Final answer:
Electric power causes heating effects due to short circuits and overloading of wires, which can lead to hazards.
Step-by-step explanation:
Electric power causes undesired heating effects whenever electric energy is converted to thermal energy at a rate faster than it can be safely dissipated. One example of this is a short circuit, which occurs when insulation on wires leading to an appliance has worn through, allowing the two wires to come into contact. The resistance of the short is very small, resulting in a large amount of power dissipated in the short and potentially raising the temperature of surrounding materials, melting or igniting them.
Additionally, another thermal hazard occurs when wires supplying power to an appliance are overloaded, meaning that the current exceeds the rated maximum current. This can cause the wires to overheat and potentially lead to fire or other hazards. Fuses and circuit breakers are used to limit excessive currents and prevent such hazards.