Why Do GFCI Outlets Trip and How to Fix It?

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.

GFCI outlets trip when they detect a ground fault – a difference in current between the hot and neutral wires – usually caused by moisture, a damaged appliance, worn wiring, or a failing GFCI device. Common causes include wet locations (bathrooms, kitchens, garages, outdoor outlets), older appliances with deteriorated insulation, and GFCIs that have reached the end of their 10–15 year lifespan. If a GFCI trips immediately when you plug in a specific appliance, the appliance is likely faulty. If it trips randomly or won't reset with nothing plugged in, the GFCI or wiring may need replacement. In Santa Clara County, GFCI outlet replacement typically costs $150–$350 per outlet including labor.

Last week I got a call from a Mountain View homeowner. Her bathroom GFCI kept tripping every morning. She'd reset it, use her hairdryer for 30 seconds and – pop – it tripped again. Reset, blow-dry, trip. Over and over.

She was sure the outlet was bad. Turned out the hairdryer had a frayed cord near the plug. The exposed wire was creating a tiny ground fault every time she moved it. The GFCI was doing exactly what it's supposed to do: protect her from shock.

That's the thing about GFCIs. When they trip, they're telling you something. Sometimes it's the appliance. Sometimes it's moisture. Sometimes the GFCI itself is tired. And sometimes – less often, but serious – it's a wiring problem.

Here's how to sort out which one you're dealing with in a Santa Clara County home.

If Your GFCI Keeps Tripping, Check These First

All of these are external checks. Don't open outlets or touch bare wires.

Unplug everything from that GFCI and any outlets it feeds. Reset it. If it stays on with nothing plugged in, the issue is likely one of the devices, not the outlet.
Plug in one device at a time. The one that makes it trip right away is your suspect. Inspect its cord and plug for damage or fraying.
Check for moisture. In bathrooms, kitchens, garages, and outdoor spots around San Jose, Sunnyvale, and Santa Clara, GFCIs trip a lot because of water. If the outlet or cover is damp, let it dry completely and try again.
Look at the outlet. Is it loose, cracked, or physically damaged? A loose GFCI in a tile backsplash or stucco wall is asking for trouble.
Use the TEST / RESET buttons. Press TEST – it should trip instantly. Press RESET – it should click and hold. If TEST does nothing, or RESET won't stay in, the GFCI is worn out.
Check downstream outlets. One GFCI in a Campbell or Milpitas home may protect several bathroom or garage outlets. A problem at any downstream outlet can trip the main GFCI.

If everything is unplugged and it still won't reset, or it trips immediately with no load, the GFCI itself is likely failed or there's a wiring/moisture issue behind it.

Why GFCI Outlets Trip

GFCI stands for Ground Fault Circuit Interrupter. It constantly compares the current going out on the hot wire to the current returning on the neutral. If more than about 4–6 milliamps go missing, it assumes that current is leaking somewhere it shouldn't (like through a person) and shuts off power in about 25–30 milliseconds.

Most common reasons they trip:

Faulty Appliance or Device

This is number one.

Damaged cords
Worn insulation
Internal shorts in older appliances

Hairdryers, shavers, phone chargers, coffee makers, toaster ovens, and power tools are frequent offenders. Once they get to 10+ years, they're much more likely to start causing nuisance trips in homes around Los Altos, Morgan Hill, and Gilroy.

Moisture in the Outlet or Wiring

Water conducts electricity and gives current a new path.

We see this constantly in:

Outdoor outlets without proper in-use covers
Bathroom receptacles near sinks and tubs
Kitchen outlets along sink runs
Garage outlets exposed to humidity or washing

If the GFCI trips after rain in Campbell, or right after a hot shower in Evergreen, moisture is a top suspect.

Worn-Out GFCI Device

GFCIs are not forever. Typical lifespan: 10–15 years.

Homes from the 1990s and early 2000s in Milpitas, Santa Clara, and Los Altos often still have original GFCIs. Over time, the internal electronics drift. They can:

Trip too easily (nuisance trips), or
Fail to trip when they should (more dangerous)

If yours is 15+ years old and acting weird, replacement is cheap insurance.

Overloaded Circuit

Technically, the breaker protects against overload, not the GFCI. But if you run a space heater, hairdryer, and curling iron on one bathroom circuit, you get heat, voltage drops, and sometimes ground faults that the GFCI sees.

If the GFCI only trips when "everything is on," you may be pushing that circuit too hard, especially in older San Jose or Sunnyvale homes with minimal bathroom circuits.

Damaged or Deteriorated Wiring

In homes built before ~1980, especially in parts of San Jose, Santa Clara, and Hollister, we still see:

Cloth-insulated wiring
Early NM cable with brittle jackets
Old splices buried in walls

When insulation breaks down, you can get intermittent ground faults that trip GFCIs at random.

Incorrectly Wired GFCI

If a GFCI is wired wrong – line/load reversed, missing neutral, improper bonding – it can:

Trip constantly
Fail to reset
Or appear to work but not protect anything

This usually shows up right after installation. If your GFCI worked fine for years and suddenly went crazy, wiring error is less likely than moisture, age, or a device problem.

Stop and Call an Electrician If…

DIY stops here:

The GFCI won't reset with everything unplugged
It trips immediately every time you reset it, with no load
The outlet feels warm or hot to the touch
You see melted plastic, scorch marks, or discoloration around it
You smell burning plastic or a sharp "electrical" odor
It sparks when you plug something in or press reset
The problem started right after remodeling or wall work
Multiple outlets on that circuit are acting up
The outlet is physically cracked or loose in the wall
You're not confident chasing which device or outlet is to blame

At that point, you're into "find the underlying fault," not just "reset it again."

How Electricians Diagnose and Fix GFCI Problems

Here's what we actually do in homes around Mountain View, Santa Clara, and Morgan Hill.

1. Test the GFCI Device

We use a proper GFCI tester to:

Simulate a ground fault
Verify it trips within the allowed time window
Check that power is removed from both hot and neutral

If it fails this test, it's done and gets replaced.

2. Test Appliances and Devices

We plug in suspect appliances one at a time and, when needed, check with a multimeter for leakage or insulation issues. If the GFCI only trips with a specific device, the cheapest fix is usually a new device, not electrical work.

3. Inspect the Wiring

If the GFCI trips with nothing plugged in:

Open the box
Check line/load connections
Look for nicked insulation, cramped conductors, or signs of water
Tighten or remake any loose splices
Confirm grounding and bonding

In older Morgan Hill and Hollister homes, we often see brittle cloth insulation where bare copper can touch the box or other conductors. That gets fixed by re-terminating, sleeving, or running new cable to that point.

4. Check Downstream Outlets

One GFCI in a Campbell bathroom might protect 2–3 other bathrooms, or a garage in a 1990s San Jose house. We:

Trace the circuit
Open and test each downstream device
Fix loose connections or damaged outlets that can be tripping the upstream GFCI

5. Replace the GFCI (When It's the Culprit)

If testing shows the device is worn out:

Swap in a new, code-rated GFCI
Verify correct line/load wiring
Test with both the built-in TEST button and a tester
Confirm downstream outlets are protected

Typical replacement time: 20–30 minutes. Typical cost in Santa Clara County: $150–$350 per outlet depending on location and access.

6. Add Missing GFCI Protection

California code now requires GFCI protection in:

Bathrooms
Kitchens (certain countertop circuits)
Garages
Unfinished basements and crawlspaces
Outdoors and similar damp areas

If your Campbell, Sunnyvale, or Gilroy home was built before ~2000, you may have locations that still need GFCIs. We can:

Install GFCI outlets at the first receptacle on each circuit, or
Install GFCI breakers in the panel to protect entire circuits (typically $200–$400 installed per breaker).

GFCI Outlet FAQs

Can I replace a GFCI outlet myself?

If you're comfortable shutting off breakers, verifying no power, and following the wiring diagram, you technically can. But mis-wiring line and load is easy and leaves you unprotected. For most homeowners, it's worth having an electrician spend 20–30 minutes and know it's right.

How often should I test my GFCI outlets?

Monthly. Press TEST – the outlet should trip and cut power. Press RESET – it should click and restore power. If TEST doesn't trip it, or RESET won't stay in, replace the GFCI. At that point, it's not doing its job.

Why does my outdoor GFCI trip when it rains?

Moisture is getting into the box or onto the device. Common issues:

No in-use (bubble) cover
Broken or missing gasket
Box not sealed to stucco or siding

Sometimes the fix is a proper weatherproof cover. Sometimes we have to replace the outlet and clean up the box and connections.

Can I use a GFCI extension cord instead of replacing the outlet?

Fine for temporary use (yard tools, job sites). Not a permanent solution and not a substitute for required GFCI protection at fixed outlets. If code requires a GFCI outlet, install one.

Why does my GFCI trip when I use the vacuum cleaner?

Either:

The vacuum has a ground fault (damaged cord, motor issue), or
You're overloading that circuit with other appliances

Try the vacuum alone on that outlet. If it still trips, the vacuum is suspect. If it only trips when other loads are running, you're overloading that branch.

Do GFCI outlets protect against power surges?

No. GFCIs protect against ground faults (shock). Surge strips and whole-house surge protectors protect against voltage spikes. Different tools, different jobs.

How long do GFCI outlets last?

On average, 10–15 years. After that, the internal electronics drift. If you're in a 1990s Los Altos or Milpitas home and still have original GFCIs, it's time to think about replacing them.

Can a GFCI outlet go bad without tripping?

Yes. A failed GFCI can keep passing power but stop detecting faults. That's why the TEST button (and a real tester) matters. If TEST doesn't shut it off, it has failed and you effectively have no protection.

Why does my bathroom GFCI trip when I use an outlet in another bathroom?

Very common wiring pattern. One GFCI (often in the first bathroom) protects other bathrooms on the same circuit. A problem in the second or third bathroom – moisture, bad device, loose connection – trips the main GFCI.

Will a GFCI trip if I drop a hairdryer in the sink?

Yes, and quickly. That's exactly what it's designed for: to cut power fast enough to prevent a fatal shock.

Why Homeowners in Santa Clara County Call Watson's for GFCI Issues

Fast diagnosis – we usually identify if it's the outlet, the appliance, or the wiring within 15–20 minutes.
We use proper GFCI testers and meters, not just the reset button.
Experienced with older Bay Area wiring: cloth-insulated, aluminum, and undersized bathroom/kitchen circuits.
We test and, if needed, repair downstream outlets protected by the GFCI, not just swap the device and leave.
Honest calls – if the fix is "replace your $20 toaster," we'll tell you that instead of selling work you don't need.
Clean replacements with minimal wall damage and correct weatherproofing where needed.
We verify correct line/load wiring and test every GFCI before we leave.
Licensed (C-10), insured, and familiar with California GFCI code requirements.