If an electrical junction box heats up, the cause may be a loose terminal, overload, oxidation, weak wire connection or incorrect installation. This is risky because the fault can stay hidden behind a wall or ceiling.
Burning smell, darkened cover, flickering lights, intermittent sockets, crackling sounds or breaker trips mean the circuit should be checked quickly.
An electrician disconnects the circuit, verifies voltage, opens the box, checks terminals, insulation and load, then rebuilds damaged connections safely.