What Is a Miniature Circuit Breaker?


Circuit breakers are electrical switches that are automatically activated to prevent damage to circuits due to short circuits or overload. Miniature circuit breakers carry out this function in specific applications.


  • Miniature circuit breakers cut off a circuit, or provide circuit interruption, when overload conditions are detected in a controlled circuit. Miniature circuit breakers are most commonly used in residential electrical units and in commercial buildings to control power sent from an electrical supply to the protected circuits.


  • Miniature circuit breakers contain two contacts that close and open via a spring-based mechanism. A thermal magnetic trip device in the circuit breaker trips the spring when current levels increase above a certain limit, which in turn causes the breaker contacts to open to divert the current.

Ground Fault Detection

  • Some advanced miniature circuit breaker designs house a fault-detection system. This system enables the breaker contacts to open in the event that a line-to-ground fault, or short circuit, is detected.


  • Photo Credit switch image by Clark Duffy from Fotolia.com
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