You switch on the air conditioner and the lights briefly dim. The refrigerator starts humming and the kitchen lights flicker. Perhaps the kettle, microwave or clothes dryer causes lights elsewhere in the house to change brightness.
It is easy to assume the lights are faulty, particularly when the home has LED downlights. However, the light may simply be where you can see an electrical problem occurring somewhere else.
The important question is not only: Why is my light flickering?
It is: Why does turning on one appliance affect the lights in another part of the house?
The answer can range from an ageing LED driver to a loose connection, an appliance fault, excessive voltage drop or a problem with the electricity supply entering the property.
The Light May Be the Messenger, Not the Problem
Lighting makes changes in voltage easy to notice. A television, refrigerator or air conditioner may continue operating through a small voltage fluctuation, while an LED light responds immediately by becoming brighter, duller or visibly flickering.
This means replacing the globe or downlight will not necessarily solve the problem.
If one light flickers independently, the fault may be within that fitting. If several lights react whenever a different appliance operates, the cause could be elsewhere in the electrical system.
Why Do Lights Dip When an Air Conditioner or Fridge Starts?
Appliances containing motors or compressors can require a large amount of current for a brief period while starting.
This includes:
- Split-system air conditioners
- Refrigerators and freezers
- Pool pumps
- Water pumps
- Clothes dryers
- Workshop machinery
- Some older exhaust fans and ceiling fans
Once the motor is running, its current demand usually falls. That is why the light may dip for only a fraction of a second as the compressor or motor starts.
A very slight, momentary change may not automatically mean the property is unsafe. However, the dip should not be severe, prolonged, accompanied by other symptoms or progressively becoming worse.
What If the Kettle or Heater Causes the Lights to Dim?
A kettle, portable heater or electric oven works differently from an air conditioner compressor. It does not normally create the same motor-starting surge, but it can still place a significant load on the electrical system while operating.
If switching on a high-powered appliance causes noticeable dimming throughout the home, it may expose:
- Excessive voltage drop
- A poor or loose electrical connection
- A circuit carrying more load than expected
- An issue with the consumer mains
- A problem with the incoming electricity supply
The appliance has not necessarily caused the underlying problem. Its electrical demand may simply make an existing weakness more visible.
Flickering, Dimming and Brightening Are Not the Same Symptom
Homeowners often describe every change in lighting as “flickering”, but the exact behaviour matters when an electrician begins fault-finding.
| What the lights are doing | What the pattern may indicate |
|---|---|
| One light flickers by itself | A globe, LED driver, dimmer, fitting or local connection may require inspection. |
| Several lights on one circuit flicker | The issue may involve that lighting circuit, a connection or equipment connected to it. |
| Lights dip when one appliance starts | The appliance’s starting demand, the circuit supplying it or voltage drop may need investigation. |
| Lights throughout the house flicker together | The problem may be closer to the switchboard, consumer mains, service connection or network supply. |
| Some lights become brighter while others become duller | This can indicate unstable voltage and requires prompt professional attention. |
| Lights remain dim while an appliance operates | This may indicate a sustained voltage problem rather than a brief starting event. |
| Lights flicker and appliances reset | The voltage disturbance may be affecting the wider electrical installation or incoming supply. |
These patterns are useful observations, but they are not a safe way for a homeowner to diagnose the fault themselves. Electrical testing should be completed by a licensed electrician or the electricity distributor, depending on where the problem is located.
Why Lights Becoming Brighter Can Be More Concerning
A brief voltage drop usually causes a light to become duller.
If some lights become unusually bright while others become dim, the voltage may not be distributing normally throughout the home. This can occur with certain connection or neutral faults.
It may also affect appliances and electronic equipment that were designed to operate within a particular voltage range.
Do not ignore lights that repeatedly surge in brightness, particularly when the behaviour affects multiple rooms or is accompanied by:
- Appliances restarting
- Televisions switching off
- Internet routers rebooting
- Unusual buzzing
- A burning smell
- Partial loss of power
- Shocks or tingles from taps, appliances or metal surfaces
Common Causes of Lights Flickering or Dimming
1. A Faulty Globe or LED Driver
If only one light is affected, the cause may be relatively local. LED fittings contain electronic components that can fail, particularly as they age or experience heat inside the ceiling.
A failing LED driver can cause:
- Intermittent flickering
- Delayed start-up
- Changes in brightness
- A light switching off after warming up
- A fitting that works unpredictably
2. An Incompatible or Failing Dimmer
Not every LED fitting works correctly with every dimmer. An incompatible combination may flicker at lower settings, pulse after being switched on or fail to dim smoothly.
This usually affects the lights controlled by that dimmer rather than unrelated rooms throughout the house.
3. A Loose Electrical Connection
A loose connection can create intermittent electrical behaviour as loads switch on and off.
The connection could be located at a fitting, switch, junction, circuit protection device, switchboard or another part of the installation. Because loose connections may generate heat, repeated or worsening flickering should not be treated as a harmless inconvenience.
4. Excessive Voltage Drop
Voltage naturally changes as electrical current moves through cables and connections. The electrical installation should be designed so that this remains within acceptable limits.
Noticeable voltage drop may become more apparent when:
- A high-powered appliance operates
- A cable run is particularly long
- A circuit supplies several loads
- A connection has deteriorated
- An appliance draws more current than expected
5. A Faulty Appliance
The appliance that triggers the dimming may itself require attention.
A compressor, motor or internal electrical component may be struggling to start or drawing an abnormal amount of current. This does not always trip a circuit breaker immediately.
An electrician can test whether the symptom follows the appliance, the circuit or the wider property supply.
6. A Problem at the Switchboard or Consumer Mains
If unrelated circuits are affected simultaneously, the fault may be located upstream from the individual lighting circuit.
This could include connections at the switchboard, the consumer mains or equipment associated with the property’s incoming supply.
This is one reason whole-home flickering should not be approached by repeatedly replacing downlights.
7. An Electricity Network Supply Problem
Not every voltage problem originates inside the home.
The fault may involve the service connection or the local electricity network. Neighbours experiencing similar symptoms at the same time can be an important clue, but homeowners should not wait for confirmation from nearby properties before reporting serious inconsistent power.
Questions an Electrician May Ask
You should not remove fittings, open the switchboard or perform electrical testing yourself. However, safely observing the pattern can help an electrician narrow down the problem.
Useful details include:
- Which appliance was turned on when the lights changed?
- Does it happen every time or only occasionally?
- Is one light affected, one room or the entire house?
- Do the lights become duller, brighter or both?
- Does the change last for a fraction of a second or continue?
- Do televisions, computers or internet equipment restart?
- Has the problem recently become more frequent?
- Is there any buzzing, crackling, heat or burning smell?
- Are neighbouring homes experiencing similar issues?
A short video of the symptom may also be useful if it can be recorded without approaching or touching electrical equipment.
When Should You Call an Electrician?
Arrange an electrical inspection when:
- One fitting or lighting circuit repeatedly flickers
- An appliance consistently causes the lights to dip
- The problem is becoming more frequent or severe
- A switch, fitting or power point is buzzing
- A fitting smells hot or appears discoloured
- A circuit breaker or safety switch is also tripping
- You suspect an appliance or internal circuit is faulty
- You are unsure whether the issue is inside the property
A licensed electrician can test the voltage, inspect accessible connections, assess the relevant circuits and determine whether the problem appears to be within the property or should be escalated to the electricity distributor.
When Should You Contact Energex?
Dull or flickering lights throughout the home, a brownout, low voltage or power reaching only part of the property can indicate inconsistent electricity supply.
Energex advises residents experiencing inconsistent power not to touch the switchboard or metal objects in the home. Where power points can be accessed safely and easily, appliances can be switched off and unplugged before calling Energex immediately on 13 19 62.
Shocks or tingles from appliances, taps or other metal surfaces must also be treated seriously. Do not continue touching the object to see whether the sensation happens again.
Do Not Keep Resetting the Switchboard
A circuit breaker or safety switch that trips is responding to an electrical condition. Continually resetting it without knowing why can repeatedly energise faulty equipment or wiring.
Likewise, do not remove the switchboard cover, tighten electrical connections, swap fixed wiring or attempt to measure the incoming supply yourself.
The safer approach is to leave electrical fault-finding to a licensed electrician and follow Energex’s instructions when the symptoms indicate an inconsistent network supply.
Do Not Ignore a Pattern That Is Getting Worse
A single failed LED fitting is different from every light in the home changing brightness when an appliance starts.
The location, timing and severity of the symptom help determine whether the likely cause is:
- The light itself
- The lighting circuit
- Another appliance
- A connection within the home
- The switchboard or consumer mains
- The incoming electricity supply
The light may be where you notice the problem, but it is not necessarily where the fault is located.
Power Bolt Electrical provides residential electrical fault-finding throughout Narangba, North Lakes, Moreton Bay and surrounding North Brisbane suburbs.
If your lights repeatedly flicker, dim or become brighter when appliances operate, contact Power Bolt Electrical to arrange an inspection.
Frequently Asked Questions
Is it normal for lights to dim when the air conditioner turns on?
A very slight, split-second dip can occur when an air conditioner compressor starts. However, severe dimming, prolonged dimming, repeated flickering or appliances resetting at the same time should be investigated.
Why do my lights flicker when the fridge starts?
A refrigerator compressor draws additional current while starting. If the resulting light flicker is noticeable, worsening or affecting several parts of the home, an electrician may need to inspect the appliance, circuit, connections and supply voltage.
Why do my lights dim when I use the kettle?
Kettles draw considerable power while heating. Noticeable dimming may expose excessive voltage drop, a poor connection or an issue with the incoming supply. The cause cannot be confirmed safely without electrical testing.
Can a faulty appliance cause lights to flicker?
Yes. A motor, compressor or internal component that is struggling to start may draw abnormal current and cause a visible change in nearby lighting. An electrician can determine whether the problem follows the appliance, its circuit or the wider electrical installation.
Why are some lights getting brighter while others become dimmer?
This can indicate unstable voltage or a connection problem and should be treated more seriously than one isolated flickering light. Contact a licensed electrician or Energex promptly, depending on whether the problem appears isolated or affects the whole property.
Should I reset the switchboard when my lights flicker?
Do not repeatedly reset circuit breakers or safety switches without knowing why they operated. If the whole home has dull or flickering lights, low voltage or partial power, do not touch the switchboard and contact Energex immediately.
When should I call Energex about flickering lights?
Contact Energex when flickering affects the wider home or is accompanied by a brownout, low voltage, partial supply, shocks or tingles. Energex's emergency and inconsistent-supply number is 13 19 62.