A burnt smell from an outlet can mean overheating from a loose connection, worn contacts, overload, or internal damage. Do not keep using it to see whether the smell goes away.
Unplug the load if it is safe to do so
If the receptacle or plug is hot, sparking, or visibly damaged, minimize handling. Turn off the circuit from a safe location if you know which breaker controls it.
Inspect the plug and appliance too
Heat marks concentrated on one plug can point to the cord or appliance, but the receptacle may also have weak contact tension. Keep both out of service until inspected.
Do not test a scorched outlet with another appliance
The absence of flame does not mean it is safe. Carbonization and loose connections can continue generating heat inside the box.
Smoke or fire requires emergency action
If there is smoke, fire, or rapidly increasing wall heat, move away and use emergency services. Receptacle and wiring repair should be performed with the circuit verified de-energized.
Sources
- U.S. Consumer Product Safety Commission — Electrical Safety — Household electrical hazards, receptacles, wiring, breakers, and safe response.