What is the primary function of circuit breakers?

The primary function of circuit breakers is to protect the wire from an electrical overload. Circuit breakers are designed to automatically interrupt the flow of electricity in a circuit when they detect an overload or a short circuit condition. This is crucial because excessive current can lead to overheating and potentially cause electrical fires. By tripping and cutting off the power, circuit breakers help ensure that the wiring in a home or building remains safe, preventing damage and reducing the risk of hazards.

In the context of other choices, limiting shock duration refers more to ground fault circuit interrupters (GFCIs), which are designed to protect people from electric shock. Regulating power to attached equipment is typically a function of devices like voltage regulators or transformers, while measuring current in a circuit is performed by an ammeter or similar device, not by a circuit breaker itself. Thus, protecting the wire from an overload is the essential and primary role of a circuit breaker.