Why do my lights flicker?

Most flickering comes from one of four places: the bulb or dimmer, a loose connection at a fixture, switch or outlet, a big appliance starting up, or the utility's connection to your house. Which one depends on how widespread it is and when it happens. The CPSC lists dim or flickering lights, where lights dim or the size of the television picture shrinks often, among its warnings of potential hazards in a home's electrical system.^[1]

You can sort out the likely cause by observation alone, and that is worth doing before you call anyone. Anything beyond swapping a bulb is licensed electrician work.

Start with the pattern

The pattern points to the cause better than any test you could run yourself.

• One light. The bulb, its socket, or the fixture's connections. A worn bulb or an LED bulb that does not suit its dimmer is the cheapest cause.
• Several lights on one switch or circuit. A shared connection, such as a switch, a splice in a box or a loose wire at an outlet that feeds the others.
• Lights dip when a large appliance starts. The appliance is pulling a surge of current as its motor starts.
• Lights all over the house, or only in wind. The problem is probably at the panel or where the utility's wires meet the house.
• Flickering that comes with a hot cover plate, a buzzing sound or a burning smell. Treat it as urgent and read when flickering lights are an electrical emergency.

Bulbs and dimmers

A bulb that is not seated firmly, a worn bulb, or an LED on an old dimmer built for incandescent bulbs can all flicker without any wiring fault. The cheap test is whether the flicker follows the bulb to another fixture or stays with the original one. Some dimmer switches may warm during normal use,^[2] so a slightly warm dimmer is not by itself a sign of trouble, but one that is hot or buzzing is.

A loose connection

When the bulb is not the cause, a loose connection is the cause electricians worry about most, because it can arc and heat up. The CPSC says improperly operating outlets or switches may indicate an unsafe wiring condition, and that a loose screw holding a wire or a worn out switch can lead to electrical arcing, overheating, or a fire.^[2]

That is why a flicker that moves when you touch a switch or jiggle a fixture should be treated as a repair, not a quirk. Finding the loose point means opening boxes and testing live circuits, which is not homeowner work. What an electrician checks, and in what order, is in what an electrician looks for when lights flicker.

A large appliance starting

If the lights dim for a moment when the air conditioner, heat pump, well pump or dryer starts, that is often just the motor's starting surge. Dominion Energy's electric service requirements say motors with more than 30 amps per ton of starting current, such as those in larger residential heat pumps or air conditioners, may create excessive voltage flicker,^[3] and it recommends a manufacturer's hard-start kit to minimize how long the flicker lasts.^[3]

A brief dip at start-up that has always been there is different from one that is new, longer or getting worse. A change suggests the appliance, or a connection on its circuit, needs a technician.

Wind, rain or the whole house

If the entire house flickers, or it happens when the wind blows, the cause may be outside. The CPSC says flickering of home lights when the wind blows can be caused by bad contacts at the junction of the service entrance cable and the service drop.^[1] That junction is at the point where the utility's overhead wires meet your house.

This is not something to investigate yourself. The CPSC says not to attempt to correct the problem yourself or touch any of the equipment, and to call the electric power company immediately.^[1] Stay away from any wires that are sparking or hanging low and report them to the utility.

What to note before you call

Write down which lights flicker, whether it happens at certain times or with certain appliances, how long it has been going on, and whether anything is warm, buzzing or smells of burning. A clear description shortens the visit, and it is the cheapest part of the job to get right. For what the visit costs, see how much an electrician charges to fix flickering lights in Virginia.

When to call a licensed pro

For any flicker that is not cured by a new bulb. Virginia law says no individual shall engage in, or offer to engage in, work as a tradesman unless licensed under the article that governs tradesmen,^[4] so ask to see an electrician's licence. Check the licence before anyone opens a panel or a box: how to check if a contractor is licensed in Virginia shows how.

Call the electric company instead if the whole house is affected, if it happens in wind, or if you see sparks outside near the wires or the meter. Loclis lists licensed electrical businesses; browse electrical services or read more electrical repair answers.

To get the cause found and fixed, describe the problem once and licensed local electricians quote the visit.