What is a device that interrupts the flow of electricity when the current exceeds a certain level?

A circuit breaker is designed to interrupt the flow of electricity automatically when the current flowing through the circuit exceeds a predetermined level. This safety device protects the electrical circuit from overload conditions, which can lead to overheating or even fires. When excessive current is detected, the circuit breaker opens the circuit, breaking the connection and stopping the flow of electricity.

In contrast, a fuse serves a similar purpose but works by melting a metal wire when the current exceeds a safe limit, thus permanently disrupting the circuit until the fuse is replaced. A switch simply allows or stops the flow of electricity at the operator's discretion and does not respond to current levels. A surge protector, on the other hand, is designed to protect devices from voltage spikes rather than controlling the current flow in a circuit.