Final answer:
Class C fires are electrical fires caused by issues such as short circuits, and safety systems like circuit breakers, fuses, and three-wire systems are used to prevent thermal and shock hazards.
Step-by-step explanation:
Electrical Safety: Class C Fires and Preventive Devices:
Class C fires refer specifically to electrical fires, which are a result of electrical mishaps, such as short circuits or overloaded electrical wires. These are encountered in a context where the hazard is of an electrical nature and can't be extinguished with water since it can conduct electricity and further the hazard. Safety systems and devices are crucial in preventing these electrical fires and shock hazards associated with electrical systems.
Preventing Thermal and Shock Hazards:
To avert thermal hazards like those causing electrical fires, devices like circuit breakers and fuses are designed to interrupt excessive current flow through the circuit. A three-wire system is another protective measure used to ensure safety against both thermal and shock hazards, which consist of live/hot, neutral, and earth/ground wires with the neutral wire and the case of the appliance grounded.
Overloading wires with electricity beyond their capacity can lead to fires due to excessive heat generation. Thermally, if either current (I) or wire resistance (Rw) is too high, the wires may overheat, leading to thermal hazards. Circuit breakers and fuses protect against these dangers by limiting the current that can flow through an electrical circuit.
As for shock hazards, they occur when electric current passes through the body, potentially causing harm or even fatality. Protective measures such as grounding and proper insulation are essential to prevent such hazards.