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# Nine Signs a California Home Needs Rewiring

Knob and tube, cloth insulation, aluminum branch circuits and two-prong outlets. How to tell what is in your walls and which findings are urgent.

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Rewiring | Updated 2026-02-25 | Rupert Electrical Solutions

California's housing stock spans well over a century, and wiring methods that were standard practice in their day are now the reason an insurer won't write a policy. Here is how to read your own house.

## 1. Two-prong outlets

No third slot means no equipment grounding conductor. There is no fault path, so a failure inside an appliance can energize its metal case. Replacing the outlet with a three-prong one and leaving the ground unconnected is worse than doing nothing, because it hides the problem. It is also one of the most common things we find in homes where a previous owner did their own work.

## 2. Knob and tube wiring

Ceramic knobs and tubes in the attic or basement, with individual conductors running separately rather than in a cable. It was competent work for its era, but the rubber insulation is decades past its service life, it has no ground, and it fails badly when buried in modern insulation because it was designed to shed heat into open air.

## 3. Cloth-covered cable

Fabric sheathing over rubber insulation, common through the 1950s. The rubber goes brittle and cracks off the conductor, often right at the box where it flexes most. Once you can see bare copper inside a junction box, no repair exists other than new wire.

## 4. Aluminum branch circuits

Used widely for household branch wiring in the mid-1960s to mid-1970s. Aluminum expands more than copper, creeps under pressure, and oxidizes into a resistive layer, so terminations loosen and run hot over time. Note the distinction: aluminum service entrance and feeder conductors are current, normal practice. It is aluminum in 15 and 20 amp branch circuits that is the concern.

Full replacement is the durable fix, and approved connectors at every termination are a recognized alternative when replacement isn't feasible.

## 5. Breakers that trip with no clear cause

Covered in detail in our piece on tripping breakers, but in the context of old wiring it often means deteriorated insulation is starting to leak or arc inside a wall.

## 6. Warm cover plates, switches or outlets

Heat means resistance. Resistance means a loose or corroded connection. That connection is a heat source inside a wall cavity, and it is the mechanism behind a large share of residential electrical fires. This gets same-day attention, not a note for next spring.

## 7. Not enough outlets, and extension cords everywhere

Not itself a wiring failure, but a symptom of a house wired for a different era of electrical demand. It also creates real hazards: cords under rugs, daisy-chained strips, and a couple of circuits carrying the load of a whole floor.

## 8. A fuse box, or a panel with no room left

Fuse boxes cannot provide AFCI or GFCI protection and invite over-fusing. A panel packed with tandem breakers and double-tapped lugs tells you the house outgrew its service years ago. Either finding usually means the rewire and an electrical panel upgrade happen together.

## 9. Your insurer asked about the wiring

California carriers have grown notably stricter on knob and tube and aluminum branch wiring. Some decline coverage, some load the premium, some require a licensed assessment. Documented replacement is what resolves it, and we provide paperwork specifically for underwriters.

## What a rewire actually involves

New circuits pulled from a new panel to every device, grounded receptacles throughout, dedicated circuits for kitchen, laundry and bathroom, and AFCI protection where required. Wire is fished through existing cavities wherever possible, with small, straight, patch-ready openings where it isn't. Most households stay in the home while it happens, because the work is phased.

Expect one to three weeks for a typical single-family whole house rewiring, driven mostly by square footage, plaster versus drywall, and attic and crawlspace access.

## Don't guess. Get it mapped.

Wiring methods layer over each other. Plenty of California homes have knob and tube in the attic, cloth cable in the walls from a fifties remodel, aluminum in a seventies addition, and modern NM-B where a kitchen got redone. Only some of that needs replacing, and knowing which is the difference between a targeted project and an unnecessary whole-house bill.

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