Re: Circuit Breaker Switching


The following types are described in separate articles.

  • Breakers for protections against earth faults too small to trip an over-current device:

    • Residual-current device (RCD, formerly known as a residual current circuit breaker) — Current imbalance, but does not provide over-current protection.
    • Residual current breaker with over-current protection (RCBO) — Combines functions of an RCD and an MCB in one package. In the panel-mounted devices that combine ground (earth) fault detection and over-current protection are called Ground Fault Interrupter (GFI) breakers; a wall mounted outlet device or separately enclosed plug-in device providing ground fault detection and interruption only (no overload protection) is called a Ground Fault Circuit Interrupter (GFCI).
    • Earth leakage circuit breaker (ELCB)—This detects earth current directly rather than detecting imbalance. They are no longer seen in new installations for various reasons.

  • Autorecloser—A type of circuit breaker that closes automatically after a delay. These are used on overhead power distribution systems, to prevent short duration faults from causing sustained outages.
  • Polyswitch (polyfuse)—A small device commonly described as an automatically resetting fuse rather than a circuit breaker.