TL;DR

  • Knob-and-tube (pre-1950 homes) and aluminum branch wiring (1965-1973 homes) are both increasingly uninsurable in San Diego County.
  • Knob-and-tube’s biggest risk: blown-in attic insulation covering the wires causes overheating. Aluminum wiring fails at connection points where oxidation and thermal expansion create heat.
  • COPALUM crimp remediation for aluminum wiring costs $4,500-$9,500 and satisfies most insurance carriers without a full rewire.
  • Whole-home rewiring costs $12,000-$28,000+ but is done in phases — most homeowners stay in the house throughout the project.

Two old electrical wiring types still show up in San Diego County homes regularly: knob-and-tube (homes built before about 1950) and aluminum branch circuit wiring (homes built between roughly 1965 and 1973). Both have well-documented safety issues. Both are increasingly difficult to insure.

If you have either, here’s what’s actually going on, what your insurance company is going to ask, and what remediation involves.

Knob-and-tube wiring

What it is

Knob-and-tube was the standard residential wiring method in the United States from roughly 1880 to 1940. It uses:

  • Porcelain “knobs” screwed into framing to hold conductors away from wood
  • Ceramic “tubes” that conductors pass through when crossing framing members
  • Two separate insulated conductors — one hot, one neutral — running through the structure with air space between them
  • Cloth or rubber insulation on the conductors themselves (not modern PVC)

Where you’ll find it in San Diego

Older homes in:

  • North Park, South Park, Mission Hills, Hillcrest (1900s–1930s craftsman and bungalow neighborhoods)
  • Coronado (older sections from the 1900s–1920s)
  • Encinitas, Leucadia, Cardiff (older beach bungalows)
  • The original parts of Escondido, Vista, and Oceanside (pre-WWII town centers)

Why it’s a problem

Knob-and-tube isn’t inherently dangerous when undisturbed and original. The problem is what’s happened in the 80+ years since installation:

  1. Insulation has been added on top of it. Original installations relied on air space around the conductors for cooling. When attic insulation gets blown in over knob-and-tube, the conductors overheat. This is the single biggest fire risk and the reason most insurance carriers require remediation.
  2. Cloth/rubber insulation has degraded. It cracks, flakes, and exposes bare conductor in places.
  3. Modifications by non-electricians over decades. Junctions made with electrical tape (instead of the proper porcelain or ceramic boxes), splices buried in walls, branch circuits added without grounding.
  4. No equipment grounding. Two-prong outlets throughout, which means no ground for modern appliances and electronics.
  5. Modern HVAC loads on old wiring. Homeowners add window AC units or space heaters that draw real current through conductors never designed for it. If you’re upgrading your cooling, talk to Climate Pros SD about a properly sized system — a modern mini split draws a fraction of what a window unit does and runs on a dedicated circuit we install.

What insurance carriers ask

Most carriers in 2025–2026 will:

  • Ask about wiring type on the application
  • Refuse to write new policies on homes with active knob-and-tube
  • Non-renew existing policies if discovered
  • Sometimes accept knob-and-tube only if it’s confirmed disconnected and abandoned (still in walls but not energized)

Aluminum branch wiring

What it is

Between roughly 1965 and 1973, copper prices spiked. Aluminum branch circuit wire — for 15-amp and 20-amp circuits in residential homes — became common as a cost-saving substitute. The brand-name conductor is often labeled “AL” or has an aluminum-colored sheath. Aluminum is a slightly larger gauge than copper for the same amperage rating (12 AWG aluminum equals about 14 AWG copper).

Where you’ll find it in San Diego

Tract homes built between 1965 and 1973 in:

  • Older parts of Chula Vista west of I-805
  • 1960s-era San Diego neighborhoods like Allied Gardens, Tierrasanta (some sections)
  • Older El Cajon, Spring Valley, and La Mesa tract homes
  • Some 1970s Escondido and Poway construction

Why it’s a problem

Aluminum branch wire isn’t inherently dangerous either — it conducts electricity fine. The problem is the connection points:

  1. Aluminum oxidizes at terminations. The oxide layer is electrically resistant, which causes heat at connections.
  2. Aluminum expands and contracts more than copper with temperature changes, which loosens connections over time.
  3. Galvanic corrosion occurs where aluminum touches copper directly, accelerating connection failure.

The result: connections at outlets, switches, and junction boxes overheat. The plastic of the outlet body discolors and softens. Over years, scorching and arcing can occur. Documented residential fires from aluminum branch wiring are the basis for the insurance flag.

Close-up of aluminum branch wiring connection inside an outlet box showing the silver aluminum conductor wrapped around a brass terminal screw
Aluminum branch wiring (silver, larger gauge for the same amperage) was widely used 1965–1973. The connection points are where it fails. Photo: Bright Pro Electric.

What insurance carriers ask

Carriers approach aluminum branch wiring two ways:

  1. Some refuse coverage entirely until full remediation
  2. Some accept it with documented COPALUM crimp connections at every termination — a UL-listed remediation method that’s far cheaper than full rewiring

Aluminum service entrance and aluminum to large appliances (range, dryer) are usually fine and not the concern. The issue is specifically aluminum on 15-amp and 20-amp branch circuits.

What are your remediation options?

For both wiring types, you have options between “nothing” and “rewire the whole house.” We’ll quote the right scope for your specific situation.

Knob-and-tube remediation

  • Full rewire — the right answer for most homes. Pull new copper Romex through attic, crawlspace, and wall fish-tape openings. Abandon the old K&T in place.
  • Partial rewire — sometimes only the original sections of an addition-modified house need work. We can scope phase-by-phase.
  • Disconnect and abandon — if certain K&T circuits aren’t needed (an old kitchen or bathroom that’s been remodeled), we can disconnect and document for insurance.

Aluminum branch remediation

  • COPALUM crimp connections at every termination — UL-listed, accepted by most carriers. About $35–$75 per device.
  • AlumiConn lug connectors — a similar listed solution, sometimes used where COPALUM tooling isn’t available.
  • Full rewire — the most expensive option, but a clean-slate approach if the home is already being remodeled.

What it costs

Typical scopes for a 1,500–2,500 sq ft single-family home:

  • COPALUM aluminum remediation: $4,500–$9,500 depending on device count
  • Partial rewire (one wing or floor): $3,500–$8,000
  • Whole-home rewire: $12,000–$28,000+ depending on access, wall finish, and drywall scope

Free in-home assessment and a written scope before any commitment.

Will I have to move out?

Almost never. We rewire in phases — one circuit or one room at a time — so the rest of the house stays powered. Most clients stay in the home through the entire project. We let you know which rooms will be without power and for how long.

How much drywall damage should you expect?

Less than people fear. We pull through attic, crawlspace, and existing chases wherever possible, and use fish tape through walls when not. Most rewires need 4–8 small drywall openings per room (4-inch round to 6×6 square typical). We don’t do drywall repair ourselves but can refer a finisher.

Frequently asked questions

How much does a whole-home rewire cost in San Diego?

A full rewire for a 1,500–2,500 sq ft single-family home costs $12,000 to $28,000+ depending on wall access, finish work, and the complexity of the existing wiring. Partial rewires (one wing or floor) run $3,500 to $8,000.

Can I get insurance with knob-and-tube wiring?

Most carriers in 2025–2026 won’t write new policies on homes with active knob-and-tube wiring. Some accept it only if the knob-and-tube is confirmed disconnected and abandoned in place. You’ll likely need remediation before coverage.

What’s a COPALUM crimp and does it really fix aluminum wiring?

A COPALUM crimp is a UL-listed connection method that bonds aluminum wire to a short copper pigtail at every outlet, switch, and junction. It addresses the oxidation and thermal expansion issues at termination points. Most insurance carriers accept COPALUM remediation without requiring a full rewire. It costs $4,500 to $9,500 for a typical home.

Do I have to move out during a rewire?

Almost never. Rewiring is done in phases — one room or circuit at a time — so the rest of the house stays powered. Most homeowners stay in the home throughout the project.

A rewire usually means a panel upgrade too. Our panel upgrade cost guide covers pricing, permit process, and what SDG&E coordination looks like. If your home has a Federal Pacific or Zinsco panel alongside the old wiring, read our FPE and Zinsco replacement guide for the specific failure risks those panels carry.

Service area

Whole-home rewiring and aluminum remediation across San Diego County. Older inland tracts in El Cajon, Spring Valley, and the older parts of Chula Vista and Escondido are where we see the most aluminum branch work. Knob-and-tube comes up in coastal beach bungalows and older central San Diego neighborhoods.

See our full whole-home rewiring service page or call (858) 400-8901 for a free assessment.