Why Are My Lights Flickering? What It Means and When to Call an Electrician
Are you experiencing issues with your home or business's electricity?
Our licensed electricians at Sydney Electrical Service are waiting to assist you.
Call Us 0433 462 902 Send your Online Enquiry- Cause #1: Loose or Poorly Seated Light Bulb
- Cause #2: Incompatible or Faulty Dimmer Switch
- Cause #3: Overloaded Circuit
- Cause #4: Loose Wiring Connection
- Cause #5: Failing Light Fitting or Ballast
- Cause #6: Voltage Fluctuation from the Supply
- Cause #7: Ageing Switchboard or Deteriorating Wiring
Lights flickering in your home can range from a minor nuisance — a bulb that needs reseating — to an early sign of a wiring fault that carries a real fire and shock risk. SafeWork NSW advises homeowners to treat unexplained electrical faults as hazardous until a licensed electrician has investigated. This guide covers seven common causes, what you can safely check yourself, and when it is time to call a professional — ranked from least to most serious.
Seven Common Causes of Flickering Lights
The pattern of the flickering matters: one fitting, one circuit, or the whole house each point in different directions. Work through the causes below in order before assuming the worst — but do not delay if you smell burning or see scorch marks.
Cause #1: Loose or Poorly Seated Light Bulb
A bulb that is not fully screwed into its socket creates an intermittent contact that makes the light flicker, especially with vibration or when the fitting warms up. This is the most common and most benign cause — always rule it out first.
What you can safely do: Switch off the light at the wall and wait a minute for the globe to cool. Check that the bulb is firmly seated in the fitting. If it was loose, tighten it and test again. If flickering continues with a correctly seated bulb, the fitting or the wiring behind it needs a closer look by a licensed electrician.
Cause #2: Incompatible or Faulty Dimmer Switch
Many older dimmer switches were designed for incandescent globes and are not compatible with LED bulbs. Running an LED on a mismatched dimmer — particularly at low brightness settings — produces a rapid cycling effect that ranges from a subtle shimmer to a pronounced strobe-like flicker.
If the problem is specific to lights on a dimmer and disappears at full brightness, incompatibility is likely. The fix is an LED-compatible dimmer switch, which a licensed electrician can swap in quickly.
What you can safely do: Note whether the flickering is tied to dimmer-controlled circuits. Check that the globe itself is labelled "dimmable" — many standard LEDs are not. Beyond that, replacement is a job for a licensed electrician.
Cause #3: Overloaded Circuit
When a high-draw appliance — an air conditioner, washing machine, or electric oven — starts up, it briefly draws far more current than it needs at steady state. That inrush current causes a momentary voltage drop on the circuit, making lights flicker for a second or two before settling.
Occasional flickering when a large appliance kicks in is common. But if lights dim noticeably or flicker frequently, the circuit may be carrying more load than it is rated for — a situation that can also lead to a circuit breaker that keeps tripping.
What you can safely do: Note when the flickering happens. If it consistently coincides with the fridge compressor cycling on or the washing machine starting, you have a useful clue. Spread high-draw appliances across different circuits where you can. If the problem persists, a licensed electrician can assess the circuit load.
Cause #4: Loose Wiring Connection
A loose terminal at a light switch, power point, or junction box creates an intermittent contact that generates heat and can cause arcing. Arcing is a leading cause of electrical fires — and because the visible symptom is just a flickering light, it often goes unaddressed for months.
Loose connections develop from vibration over time, from wiring that was not correctly terminated at installation, or from aluminium wiring — common in Sydney homes built in the 1960s and 70s — which expands and contracts differently to copper and works connections loose over years of use.
What you can safely do: Nothing. Do not open the switch plate, the power point, or the switchboard. Treat persistent flickering in a single fitting or switch as a possible loose connection until an electrician rules it out.
For urgent situations — a burning smell, warmth around a switch or outlet, or scorch marks near a fitting — our emergency electricians are available across Sydney 24 hours a day, arriving in 30–90 minutes. Call 0433 462 902.
Cause #5: Failing Light Fitting or Ballast
Fluorescent tubes flicker when the tube is near end of life or when the ballast — the component that regulates power to the tube — starts to fail. The flicker often has a slow, visible pulse and worsens as the fitting warms up.
Some integrated LED downlights display similar behaviour when the driver circuit inside the fitting begins to degrade, particularly in fittings that run hot or that are more than a decade old.
What you can safely do: For a fluorescent fitting, try replacing the tube. If the flicker persists with a new tube, the ballast has failed and the fitting needs to be replaced by a licensed electrician. Do not attempt to open fittings or access internal components yourself.
Cause #6: Voltage Fluctuation from the Supply
If lights flicker across multiple rooms or throughout the whole house — particularly when no single appliance is starting up — the cause may be with the incoming power supply rather than your internal wiring. Supply voltage in NSW is nominally 230 V; significant deviations from that cause visible brightness variation.
Whole-house voltage fluctuations can stem from a problem with the consumer mains connection at the point of attachment — where the network cables connect to your property — or from a fault further back in the distribution network. They can also accompany power surge damage that has stressed wiring or appliances throughout the home.
What you can safely do: Check whether your neighbours are experiencing the same issue. If they are, the problem is likely in the network — contact Ausgrid or Endeavour Energy (depending on your area) to report it. If the issue is isolated to your property, call a licensed electrician who can measure supply voltage and inspect the consumer mains connection.
Cause #7: Ageing Switchboard or Deteriorating Wiring
In older Sydney homes — particularly those built before the 1980s — wiring insulation degrades with age and repeated heat cycles. Degraded insulation increases resistance, and that increased resistance causes voltage drops and flickering that can be intermittent and difficult to trace without professional testing.
An ageing switchboard compounds the risk. Older boards without RCDs (safety switches) offer little protection against the earth leakage faults that often accompany deteriorating wiring. If your home has an older board with ceramic fuses or no safety switches, a switchboard upgrade is worth discussing with your electrician. For a detailed look at the diagnostic steps involved, our lights flickering fault guide covers what a licensed electrician checks on site.
What you can safely do: Nothing. Deteriorating wiring is not a DIY diagnosis. A licensed electrician can run an insulation resistance test to assess the condition of your wiring and advise on the appropriate next step.
FAQs
Why are my lights flickering?
Lights flicker when there is an inconsistent supply of electricity to the fitting — caused by anything from a loose bulb to a failing ballast, an overloaded circuit, a loose wiring connection, or a supply voltage issue. The pattern helps narrow it down: one fitting suggests a local problem; one circuit points to wiring or load; whole-house flickering suggests a supply or switchboard issue.
Is flickering lights a serious problem?
It depends on the cause. A loose bulb or an incompatible dimmer is low risk and easy to fix. Loose wiring connections that cause arcing are serious — they are a known cause of electrical fires. Any flickering accompanied by a burning smell, warmth around a switch, or scorch marks should be treated as urgent and investigated by a licensed electrician promptly.
Can I fix flickering lights myself?
You can safely reseat a light globe, replace a fluorescent tube, or note whether the flickering is linked to a dimmer switch or a particular appliance starting up. Beyond those checks, flickering that persists or recurs should be assessed by a licensed electrician. Opening switch plates, power points, or the switchboard without the correct licence is illegal in NSW.
Why do my lights flicker when the air conditioner turns on?
Brief flickering when a large appliance starts is caused by inrush current — the high startup draw of the motor temporarily drops voltage on the circuit. Flickering that lasts less than a second is common. If it is prolonged or the lights dim noticeably, the circuit may be overloaded or there may be a loose connection amplifying the voltage drop. A licensed electrician can assess the circuit load and wiring.
Why do my lights flicker at night but not during the day?
Nighttime flickering that stops during the day often points to appliances with compressors or thermostats that cycle on when temperatures drop — fridges, freezers, or ducted air conditioning units. It can also indicate a loose connection that is temperature-sensitive, or a failing ballast that behaves differently once it cools down.
Do flickering lights mean I need a switchboard upgrade?
Not necessarily — but if flickering is widespread and your home has an older switchboard with no safety switches or still uses ceramic fuses, a switchboard upgrade is worth discussing with a licensed electrician. Modern switchboards include RCD protection on all circuits, which significantly reduces the risk from the wiring faults that often cause flickering in older homes.
How do I know if flickering lights are a fire risk?
Treat flickering lights as a potential fire risk if you notice a burning smell, a switch or power point that feels warm to touch, scorch marks near a fitting, a light that flickers and then goes out entirely, or a problem that appeared suddenly with no obvious cause. In any of these situations, switch the light off at the wall and call a licensed electrician without delay.
Keeping Your Home Safe from Flickering Light Faults with Sydney Electrical Service
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