Final answer:
A short-circuit occurs in a circuit if a live and grounded conductor comes in contact with another live conductor.
Step-by-step explanation:
A short-circuit occurs in a circuit if a live and grounded conductor comes in contact with another live conductor. When this happens, it creates a low-resistance path between the two conductors, resulting in a rapid flow of current. This can lead to overheating, melting, or burning of the wires or components in the circuit.