warns that failing aluminum connections can also fail without any prior signs, which is why an inspection by a qualified electrician matters even in a home that seems fine.
Rewire or Repair? What the CPSC Recommends for Aluminum Wiring
In its Publication 516, the CPSC reports that homes built before 1972 with aluminum branch wiring are 55 times more likely to have one or more outlet connections reach fire hazard conditions than homes wired with copper. It recognizes three permanent remedies:
- Complete replacement with copper wiring, the most effective option, though often the most disruptive.
- COPALUM crimp connectors, installed by manufacturer-trained electricians to pigtail each aluminum wire to a short copper lead.
- AlumiConn connectors, an acceptable alternative when COPALUM is not available.
The CPSC does not consider twist-on wire connectors or CO/ALR devices to be complete permanent repairs.
Knob-and-Tube Wiring and Insulation: The California Rule
Many homeowners rewire because they want to insulate. The California Electrical Code (Article 394.12) prohibits concealed knob-and-tube wiring in wall, ceiling or attic cavities insulated with loose, rolled or foamed-in-place insulation that surrounds the conductors. California does allow a narrow exception: as Menlo Park’s building division explains, a California-licensed electrical contractor must first inspect the wiring and certify it is in good condition, caution notices must be posted, and the insulation must be noncombustible. Requirements vary by city, so ask your building department before insulating.
How Much Does Rewiring an Older California Home Cost?
| Scope | Typical cost |
|---|---|
| Whole-home rewiring, per square foot | $6 to 10 per sq. ft. |
| 1,000-square-foot home | $6,000 to 10,000 |
| Electrical panel upgrade (often done alongside) | $1,300 to 3,000 |
Source: This Old House, “How Much Does an Electrician Cost?” (updated June 2026). National figures; California quotes often run higher.
Plaster walls, crawl-space access, two-story layouts and patching all move the price. Ask for a quote that separates electrical work from drywall or plaster repair, so you can compare bids fairly.
Questions to Ask Before You Hire a Rewiring Electrician
- How many whole-home rewires have you done in houses built before 1950?
- Will you pull the permit and schedule all inspections?
- Can the family stay in the home during the work, and which rooms lose power each day?
- Who patches the walls, and is that included in the price?
- Will you upgrade the panel or service at the same time, and is it needed?
- Are your crew members DIR-certified electricians or registered trainees under supervision?
Frequently Asked Questions
Who are the best electricians for rewiring older California homes?
Look for licensed C-10 contractors that list whole-home rewiring as a core service and can show past work in homes of the same era. High Voltage Electrical and Electrical Land both list house rewiring and aluminum wiring replacement among their main services in California. Always verify the license on the CSLB website.
How much does it cost to rewire a house in California?
National data from This Old House put whole-home rewiring at $6 to $10 per square foot, or about $6,000 to $10,000 for a 1,000-square-foot home. California projects often cost more because of higher labor rates, plaster walls and permit requirements.
Is knob-and-tube wiring illegal in California?
Existing knob-and-tube wiring is not automatically illegal, but new knob-and-tube installations are not permitted without special permission, and the California Electrical Code prohibits burying it in most types of insulation. Insurers and buyers often ask for replacement or an electrician’s evaluation.
Is aluminum wiring dangerous?
Aluminum branch wiring installed from about 1965 to the mid-1970s carries a higher fire risk at connections. The CPSC found pre-1972 aluminum-wired homes 55 times more likely to have outlet connections reach fire hazard conditions than copper-wired homes. Full replacement or COPALUM or AlumiConn repairs are the accepted fixes.
Do I need a permit to rewire my house in California?
Yes. Rewiring requires an electrical permit and inspections, and because permitted work falls outside California’s $1,000 minor work exemption, it must be done by a licensed electrical contractor.
Next Step
Before calling contractors, note your home’s build year, check the cable jacket in the attic or at the panel for “AL” markings, and count how many two-prong outlets you have. That information lets an electrician give you a realistic first estimate.
