A burning smell from an electrical fitting, socket, switch, consumer unit, or appliance is a sign that electrical components are overheating and should not be ignored. The odour is typically acrid or reminiscent of hot plastic and may begin faintly, becoming more noticeable as the underlying fault develops.
Overheating can result from loose terminal connections that arc at the contact point, cables that are undersized for the load passing through them, moisture that has entered a fitting and compromised the insulation, or age-related deterioration of wiring and components. If you notice a burning smell from any fixed electrical fitting, switch off the circuit at the consumer unit if it is safe to reach, and avoid using the fitting until it has been assessed.
Do not attempt to open a socket or switch plate yourself — internal arcing or live conductors may be present even when the fitting looks undamaged on the outside. If an electrical fitting is smoking or there is a suspected fire, leave the building immediately if your escape route is clear, stay out and call 999 for the fire service.
Do not investigate or try to tackle the fire. If you cannot escape safely, call 999 immediately and follow the control operator's instructions.
An electrician is not a substitute for the emergency response; electrical repairs should be considered only after the emergency has been made safe. An electrician will isolate the circuit and carry out a visual inspection of the fitting, examining terminal connections and the condition of cables at the back of the fitting.
Insulation resistance tests along the affected circuit will confirm whether cable integrity has been compromised in a single location or across a wider section of wiring. Early assessment allows a localised connection fault to be resolved before it causes more extensive damage to the installation.