Circuit breakers are over-current protective devices that are responsive to electric current and to temperature. These circuit breakers are either externally mounted in their own enclosures or internally mounted in switches or other control devices.
- TYPE I [AUTOMATIC RESET]: Cycle or continuously reset until overload is corrected. These devices are sometimes called "cycling breakers."
- TYPE II [MODIFIED RESET]: Remain open as long as the overload exists, and reset when the overload gets corrected. Power must be disconnected for breaker to reset. These devices are sometimes called "non-cycling breakers."
- TYPE III [MANUAL RESET]: Remain open until manually reset by pushing the button.
Type I, Type II, and Type III circuit breakers, conform to SAE recommended practice J 553C.