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uk Home & property emergencies lights dim when appliance starts • lights dimming suddenly • lights flicker when kettle on • lights flicker when shower on • voltage drop at home • possible electrical fault • suspected loose wiring • overloaded circuit signs • consumer unit tripping • dim lights across multiple rooms • buzzing from socket • burning smell electrics • hot outlet or switch • power dip in house • uk power supply fluctuation • dno report voltage problem • appliance causes lights to dim • electrician urgent call

What to do if…
your lights dim noticeably when appliances start and you suspect an electrical fault

Short answer

Stop using the appliance(s) that trigger the dimming, and treat it as a potential electrical safety issue until checked. If you also notice heat, burning smells, buzzing/crackling, sparks, or repeated trips, switch off power at the consumer unit and get urgent professional help.

Do not do these things

  • Don’t keep “testing” by turning the appliance on and off repeatedly.
  • Don’t ignore burning smells, buzzing/crackling, scorch marks, or warm switches/sockets.
  • Don’t open the consumer unit cover or attempt DIY wiring repairs.
  • Don’t keep using multiway adapters/extension leads to “work around” the issue.
  • Don’t touch a socket/switch that feels hot—switch off power to that circuit first (or the main switch if unsure).

What to do now

  1. Make a safe pause. Turn off and unplug the appliance that makes the lights dim (if it’s safe to do so). If it’s hard-wired (e.g., some showers/ovens), turn it off at its isolator switch and leave it off.
  2. Scan for danger signs (30 seconds). Look/smell/listen for: burning/plastic smell, buzzing/crackling at sockets/switches, visible sparking, scorch marks, or anything unusually warm.
  3. If any danger sign is present:
    • Switch off power at the consumer unit (main switch), if safe.
    • Move people/pets away from the area; if there’s smoke or fire risk, leave the property and call 999.
    • Call an emergency electrician (24/7) and tell them: “Lights dim when appliances start” + any smells/heat/tripping.
  4. If there are no danger signs but the dimming is noticeable or happening in multiple rooms:
    • Stop using high-load appliances for now (kettle, microwave, tumble dryer, portable heaters, shower, oven) until you’ve had it checked.
    • Check whether it’s just your home: ask a neighbour (or look outside) to see if nearby homes/street lights seem affected.
    • Contact the electricity network operator to report possible voltage fluctuations:
      • England, Scotland, Wales: call 105 (free, 24/7).
      • Northern Ireland: contact NIE Networks (their emergency/24-7 reporting line), or report online.
  5. If you rent or live in managed housing: Report it to your landlord/agent/building manager immediately as an urgent electrical safety issue. Put it in writing and keep a copy.
  6. Write down 5 facts (takes 1 minute): which appliance(s), which rooms, how often, any trips at the consumer unit, and any smells/heat. This makes the electrician/network report faster and safer.

What can wait

  • You do not need to decide the “cause” right now (overload vs wiring vs supply).
  • You do not need to buy surge protectors, new bulbs, or replacement appliances tonight.
  • You do not need to run diagnostics or take covers off sockets/switches.

Important reassurance

This is a common “something’s not right” warning sign, and taking a cautious approach is sensible. Turning things off and getting the right professional to check is how most serious electrical problems are prevented from becoming emergencies.

Scope note

This covers first steps to reduce immediate risk and get the right help. Any testing, load calculations, or repairs should be done by a qualified electrician or your electricity network operator.

Important note

This is general information, not a substitute for on-site electrical assessment. If you think there’s immediate danger (smoke, fire, sparks, burning smell, or someone is at risk), prioritise getting to safety and calling emergency services.

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