The tube light that flickers: starter, tube, driver or switch - five minutes to know

A flickering ceiling light runs through the same four suspects in every flat, and the honest part is that three of the four are a screwdriver-free, market-money fix. Work the ladder cheapest-first; it ends the argument faster than any electrician visit and teaches you which part of the fitting is tired.

The swap ladder

1. First, rule out the dumb ones. Does the flicker happen in more than one fitting at once, especially when the generator or inverter swaps over? That is supply-side, not lamp-side - the driver chapters cover the why; a bulb seated loose in a hot holder is also "dumb" and it's ten seconds: switch off at the wall, let it cool, finger-tight.
2. Flicker + a tube with grey-black ends: the tube is at end of life - replace the tube. If the ends darken again fast, the real failure is the tube's heater circuit in the ballast; bench later.
3. Flicker on a starter-fitted fluorescent fitting (the old ones with a small twist-out can under the tube cover): that can is the starter, and a starter costs what a bread loaf costs, so replace it first - a failing starter flickers for months while the tube stays perfect, which is why "new tube didn't fix it" is this fixture's catchphrase.
4. An electronic fitting or LED panel: the driver - the little box or the internals behind the panel - is the part that ages, and the symptom of a dying LED driver is flicker and slow-start, not total death. The repair is a matched driver (same output watts and current range, the label tells you both) or the whole panel, which is the cheaper labour either way.

The dimmer trap, and the buzz that ends DIY

A "good" bulb flickering or buzzing on an old wall control is a compatibility story, not a quality one: leading-edge dimmers were built for filaments and coils, and an LED's electronics don't like them - dimming a non-dimmable lamp is the same argument, guaranteed; there is a dimmer-compatible line on the box, and pairing it with a trailing-edge control is the whole fix - one of these two lines, and the flicker leaves both the fitting and the argument. Now the stop signs, no ladder past them: a buzz from the fitting itself (mains-frequency hum from a tired ballast or a loose driver) means vibration at line voltage, and a ballast that hums is a ballast that goes; flicker plus a warm smell or a discoloured plate/switch plate is the burning-smell chapter's opening line, which says power off and call the licensed person; and any job that opens the fitting's live terminals is, in this site's standing rule, an electrician's job in a house with a meter and a changeover - what was covered here is the user-serviceable skin of the problem, and the ladder's bottom rung ("new driver, still flickers - the neutral is loose upstream") is the point where the desk says hands off, meter on, professional.

The upgrade that ends the flicker permanently, with one caveat

Replacing a flickering fluorescent fitting wholesale with a quality LED panel is the market-money fix that never needs a starter again - with one caveat that saves the purchase: the old fitting's earth and the new panel's driver need a proper box and a licensed pair of hands in most homes' wiring, and a bulb that flickers in every socket you test it in was never the bulb's story at all.