Why Your Lights Dim When the AC Kicks On

Here's the short version: an air conditioner pulls a big gulp of power the instant its compressor starts. For a fraction of a second, that inrush current drags down the voltage across your home — and your lights dip with it.

A tiny, brief flicker once in a while is usually normal. It's physics, not a fault.

The flicker becomes a warning sign when it's dramatic, when it happens on every appliance startup, or when lights visibly dim for a full second or more. That often points to an overloaded circuit, a loose connection, an undersized panel, or aging service that can't comfortably handle modern loads.

In older Phoenix homes running a modern AC — plus a pool pump, an EV charger, and everything else — the panel is frequently the bottleneck. A quick safety inspection pinpoints exactly where.