Final answer:
Electric circuits are protected from overheating with safety devices such as circuit breakers, fuses, the three-wire system, ground fault interrupters (GFIs), and isolation transformers.
Step-by-step explanation:
Electric circuits are protected from overheating by the use of safety systems and devices such as circuit breakers and fuses. Circuit breakers and fuses interrupt excessive currents to prevent the generation of excessive heat that could lead to thermal hazards. Moreover, the three-wire system which includes live/hot, neutral, and earth/ground wires, contributes to both shock and thermal hazard prevention by ensuring the neutral wire and the appliance's case are grounded.
Another important safety device is the ground fault interrupter (GFI), which prevents shock by detecting current losses to unintentional paths. Additionally, the isolation transformer is used to insulate the device from the original power source to prevent shock. Many of these devices operate using the principle of induction to ensure safety and prevent dangerous overheating.