Why are my lights flickering? Causes and when it’s dangerous

Flickering lights can have simple causes, such as a bulb and dimmer that do not suit each other, or more serious ones, such as a loose connection in a fitting or in the wiring. If the whole house or street flickers, the cause may be the electricity network. Crackling, buzzing or a burning smell is an emergency.

Is it one light, one room or the whole house?

This is the most useful thing to work out, because it points to where the problem is.

• One light: the cause is usually the bulb, the fitting it sits in, or a dimmer or switch that controls it.
• One room or area: the cause may be a shared circuit or a connection somewhere along it.
• The whole house: the cause may be inside the home’s main wiring or connection to the street.
• Neighbours too: the cause is more likely to be on the network, not in your home.

You can work this out by watching and noting, without touching anything. If neighbours are affected as well, report it to your network provider’s faults line.

Why do mismatched bulbs and dimmers cause flicker?

Many LED lamps behave differently from the older bulbs they replaced. A dimmer made for old-style bulbs may not control an LED smoothly, which can cause flicker or buzzing. The same can happen when LED lamps are used with an older transformer. This is explained more in our article on LED downlights.

Changing a dimmer, transformer or fitting is electrical work, and in Queensland it must be done by a licensed electrician. Do not try to fix it yourself, even if the problem looks small.

What can cause flicker inside the home?

In general terms, the common causes are:

• a lamp that does not suit the dimmer, transformer or fitting
• a worn or loose connection inside a light fitting, switch or power point
• a loose connection along the circuit wiring
• a large appliance starting up on the same circuit, which can briefly pull voltage down
• an issue with the main connection to the street

Only a licensed electrician can find which of these it is. Finding it involves testing and opening up wiring, which should never be done by a householder.

When is flickering dangerous?

Occasional, brief flicker that affects one light and has no sound, heat or smell is usually less urgent, but it should still be looked at if it keeps happening. Flicker that is getting worse, spreads to other lights, comes with other signs or happens along with a breaker or safety switch tripping should be checked promptly.