LA Knob and Tube: knob and tube replacement in Los Angeles, CA
Most of it sits in the attics and crawlspaces of houses built before 1940. The replacement is planned circuit by circuit, through those spaces first, so plaster walls are opened only where a route has no other way in.
19.1%of homes in the City of LA were built before 1940, by the Census Bureau's count
ExpressLADBS issues nearly every house rewire permit as an express permit, with no plan check
394.12California's rule on insulating over knob and tube, explained in plain terms
What brought you here
Most calls about knob and tube start with one of four findings.
The inspection found it
A buyer's report in escrow names knob and tube and recommends an electrician's evaluation before closing.
The insurer asked
A carrier wants an electrician's letter, a replacement plan or proof that the old circuits are out of service.
Attic insulation stalled
The insulation contractor stopped at the porcelain knobs, because California sets conditions before insulation can cover them.
A remodel opened a wall
Cloth-covered wires turned up behind the plaster, and nobody knows whether they still carry power.
Knob and tube services
LA Knob and Tube replaces knob and tube wiring across the City of Los Angeles, Pasadena, Glendale and South Pasadena. The work is carried out by licensed and insured electrical contractors, and every service starts from the same map of which circuits are still live.
Partial replacement
Replace the live circuits that matter now and document exactly where the old system stops.
Inspection
Find out which circuits are still live, what condition the reachable wiring is in, and what cannot be seen.
Removal
Disconnect old runs for good, prove they are dead, and pull out the ones that are worth removing.
Plaster-wall rewiring
Route new circuits through the attic and crawlspace, keep openings small and planned, and agree the patching before work starts.
Attic insulation
Certify the old wiring under California's exception, or replace the attic circuits first and insulate without conditions.
Whole-house rewiring
Replace every old branch circuit, knob and tube or not, and add the circuits and protection a modern house needs.
Panel upgrade
Replace a fuse box or undersized panel with capacity for the new circuits, coordinated with the utility and the rewire.
What is knob and tube wiring, and what should an LA homeowner do about it?
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.
Why the work is planned this way
Attic and crawlspace first
Where a pre-war house sits on a raised wood floor with an attic above, new cable can usually travel through open space before anyone cuts plaster. Openings go where a route has to cross a wall or ceiling.
The right permit office
Rewiring in the City of LA is permitted and inspected by LADBS. Pasadena, Glendale and South Pasadena each have their own building departments, and Pasadena and Glendale run their own electric utilities.
Electrical and patching priced apart
The quote lists which openings are made, who closes them and whether paint is included, so the electrical price and the plaster price can be compared separately.
Partial work is documented
When some knob and tube stays, the quote names the circuits that remain, so an insurer or buyer is never told the house is clear when it is not.
How a job runs
First call
What you have seen, the age of the house, and any inspection, insurer or escrow deadline.
Walk-through and circuit map
Which runs are live, which are dead, the panel, attic and crawlspace access, and where openings would go.
Permit and rewire
Circuits are replaced in sequence, so most of the house keeps power on most days.
Inspection and patching
The city inspection, a labeled panel, and the openings closed as the quote describes.
Found knob and tube in an inspection report? Start with a map of what is still live.
What knob and tube replacement costs in LA
These are ranges for planning, not quotes. Circuit count, attic and crawlspace access, and how much plaster has to be opened move a house within them.
| Work | Range | What the range covers |
|---|---|---|
| Whole-house knob and tube replacement | $12,000 to $35,000national budgeting range | Replacing the branch circuits in a typical house. Panel work and plaster restoration vary and are priced separately. |
| Replacement priced by floor area | $10 to $20 per sq fttypical LA-area range | Whole-house rewiring of the finished living area, before panel and patching costs. |
| Panel upgrade, 100 to 200 amps | $2,500 to $5,500typical LA-area range | A new panel in the same location, with no meter, mast or utility-side work. |
| New or replaced outlet | $150 to $350 eachtypical LA-area range | One receptacle on an existing circuit. Inside a whole-house rewire, outlets are part of the job price. |
Repair, partial or full replacement
The right scope depends on how much of the old system is still live, what the insurer or buyer needs, and what access the house gives.
| Targeted repair | Partial replacement | Full replacement | |
|---|---|---|---|
| When it fits | One damaged splice or device on a circuit that is otherwise in sound condition | A few live circuits left after earlier remodels | Most lights and outlets still on original runs |
| What it leaves | The rest of the old system in service | A documented boundary, with some old wiring still live | No live knob and tube |
| Insurance | Rarely settles an underwriting question | Some carriers accept it and some do not, so ask before scoping | The scope most likely to satisfy an insurer |
| Wall openings | Usually none | Fewer, in the rooms being changed | At boxes and where routes cross framing |
Where the work happens
Each city has its own permit office, and Pasadena and Glendale have their own electric utilities. Permit counts are single-family rewire permits in LADBS open data, January 2020 to October 2026.
| Area | Permit office | Electric utility | House rewire permits |
|---|---|---|---|
| Eagle Rock | LADBS | LADWP | 95 in 90041, January 2020 to October 2026 |
| Glendale | City of Glendale Building & Safety | Glendale Water & Power | n/a |
| Hancock Park & Windsor Square | LADBS | LADWP | 64 in 90004, 9 in 90020 and 17 in 90005, January 2020 to October 2026 |
| Highland Park & Mount Washington | LADBS | LADWP | 169 in 90042 and 119 in 90065, January 2020 to October 2026 |
| Leimert Park & Hyde Park | LADBS | LADWP | 126 in 90043, 96 in 90008, 106 in 90047 and 63 in 90062, January 2020 to October 2026 |
| Mid-City, Miracle Mile & Carthay | LADBS | LADWP | 113 in 90019, 36 in 90036 and 32 in 90035, January 2020 to October 2026 |
| Pasadena | City of Pasadena Building & Safety | Pasadena Water & Power | n/a |
| Silver Lake & Echo Park | LADBS | LADWP | 132 in 90026 and 91 in 90039, January 2020 to October 2026 |
| West Adams & Jefferson Park | LADBS | LADWP | 85 in 90018, 112 in 90016 and 36 in 90007, January 2020 to October 2026 |
| Lincoln Heights & El Sereno | LADBS | LADWP | 59 in 90031, 95 in 90032 and 32 in 90033, January 2020 to October 2026 |
| Los Feliz & Atwater Village | LADBS | LADWP | 83 in 90027 and 91 in 90039, January 2020 to October 2026 |
| South Pasadena | City of South Pasadena Building Division | Southern California Edison | n/a |
Knob and tube questions
Is knob and tube wiring dangerous?
Intact, unaltered knob and tube is not dangerous by default. The risk comes from what age and later work did to it: brittle insulation, splices added without boxes, fuses or breakers larger than the wire can carry, and insulation packed around conductors that were designed to shed heat into open air.
Is knob and tube legal in California?
Existing knob and tube is not banned in California. The California Electrical Code does not allow it in hollow spaces where insulation surrounds the conductors, unless a California-licensed electrical contractor surveys and certifies the wiring first. New circuits are run with modern cable.
Can I get home insurance with knob and tube?
It depends on the carrier. Some decline houses with active knob and tube at the application, and others ask for an electrician's evaluation or a replacement plan. Ask your carrier or broker what it needs in writing before the work is scoped, because that answer often decides between partial and full replacement.
Will my plaster walls be opened?
Some openings are normal, usually at outlet and switch boxes and where a route has to cross framing. Using the attic and crawlspace keeps the number down. The quote should list the openings and say who patches them.
Do I have to replace all of it?
No rule requires an existing house to be fully rewired. A buyer, an insurer or an attic insulation project usually decides how much has to go, and partial replacement is common when earlier remodels already replaced some circuits.
Does a new panel remove knob and tube?
No. A panel upgrade replaces the breakers and the service equipment, while the old branch wiring stays in the walls and ceilings until it is rewired. The two jobs are often done together, but they are separate scopes.
Is a three-prong outlet proof of a ground?
No. A three-prong outlet on a knob and tube circuit has no ground wire behind it unless one was run later. Only testing at the outlet shows whether a grounding path exists.
How long does a rewire take?
A partial job can take a few days, and a whole house takes longer, depending on the number of circuits and how open the attic and crawlspace are. Patching and the city inspection add time after the wiring is done.
Do I need a permit in Los Angeles?
Yes. Rewiring needs an electrical permit and inspection. In the City of LA that is LADBS, which issues nearly all house rewire permits as express permits without plan check. Pasadena, Glendale and South Pasadena permit through their own building departments.
What does the first visit look at?
The panel, which circuits are still knob and tube and whether they are live, the attic and crawlspace, the wall and ceiling finishes, and where new cable could run with the fewest openings.
Get an estimate for your house
Tell us what you have found and where the house is. A call is the quickest way to start.
Call (323) 831-7471LA Knob and Tube5317 N Figueroa St, Los Angeles, CA 90042
office@laknobandtube.com