When lights flicker, the cause is one of four things, and they range from buy-a-better-bulb to call-someone-this-week. Here is how to tell which one you have, starting with the one that matters.
The one that matters: a loose connection
Lights that flicker on their own, with no pattern, especially on one circuit or in one part of the house, usually mean a connection working loose somewhere: at a device, in a junction box, at the panel, or at the service entrance. A loose connection arcs, arcing makes heat, and heat at a connection is the mechanism behind most electrical fires.
The tells: flicker limited to one circuit, flicker that gets worse over weeks, any buzzing, or a warm switch or outlet nearby. That combination is a repair call, not a bulb run. In houses from the aluminum era, roughly 1965 to 1978, take it more seriously again, because loosening connections are exactly aluminum wiring’s failure mode.
The whole-house version
If everything dims together when the heat pump, dryer or well pump starts, your service is being asked for a big gulp and sagging while it pours. Brief and mild is common in older 100 amp services. Frequent and deep means the service is undersized for the house it now runs, which is a panel conversation, or that the connection at the utility side is failing, which is worth reporting.
The harmless two
LED bulbs on the wrong dimmer flicker at low settings because the dimmer was made for incandescents. The fix is an LED-rated dimmer, ten minutes.
One bulb, one fixture is nearly always the bulb or its socket contact. Swap the bulb before diagnosing anything.
The five-minute triage
One bulb: swap it. One dimmer: check its rating. One circuit, random flicker: book us. Whole house, when something big starts: tell us how often, and if lights flicker along with any burning smell or a hot device face, treat it as an emergency tonight, not a repair next week.