* Circuit breakers are safety devices designed to automatically interrupt the flow of electricity in a circuit when a fault occurs, such as a short circuit or overload. This prevents excessive current from flowing, which could lead to overheating and potentially a fire.

Let's look at the other options:

* Fuses are another type of safety device that can be used to prevent fires. They work similarly to circuit breakers, but they use a thin wire that melts and breaks the circuit when excessive current flows. However, fuses are not as commonly used in modern households as circuit breakers.

* Earthing is a safety measure that provides a path for electricity to flow safely to the ground in case of a fault. While earthing is essential for safety, it doesn't directly prevent a fire in the case of a short circuit.

* Insulators are materials that resist the flow of electricity. They are used in electrical wiring to prevent current from flowing through unintended paths, but they don't directly interrupt the flow of current in case of a fault.

Therefore, the most effective device used in household wiring to prevent accidental fires caused by short circuits is the circuit breaker.