Lights Flickering in the House: One Bulb, One Room, or the Whole House

What flickering lights mean depends on how much of the house is doing it. One bulb or fixture usually points to the bulb or, with LEDs, a dimmer that doesn't suit it. One room or circuit points to a loose connection at a switch, outlet, or fixture, which the CPSC warns can lead to arcing, overheating, or a fire. The whole house, or the neighbors too, points to the electric utility: its lines, the connection at your meter, or the weather. NFPA lists flickering lights among the reasons to call a licensed electrician, so rule out the bulb and dimmer first; those are yours.

If half the house went dark, or some rooms are brighter than others, see half the house has no power, which treats bright lights as urgent. For a breaker that keeps tripping, see breaker keeps tripping; for dead bathroom or kitchen outlets, GFCI won't reset; and if the whole street is out, what to do when the power goes out.

Most Likely Causes

Check these in order, from one bulb out.

1. A loose, failing, or wrong bulb (one bulb). Signify, the company behind Philips Hue, lists a bulb that isn't screwed tightly into its socket, or loose fixture wiring, among the most frequent reasons LED bulbs flicker; its fix is to turn off the power and make sure both are secure. The ESFi adds that loose bulbs may overheat. NFPA says to use bulbs that match the recommended wattage on the lamp or fixture and to read an LED replacement's label to make sure it suits that fixture. If a recessed ceiling light keeps shutting itself off, it may be overheating: the CPSC notes recessed fixtures now have a device that cuts power when the fixture overheats, and that insulation filling the space over one can make it overheat. Turn it off and have a qualified electrician check it.
2. An LED on a dimmer that doesn't match it (one fixture, or everything on one dimmer). Leviton explains that an incandescent filament dims without hesitation, while an LED makes light with a semiconductor, so dimming one can bring buzzing, flickering, or lights that drop out. Feit Electric names the usual culprits: a dimmer not rated for LED loads, a bulb that isn't dimmable, or too few watts of LEDs to reach the dimmer's minimum load. Leviton says it can't recommend an incandescent-only dimmer with dimmable LEDs. Other controls count too: ENERGY STAR says to check with the maker of a photocell, motion sensor, or timer for compatibility with energy-efficient bulbs.
3. A loose connection at a switch, outlet, or fixture (one room or one circuit). When several lights flicker at once, LEDVANCE says the problem may be at the panel or connection points. A switch that makes its light flicker isn't working properly, and the CPSC says improperly operating switches and outlets may indicate an unsafe wiring condition: "A loose screw holding a wire or a worn out switch can lead to electrical arcing, overheating, or a fire." Its wiring guide adds that push-in backwire connections may tend to loosen and overheat. In a house wired between 1965 and the mid-1970s, the CPSC counts flickering lights among the signs of failing aluminum wiring connections and says not to try the repair yourself; our knob-and-tube guide explains why older K&T wiring needs a licensed electrician's evaluation.
4. A big appliance starting (a quick dip, then back to normal). PG&E says large loads such as a refrigerator, washer, or dryer turning on or off can cause short voltage sags, and you may notice one when the lights dim as the refrigerator starts. GE Lighting says refrigerators and clothes dryers can also put noise on the power line that makes LED lights elsewhere in the house flicker.
5. The utility's lines, the service connection, or the weather (the whole house, or the neighbors too). FPL calls interruptions shorter than a minute flickers and lists lightning, damaged equipment, vegetation, and animals among the causes. Santee Cooper, South Carolina's public power utility, says its substation breakers reset automatically after a tree limb or lightning strike, usually in less than a second. Flicker in the wind is different: the CPSC says it can come from bad contacts where your service entrance cable meets the utility's service drop, and Shenandoah Valley Electric Cooperative says loose connections on an overhead service can cause blinks whenever the wind sways the service wire.

Lights Dim When the AC Turns On: When It's Worth a Call

Goodman, an air conditioner maker, notes in a service bulletin that a compressor's high start-up current draw can drop the voltage 10 to 15 volts while it starts. PG&E calls the brief dip a big load causes a sag, which can last milliseconds and usually goes unnoticed, and Portland General Electric says your voltage constantly changes with the loads you and your neighbors use. Utilities flag these as worth a call:

• A noticeable dip every time the AC or heat pump starts, especially since one was added. Portland General says a heat pump's load may cause the voltage to drop too low and asks customers to call so it can check the service. CPS Energy advises having a licensed electrician check the circuits when lights flicker as a large load such as an air conditioner kicks on.
• Lights that stay dim. FPL says to turn off major appliances and call it.
• Dimming on one circuit. PG&E says the circuit feeding the refrigerator may be overloaded or have an internal wiring deficiency, that most electric codes now require large switching loads to have their own circuit, and that owners of older homes may want an electrician to check.

When the Whole House Flickers

1. Check the neighbors and the weather. FPL tells apartment residents to check whether neighbors are affected and, if so, to call the utility. Con Edison says heat waves can overload its equipment, causing dim or flickering lights.
2. Know your utility's rule for one blink. Portland General says there's no need to call about a blink, and Shenandoah Valley Electric Cooperative says sporadic blinks probably aren't worth reporting but regular ones are. Con Edison asks for a report of dim or flickering lights right away.
3. Call the utility for repeated flicker, dimming, or flicker in the wind. PG&E sends a troubleman for flickering lights and, if it finds nothing, may leave a recording volt meter for a few days. MidAmerican Energy says it will make repairs or advise you to hire a licensed electrician, depending on where the problem is. For flicker in the wind, the CPSC says not to touch any of the equipment and to call the power company immediately. FPL says not to touch the meter, and the cooperative doesn't work past the meter base, so problems on your side of it are an electrician's.
4. Protect the electronics. Portland General says storms that make lights flicker can bring surges; without surge protection, unplug sensitive equipment such as TVs and computers.
5. If some lights are brighter than normal, follow the urgent steps in our partial power guide.

What You Can Fix Yourself

• Snug or replace the bulb with the light switched off, using one that matches the fixture's marked wattage, as the U.S. Fire Administration advises.
• Read the package. ENERGY STAR says every dimmable ENERGY STAR LED bulb has the word "dimmable" on the front, and Leviton says to pair dimmable bulbs with a dimmer rated for LEDs; older models may not be.
• Adjust the dimmer's low end. Leviton says a low-end trim or minimum-level setting can help with flicker at low light levels, and suggests checking the dimmer's instruction sheet for one; Lutron's Caséta instructions point owners whose dimmable LEDs flicker or turn off to the same adjustment.
• Match or change the bulbs. Leviton strongly recommends one light source per dimmer, since mixing bulb types can vary dimming. Not every bulb works well with every dimmer, ENERGY STAR says, so try a different bulb or change the switch; Lutron, Leviton, and Feit publish compatibility lists or tools.
• Map your circuits: switch off one breaker at a time and label what goes dark. The ESFi says a circuit map tells you which circuit to shut off in an electrical emergency.

Swapping a dimmer is switch work. Our DIY vs. hire-a-pro guide puts replacing a switch with an identical one in its careful-DIY tier: breaker off, test it dead, photograph the wiring. A different type of dimmer isn't identical, and Leviton notes electronic low-voltage dimmers need a neutral wire, often missing in older construction; that's an electrician's job.

When to Call a Pro

Call a licensed electrician now, and leave the circuit off, for:

• A hot or discolored switch plate or outlet. The CPSC says to stop using a hot outlet or switch immediately and get a qualified electrician as soon as possible. A dimmer may run warm normally, the CPSC notes, but the ESFi says hot is not okay.
• A burning smell, buzzing, or sparks. The CPSC says overheated wires often give off an odor of hot insulation, and a switch that sparks when you use it needs a qualified electrician.
• A shock or tingle from a switch plate or outlet. The CPSC says to turn off that circuit at the panel unless it feeds an essential appliance, and not to touch it until an electrician helps.

Call the electric utility for flicker in the wind or sparking at the wires to the house (CPSC), lights that stay dim (FPL), a big dip every time a heat pump starts (Portland General), or repeated whole-house flicker (MidAmerican, PG&E).

Book an electrician soon for flicker confined to one room or circuit, a switch that doesn't work right, flicker whenever the air conditioner starts (CPS Energy), or aluminum or knob-and-tube wiring. The ESFi suggests an inspection if lights often flicker or dim momentarily.

Prevent It

• Feel switch plates and outlets now and then, as the CPSC advises if you know you have push-in backwire connections.
• Keep big appliances on their own circuits; PG&E says not to let them share with sensitive electronics.
• Get an inspection if the house is 40 or more years old, you're its new owner, or a major appliance such as an air conditioner was added in the last 10 years, as the ESFi suggests. The U.S. Fire Administration notes older wiring may not have the capacity to safely handle newer appliances.
• Use surge protectors for electronics, as MidAmerican Energy recommends.

Frequently Asked Questions

Are flickering lights dangerous?

One flickering LED bulb rarely is, Signify says. Flicker across a room or circuit can be, because the CPSC ties loose connections to arcing, overheating, and fire.

Why are my LED lights flickering?

On a dimmer, usually a mismatch: a dimmer not rated for LEDs, a non-dimmable bulb, or too little load (Feit). Without one, check that the bulb is tight; GE Lighting says refrigerators and dryers can put noise on the line that makes LEDs flicker, and LEDVANCE says lower-quality LED bulbs flicker more readily.

Why do my lights flicker when the AC turns on?

A compressor's high start-up current can pull the voltage down briefly, Goodman notes. If the dip is noticeable every time, or started with a new AC or heat pump, call the utility to check your service, as Portland General suggests, and have an electrician check the circuits, as CPS Energy advises.

Why are all the lights in my house flickering?

Check the neighbors. Portland General says a single blink generally means a fault nearby that its equipment cleared. Repeated flicker, dimming, or flicker in the wind needs a call to the utility, and our partial power guide treats lights brighter in some rooms as urgent.

The Bottom Line

One bulb: tighten it, replace it, or match it to the dimmer. One room or circuit: assume a loose connection and call an electrician. A big dip every time the AC starts: the utility, then an electrician. The whole house flickering: the utility. Heat, a burning smell, buzzing, or sparks: leave the circuit off and call an electrician now.

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