If you notice that the body or prongs of a power cord plug are heating up while using an electrical appliance, the following are common real-world causes. The most frequent cause is poor contact between the plug and the socket—for example, worn or loose socket contacts, oxidized or deformed plug prongs, which increase contact resistance and produce noticeable Joule heating as current flows. Another cause is loose crimping of the internal wire connections inside the plug, often seen in cheap rewireable plugs or devices subjected to prolonged vibration. Additionally, if the appliance’s power exceeds the plug’s rated capacity, overheating can occur—for instance, using a 10A plug to continuously carry a 15A current.

Mild warmth (slightly warm to the touch) is normal, but if the plug becomes hot enough to burn your hand (exceeding 60°C), it indicates a hazard. Solutions: First, disconnect power, then check if the socket grips the prongs firmly; clean any oxidation off the prongs; ensure the appliance power matches the plug’s rated current; if the plug housing is deformed or discolored, replace it immediately. Never cover a hot plug or continue using it, as this may cause a fire.