Warning Signs of Bad Wiring in Your Home

This article is general safety information for California homeowners. It is not legal, insurance, or code advice. Always confirm requirements with your local building department, utility, insurer, and a licensed electrician.

Bad wiring often shows up as flickering lights, warm or discolored outlets, frequent breaker trips, burning smells, or buzzing and crackling sounds. Homes built before 1980 in Santa Clara County and the wider Bay Area commonly have outdated wiring (aluminum, cloth‑insulated, knob‑and‑tube, or undersized circuits) that can't safely handle modern electrical loads. If you're seeing more than one of these warning signs, call a licensed electrician — bad wiring is a leading cause of house fires in California.

Last Tuesday I got a call from a Willow Glen homeowner. Her GFCI outlet kept tripping every time it rained. When I pulled the outdoor box, it was full of water and the wiring inside the wall had started to cook. By the time we opened it up, the insulation was melted in three spots.

She caught it early. A lot of people don't.

Bad wiring doesn't announce itself with sirens. It taps you on the shoulder: a flicker here, a warm outlet there, a breaker that trips "more than it used to." Most homeowners ignore those signs until something fails completely.

Here's what to watch for and what to do about it in a Santa Clara County home.

If You're Seeing Warning Signs, Check These First

All of these are external checks. Don't open panels or junction boxes yourself.

Test outlets with a small lamp. Does it flicker or feel loose when you plug it in?
Feel outlet and switch covers. They should be room temperature, not warm or hot.
Listen close. Any buzzing, crackling, or popping near outlets, switches, or fixtures is a red flag.
Watch your breakers. Do the same ones trip more than once a month under normal use?
Smell near outlets and the panel. Burning, plastic, or "hot" smells are urgent.
Look for discoloration. Brown, yellow, or black marks around outlets, switches, or light fixtures.
Check lights when big loads start. Do lights dim when the microwave, AC, or hair dryer kicks on?

If you find issues in multiple rooms or circuits, it's usually not "one bad outlet." It's wiring or circuit design.

Why This Happens

Old Wiring Materials

A lot of Santa Clara County's housing stock is older. In San Jose, Campbell, and parts of Los Gatos, you still see:

Cloth‑insulated wiring (pre‑1960).
The cloth dries out, cracks, and falls apart, leaving bare copper exposed. Anywhere there's heat (attics, light fixtures, around recessed cans), it deteriorates faster.
Aluminum wiring (1960s–1970s).
Common in certain tracts around San Jose and Sunnyvale. Aluminum expands and contracts more than copper when it heats and cools. Over time, that movement loosens connections at outlets, switches, and splices. Loose connections create resistance, resistance creates heat, and heat is what starts fires.
Knob‑and‑tube wiring (pre‑1950).
You still find this in some older San Jose and Willow Glen homes and the occasional Los Gatos cottage. It was never designed for grounded 3‑prong outlets or today's power demand. It's ungrounded, often modified poorly over the decades, and usually past its intended life.

Undersized Circuits

Plenty of otherwise "good" wiring is just on circuits that are too small for modern loads.

A standard 15A circuit can safely deliver 1,800 watts.
A typical microwave uses 1,200W.
A toaster uses 1,000W.

Run both at once on the same 15A kitchen circuit and you've already overloaded it.

We see this a lot in older Campbell, Santa Clara, and Milpitas homes: one or two general kitchen circuits feeding everything. The wiring itself might be fine, but the circuits are undersized for how people actually live now. The fix is adding properly sized 20A dedicated circuits, not ripping the whole house apart.

Poor Connections

Even good wire can be dangerous if the connections are bad.

Backstabbed outlets. Wires pushed into the back of the receptacle instead of wrapped on screws. Those spring connections loosen over time, creating heat and arcing.
Loose wire nuts. Poorly twisted splices inside junction boxes.
Corroded terminals. Especially in damp locations like exterior walls and garages.

Loose = resistance = heat. Heat breaks down insulation and, eventually, something arcs or cooks.

Overloaded Circuits

You can have perfectly fine wiring and still overload a circuit by what you plug into it:

Space heaters
Window AC units
Multiple high‑draw devices on one power strip

When that circuit trips repeatedly, the breaker is actually doing its job: protecting the wire. The problem is how much you're asking from that one circuit.

Stop and Call an Electrician If…

These aren't "keep an eye on it" signs. They're "pick up the phone" signs.

Outlets or switches are warm or hot to the touch.
You smell burning plastic or a sharp "electrical" odor.
You see sparks when plugging in devices.
Outlet or switch plates show discoloration or scorch marks.
The same breaker trips repeatedly (more than 2–3 times a month).
You get a shock or tingle from outlets, appliances, or switches.
Lights flicker or dim when large appliances turn on.
You hear buzzing or crackling from outlets, switches, or the panel.
GFCI outlets won't reset or trip immediately with nothing plugged in.
Multiple rooms lose power with no tripped breaker in the panel.

Any of these means your wiring or connections need professional attention now, especially in older homes around Willow Glen, Campbell, Sunnyvale, and Palo Alto.

How Electricians Fix Bad Wiring

Electrical Inspection and Testing

First step is always diagnosis.

Test outlets and switches for voltage issues.
Open selected devices and junctions to inspect connections.
Use thermal imaging on suspect circuits (especially with aluminum wiring) to find hot spots before opening walls.

For most Santa Clara County homes, this is a 1–2 hour visit.

If you're buying or selling, this is our $179 Home Electrical Safety & Capacity Check: outlet testing, panel inspection, basic load review, and a written report of hazards and priorities.

Circuit Mapping

Older San Jose, Los Gatos, and Gilroy homes often have "creative" circuit layouts:

Bedrooms and bathrooms sharing a circuit with the garage
Kitchen outlets tied in with exterior lights
One breaker feeding half the house

We trace circuits to see exactly what's on each breaker. That tells us where you're overloaded and what needs to be moved or split.

Rewiring Problem Areas

If we find damaged or clearly unsafe wiring, we replace it. That might mean:

One bad circuit
One or two rooms
Or, in rough cases, most of the house

Rough price ranges in Santa Clara County:

Single circuit replacement: $800–$2,000 (access‑dependent)
Partial rewiring (1–3 rooms): $2,500–$6,000
Full rewiring: $8,000–$25,000+ depending on size, access, and finish work

Full rewires are usually reserved for:

Widespread knob‑and‑tube
Severely degraded cloth wiring
Major remodels where walls are already open

Aluminum Wiring Remediation

Aluminum branch wiring doesn't always need full replacement. The main issue is at the connections.

One common fix is installing crimped COPALUM‑type connectors or equivalent approved methods at:

Every outlet
Every switch
Every junction box

That bonds the aluminum to copper pigtails, stabilizes the connection, and addresses the expansion/contraction problem.

Typical ranges we see:

$2,000–$8,000 depending on number of devices and accessibility.

Adding Dedicated Circuits

Sometimes the wiring is fine; you just have too much on a few circuits. In those cases we add dedicated circuits for high-draw appliances or areas.

Typical cost: $800–$2,000 per circuit depending on:

Accessibility (attic/crawlspace vs cutting through walls)
Distance from panel to destination
Wire size needed (12 AWG for 20A vs 10 AWG for 30A)
Complexity of fishing wires through existing framing

Common dedicated circuit additions:

Kitchen appliances (microwave, toaster oven, coffee maker)
Window AC units
Garage/workshop outlets
Home office circuits
Exterior outlets

These prices assume:

Your main panel has breaker space and capacity
We're not opening half the house to fish wires

If the panel is full, you may need:

A subpanel ($1,800–$3,500) or
A main panel upgrade ($4,500–$9,000 for typical 100A → 200A)

Do You Need Permits?

In Santa Clara County, yes for anything beyond basic device swaps.

Permits are typically required for:

Adding new circuits
Replacing wiring in walls or ceilings
Upgrading main panels or subpanels
Aluminum wiring remediation projects

Minor repairs (like swapping a bad outlet or switch on an existing circuit) usually don't require permits, but check your city's exact rules.

Typical permit costs:

Most cities (Campbell, San Jose, Los Gatos, Sunnyvale, Santa Clara): about $700–$900
Some smaller/simple scopes may be closer to $650
Palo Alto: commonly around $1,900

Inspectors will check:

Correct wire sizing
Proper grounding and bonding
Quality of connections and junctions
GFCI/AFCI protection where required
Box fill, support, and accessibility
Overall code compliance

It's a second set of eyes making sure the work is actually safe and up to California code.

FAQs

How do I know if I have aluminum wiring?

Check where cables enter your panel. Aluminum cables are usually stamped "AL" or "ALUM" on the jacket and look silver, not copper‑colored. You can also look in an accessible attic or crawlspace. If you're not sure, a licensed electrician can confirm in about five minutes.

Is aluminum wiring dangerous?

It's not the metal itself, it's the connections. Aluminum moves more with heat than copper. That movement can loosen terminations over time, especially on old devices not rated for aluminum. Loose = hot = unsafe. Properly remediated aluminum wiring with approved connectors and regular inspection can be safe.

Can I just replace warm outlets myself?

Warm outlets mean a problem behind the cover – loose connection, damaged conductor, or overloaded circuit. Swapping the device without fixing the cause is like changing a tire on a car with a bent axle. Have an electrician find the real issue first.

How much does it cost to rewire a house in Santa Clara County?

Rough ranges:

Full rewire: $8,000–$25,000+ depending on size, access (attic/crawlspace vs slab), and finish level.
Partial (1–3 rooms or a few circuits): $2,500–$6,000.

Permits and inspection are part of that; patch/paint can be bundled or handled by a drywall contractor.

Will rewiring require opening walls?

Sometimes. If we can route new wire through accessible attics, basements, or crawlspaces, we can often avoid most wall damage. If everything is buried in inaccessible walls (common in older Palo Alto and Sunnyvale homes), we cut small, strategic openings, run new wire, then patch and paint. The goal is minimal disruption.

Is cloth‑insulated wiring safe?

Not long‑term. Cloth insulation breaks down with age and heat. Once it cracks and falls off, bare copper is exposed inside walls and boxes. That's a shock and fire risk. When we find significant cloth wiring in a home, we usually recommend a plan to replace it.

How long does rewiring take?

Ballpark timelines:

Single circuit: 1 day
Partial rewiring (1–3 rooms): 2–4 days
Full house: 1–3 weeks

Add 1–6 weeks for permits in Santa Clara County, plus a bit for inspections and repairs.

Can I get insurance with old wiring?

It depends on the carrier and the wiring type. Some insurers won't touch homes with active knob‑and‑tube or unremediated aluminum. Others will, but with higher premiums or conditions. When people hit roadblocks getting coverage in San Jose, Los Gatos, or Gilroy, rewiring or aluminum remediation is often what unlocks standard coverage again.

What's the difference between bad wiring and an overloaded circuit?

Bad wiring: Damaged insulation, loose connections, improper splices, degraded materials, or undersized wire. Needs repair or replacement.
Overloaded circuit: Too many devices on one properly wired circuit. The wiring might be fine – the load isn't.

Both can trip breakers and cause symptoms. The fixes are different, which is why diagnosis matters.

Do LED lights fix flickering problems?

Sometimes. LEDs draw less power and are less sensitive to small voltage drops, so they can help with mild dimming on long runs. But if flickering is caused by loose connections, bad splices, damaged wiring, or an undersized panel, LEDs are a Band‑Aid on a deeper issue.

Why Homeowners in Santa Clara County Call Watson's

Experienced with aluminum, cloth‑insulated, and knob‑and‑tube wiring in older Bay Area homes from Willow Glen and Rose Garden to Los Gatos and Sunnyvale.
We handle permits and inspections from start to finish so you're not playing go‑between.
Honest assessments – we don't push full rewires when targeted fixes or partial work will solve the real problem.
Use thermal imaging and other diagnostic tools to find issues before we start cutting into walls.
Clean work with minimal wall damage and coordinated drywall patching when needed.
Licensed (C‑10), insured, and up to date on California electrical code and Santa Clara County practices.
Gilroy‑based and serving all of Santa Clara County.

Need Your Wiring Checked?

If you're seeing warning signs – or you're buying a home with older wiring – Watson's offers a $179 Home Electrical Safety & Capacity Check that includes outlet testing, wiring inspection, and a clear, prioritized report on what needs attention.

Call or text Watson's Charging Stations & Electric at (408) 642‑6547 to schedule your wiring inspection. We serve Santa Clara County.