Why Are My Lights Flickering?

Do you have flickering lights from time to time? They’re one of life’s little annoyances, but they can also be a sign of a bigger problem. I’m an electrician, and I’ve been living with a flickering fluorescent light for weeks now. In my defense, it’s in a closet, but every time I flip on the light and see that strobe effect, I kick myself and add “fix the light” to my ever-lengthening to-do list.

Based on prior dealings with this light (which I really should just replace already), I know the situation isn’t dire. But if you have flickering lights, you might not be so lucky. They could be a signal that something is wrong with your light or the electrical circuit feeding the fixture. Flicker can even cause health problems like fatigue, blurred vision and migraines.

So, why do lights flicker, and what can you do about it? (I definitely don’t recommend ignoring it.) Ahead, I enlisted a fellow electrician to help you diagnose and eliminate annoying flicker. The solution is usually simple, but if things get complicated, don’t hesitate to call a licensed electrician.

What Causes Lights to Flicker?

Why do lights flicker? Well, it depends. “It can be a loose bulb, overloaded circuit, loose wiring, fluctuations in voltage, or even an incompatible dimmer, to name a few [possible reasons],” says Johnny Sharif, a licensed electrician and virtual electrical expert with Frontdoor, an app service that connects homeowners to experienced, on-staff experts for help with home maintenance issues.

Here are some reasons your lights might flicker, starting with the easiest to fix:

• Loose or bad bulb. The first thing to check is the bulb, aka lamp. Turn off the fixture and allow it to cool. If the bulb is loose, gently tighten it. If that doesn’t work, try replacing the bulb. Fluorescent lamps flicker when they’re near the end of their lifespan, so now’s a great time to swap out those tubes for a long-lasting LED.
• Bad socket. In a basic light socket, the silver threads are the neutral connection, and the brass flap that the bulb’s base makes contact with is the hot. If either of these connection points gets old and corroded, your light could flicker. If that happens, replace the fixture.
• Incompatible dimmer switch. Dimmers are notorious for flickering, especially if you have an older switch or incompatible LED bulb. If it’s the dimmer, Sharif says you can tell because you’ll see inconsistent dimming and flicker. “You can also look up the bulb’s model number online, on its packaging, or in the manufacturer’s spec sheet, and that can help you determine its compatibility with your dimmer,” Sharif says.
• Loose connections or old switches. Basic snap switches don’t last forever. Springs wear out, and wire connections can loosen over time. If you’re comfortable, turn off the power and check that the switch is properly connected and tight. (Always verify the power is off with a non-contact voltage tester first.) Also, “look at the switch itself,” Sharif says. “If it’s an old switch, it may not be compatible with newer LED bulbs, and it may be time to upgrade it.”
• Overloaded circuit. Too many things running at once can cause flicker. Do your lights flicker when an appliance starts up? Do they flicker when you run your vacuum cleaner, lights and microwave all at the same time? Redistribute the loads and see if that helps.
• Wiring problems. If the flickering is all over the house, it’s more likely to be a problem with your electrical service panel, particularly a loose neutral. Have an electrician check it out.
• Voltage fluctuations. Your house gets 240 volts of power from the electrical transformer outside. If there’s a loose connection there, at the meter or elsewhere along the path into your home, you could lose a leg of power (meaning you’re only getting 120 volts). Sometimes, half of your house will go out, but another symptom is flickering lights. Call the utility.

Are Flickering Lights Dangerous?

In the case of a loose bulb or outdated dimmer switch, no. However, loose connections and other wiring problems can cause arcing, which is a dangerous situation that is an immediate fire risk. Electricity always wants to keep moving, and it will jump between the loose connections, easily igniting nearby combustible materials or creating a shock hazard.

The health problems associated with flickering lights are no joke, either. All lights, from incandescent to fluorescent to LED, flicker to some degree, because we use alternating current (AC) to power them. Our eyes don’t necessarily register this normal flicker, but abnormal flickering due to problems with your electrical system can cause mild to severe health issues like dizziness, headaches and seizures in certain people.

Don’t take my lead with my closet light flicker: Fix your lights.

About the Expert

Johnny Sharif is a licensed electrician and virtual electrical expert at Frontdoor, a home care and maintenance app service that connects people and professional technicians via tech-enhanced video chats. Sharif has nearly 20 years of experience in the electrical industry.