A GFCI trips in response to a ground fault. How can the GFCI tell that a ground fault has occurred? It looks at the incoming and outgoing current.
A current leak as small as 5mA is enough to trip the GFCI.
But how does that relate to power outages? Why would a blackout trip the outlet? The following may explain this phenomenon:
1). You Have A Bad GFCI
Bad GFCIs are prone to nuisance tripping. Some of them have factory defects. Others develop faults because of exposure to excess moisture, dust, debris, UV light, and more. A bad GFCI will trip with or without a power outage.
It will also fail the routine tests homeowners usually perform. Keep the age in mind. GFCI outlets have a lifespan of seven to ten years. Once they wear out, nuisance tripping will become a common occurrence.
2). You Don’t Have Power
Are you sure the GFCI tripped? GFCIs deprive the outlet of power when they trip. Any active appliance will stop working once the GFCI trips. People interpret the absence of power as a sign of tripping.
But are you sure your power has returned? Maybe the GFCI has stopped working because your home doesn’t have power. You can confirm by checking the GFCI outlet. The RESET button will pop out when it trips.
You should also check the breaker. A defective or tripped breaker will deprive the GFCI of power.
3). The Appliance Has A Fault
GFCIs can trip because of a connected appliance. What if you don’t have any appliances in the receptacle? Contractors typically use one GFCI to protect multiple outlets downstream.
Any defective appliance plugged into the outlets downstream can trip the GFCI upstream.
The GFCI may trip because of poor wiring or some sort of current leak inside the connected appliance.
4). The GFCI Responded To Fluctuations
GFCIs can trip because of fluctuations when the power returns.
If the GFCI tripped because of wild fluctuations that occurred before the outage, you should call the utility company. Ask them to investigate the issue. Drastic fluctuations are dangerous. The spikes and surges can damage your equipment.
Keep in mind that GFCIs respond to ground faults. They won’t protect your equipment from surges and spikes.
5). You Wired The GFCI Poorly
This is why contractors discourage laypeople from doing their own wiring. You’re more likely to make a mistake. Leviton has a manual showing consumers how to wire their GFCI. If you don’t understand those diagrams, you shouldn’t wire a GFCI.
People think the worst-case scenario is a GFCI that trips incessantly for no apparent reason. But that is actually the best-case scenario. The worst-case scenario is a GFCI that doesn’t trip at all.
Troubleshooting GFCI Outlets That Trip After Power Outage
- Start with the other outlets. Are they also dead? A tripped GFCI will de-energize all the outlets it protects downstream. But what about the outlets outside the GFCI’s reach? Use a voltage tester to determine whether they have a flowing current. You can also connect an appliance. Does it work when you flip the switch to the on position?
- If all the outlets are dead, something else is going on. In other words, the power outage keeps tripping the breaker. You can confirm this suspicion by checking the lights. If they won’t turn on even when the power returns, you have a bigger problem on your hands.
- Find the electrical panel and check the circuit breaker. Did the breaker trip? If so, reset it. What about the fuse? If it blew, you should replace it. Breakers are tricky because some of them trip during every power outage because of a fault. Therefore, resetting them isn’t enough. They will either trip again or start a fire. Look out for worrisome symptoms, such as a burning smell, overheating, and visible damage.
- What if you’ve reset the breaker, but the problem has persisted? Quisure blames the under-voltage release. They have a picture of the device. You find the part on the air switch. As the name suggests, it responds to under-voltage. The voltage tends to fall before and during a power outage, tripping the breaker. If the under-voltage protection has become a nuisance because of incessant tripping, remove it. But this requires an expert. The electrician can recommend a suitable replacement that doesn’t include under-voltage protection.
- Turn your attention to the GFCI outlet. Push the RESET button. If the GFCI won’t reset, check for and resolve loose connections. This involves cutting the power and removing the outlet from the electrical box. This allows you to tighten the terminal screws. You should also check the stab-in connections. Are they firm? If they feel loose, don’t just re-insert them. Strip the wires and use the terminal screws instead of the stab-in connections.
- Don’t ignore the health of the wires. Replace lines with broken or worn-out insulation. Otherwise, they will contribute to the incessant tripping by causing ground faults.
- If you have appliances connected to one or more outlets downstream, disconnect them. If the nuisance tripping stops (during a power outage), the appliances are at fault. Which device is plugged in whenever the GFCI trips? Inspect that appliance. Is the power cord frayed? Do you see burn marks inside the plug? Does it have loose connections? Some devices are more complicated than others. It might be easier to replace the defective appliance.
- Hire a technician and ask them to check the GFCI’s wiring. Maybe you made a mistake during installation. The technician can identify the wiring error. If the GFCI has reached the end of its lifespan, the technician will tell you to get a replacement.
- Talk to your utility company about fluctuations in the power supply. The company’s technicians will identify and resolve the problem on the grid.
You can ask the utility company’s electricians to inspect your electrical system for current leaks, especially if they’ve failed to find any faults on the grid. Fluke recommends measuring the current leak with the help of a league current clamp meter.
Leakage current clamp meters can identify tiny current leaks. You perform the measurements by connecting the meter to the phase and neutral lines. This applies to single-phase circuits. With three-phase circuits, you will clamp every phase conductor as well as the neutral (if you find one).
Identifying the leg with the suspiciously high current leak is merely the first step. You must locate the equipment on that leg responsible for the leak. Some devices have surge suppression filters and capacitors that increase the capacitance.
The fault may lie with the total current leak from all the legs. You won’t know until you check. This job requires a qualified electrician. They can troubleshoot your home’s electrical system from top to bottom.
Naturally, you may incur hefty labor fees, especially if your electrician charges by the hour. The more time they spend troubleshooting your home, the more money you will pay in the long run. But those labor fees are worth it to identify the source of the nuisance tripping.