Introduction

Many people never noticed flicker until they switched to LED bulbs. The old bulbs hid it. The new ones show every small dip in voltage, and suddenly lights flicker when appliance turns on in rooms that seemed fine for years.

Before you blame the wiring, it helps to separate bulb problems from circuit problems. This guide shows how to tell them apart with a few simple tests.

Why LEDs Show Flicker That Old Bulbs Hid

An incandescent bulb makes light by heating a filament. That filament stays hot for a split second after voltage drops, so a brief dip barely changes the glow.

An LED has no filament. Inside each bulb is a small circuit called a driver, which converts household AC power into the low-voltage DC the diodes need. When voltage dips, the driver reacts almost instantly, and you see a blink.

The same dip that was invisible in 2005 can be obvious today. That does not mean your house got worse.…