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lights flicker when the aircon kicks in, is that bad

The question, put plainly: Why do my lights flicker or dim when an appliance starts?

The short answer

A brief dip when a large motor starts can be normal, but persistent flickering, or flickering that has recently started, commonly indicates a loose connection and should be investigated rather than lived with.

TradieAnswers editorial · written in-house and sourced to the authorities listed below

Checked against 4 published sources, listed in full at the end of this page. How we source this

Motors draw a large surge at the instant they start. An air conditioner compressor, a pool pump or a workshop saw can briefly pull several times its running current, and a small, momentary dip in the lights at that instant is ordinary physics rather than a fault.

When it is not normal

  • Flickering that persists rather than lasting a fraction of a second.
  • Flickering across several rooms at once, which points upstream of any one circuit.
  • A change from how the house used to behave, with no new appliance to explain it.
  • Flickering accompanied by any smell of hot plastic, warm switch plates or a buzzing sound at the board.

Why a loose connection is urgent

A loose termination has resistance. Resistance under load makes heat. Heat degrades the connection further, which raises the resistance, which makes more heat. That feedback loop is a well understood cause of switchboard and outlet fires, and it announces itself first as flickering and warmth. This is the class of fault worth calling about rather than watching.

Sources

Every source below was fetched and its response recorded on the date shown. Where a government site blocks automated clients, that is noted rather than reported as a successful check.

  1. Electricians · NSW GovernmentChecked 2026-08-10 · responded 200 OK
  2. Search a public register · Energy Safe VictoriaChecked 2026-08-10 · responded 200 OK
  3. Electrical safety laws · WorkSafe QueenslandChecked 2026-08-10 · live, but blocks automated clients so the specific page could not be confirmed
  4. Standards Australia · Standards AustraliaChecked 2026-08-10 · responded 200 OK

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