What is the main reason a circuit breaker is used in a household electrical system?

A circuit breaker is primarily designed to prevent circuit overloads. Its main function is to interrupt the flow of electricity when it detects a fault condition, such as an overload or a short circuit, which could lead to excessive heat and potentially start a fire. By tripping and breaking the circuit, it protects both the electrical system and the household from dangerous situations that can arise from too much current flowing through the wires.

The other options do not accurately reflect the purpose of a circuit breaker. For instance, while enhancing power supply and regulating voltage are important aspects of an electrical system, they are typically managed by other components like transformers and voltage regulators. Additionally, a circuit breaker does not convert AC to DC; that function is performed by rectifiers or similar devices designed for that purpose. Therefore, the role of a circuit breaker as a safety measure against circuit overloads is the central reason for its presence in a household electrical system.