Caution
A light switch in your home has stopped working: toggling it has no effect and the light stays off.
A light that stays fully on whatever you do at the switch means the switch is no longer breaking the circuit: failed contacts, a stuck smart or dimmer module, or wiring that bypasses it. Turn it off at the lighting circuit breaker and book an electrician. Do not change the bulb with it live.
Low risk
Your dimmer switch has stopped working: it will not dim the lights, or the light flickers, buzzes, or does not come on at all.
Your bathroom or toilet pull cord light switch is not working: you pull and nothing happens, or the cord feels loose and never clicks. In UK homes that usually means a worn ceiling-mounted mechanism, a cord snapped inside the housing, a failed bulb, or a tripped lighting circuit, not a "mystery" fault. Do the safe checks below (bulb, consumer unit, listen for a click). If the cord still will not work, or the ceiling plate is warm, discoloured, or smells of burning, isolate the lighting circuit if safe and book an electrician. Bathroom electrical work must respect zones, IP ratings, and Part P rules where they apply.
An outside light on your property has stopped working: it will not come on from the switch or automatically.
Your motion-sensor (PIR) light is not coming on when it should, stays on permanently, or behaves erratically.
A light in your home is stuck at a low brightness and will not go to full brightness, or it glows faintly even when switched off.
A light controlled by two switches (such as a landing or hallway light) can only be operated from one switch, or neither switch works.
Your smart light switch has stopped responding to app commands, voice control, or physical button presses.
High risk
Your light switch makes a crackling, snapping or zapping sound when you operate it, or randomly while the light is on. That is usually arcing at worn contacts or a loose connection: isolate the lighting circuit if safe and book an electrician before it overheats.
Describe the job and get a fixed price from a local electrician.
