A Circuit Breaker
A circuit breaker is a safety device to prevent damage to devices in a circuit, such as electric motors, and wiring when the current flowing through the electrical circuit supersedes its design limits. It does this by removing the current from a circuit when an unsafe condition arises. Unlike a switch, a circuit breaker automatically does this and shuts off the power immediately, or darn close to immediately. In this way it works as an automatic service protection device.
A switch is typically used as an isolator, turning power on and off to a particular device. A circuit breaker, on the other hand, can be used to protect a circuit that contains many switches or devices. An exception to this is a disconnect switch, which is used to connect or disconnect power to an entire control panel, or machine.
Simply put, a switch is designed to switch power on and off, a circuit breaker “breaks” the circuit in an overload or fault condition. Switches switch and breakers break. These differences are crucial to understanding their safety and practicality.
The BIG Difference
When it’s all said and done, a big reason NOT to use a circuit breaker as a disconnect switch is a question of endurance. Disconnect switches are designed for a high number of operations, how many times the disconnect switch is turned on and off . Circuit breakers are typically not rated for nearly the same amount of operations.
A miniature circuit breaker is a deceiving simple device. It is a much more complicated device, with more parts, than a switch. Cycling a breaker on and off numerous times will result in its eventual failure.