Final answer:
Overheated cables or evidence of arcing are signs of overloading, which occurs when current exceeds the safe limit for wires, leading to excessive power dissipation and potential hazards. Fuses and circuit breakers serve as protective measures by interrupting circuits before they pose risks. A short circuit, resulting from worn insulation, can cause drastic overheating and ignite materials.
Step-by-step explanation:
When electric power cables are burdened with a current that exceeds their safe limit, a thermal hazard called overloading occurs, leading to potential overheating and arcing. The power dissipated in such a scenario can be calculated using the formula P = I² Rw, where P is power, I is current, and Rw is wire resistance. For instance, if an appliance cord is damaged and its resistance increases to 2.00 ohms instead of the intended 0.100 ohms, and if 10.0 A of current is flowing through, this results in 200 W of dissipated power, which is much higher than is considered safe. Additionally, if regular wires with a resistance of 0.100 ohms are carrying 100 A instead of a few amps, the dissipated power could be as high as 1000 W. Devices like fuses and circuit breakers are crucial as they automatically interrupt the circuit when sustained current goes beyond safety thresholds, preventing hazards like fires or equipment damage.
In the case of a short circuit, where insulation wears off and wires come into contact, the low resistance path thus created can lead to excessive dissipation of thermal power, causing materials to melt or ignite. This underlines the importance of proper electrical wiring and protective devices in safeguarding against overheating and potential fires.