Final answer:
Most overload devices operate when there's a build-up of heat, which can cause a resistor to change state. Fuses and circuit breakers are used to limit excessive currents.
Step-by-step explanation:
Most overload devices operate when there's a build-up of heat. If an excessive amount of current flows through a resistor, the resistor will heat up so much that it can change state, violating Ohm's law. When this happens, overload devices such as fuses and circuit breakers are used to automatically open the circuit and limit the excessive current.