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Breakers for protections against earth faults too small to trip an over-current device: Residual-current device (RCD), or residual-current circuit breaker (RCCB) — detects current imbalance, but does not provide over-current protection. In the United States and Canada, these are called ground fault circuit interrupters (GFCI).
A residual-current device (RCD), residual-current circuit breaker (RCCB) or ground fault circuit interrupter (GFCI) [a] is an electrical safety device that interrupts an electrical circuit when the current passing through a conductor is not equal and opposite in both directions, therefore indicating leakage current to ground or current flowing to another powered conductor.
A ground conductor only carries significant current if there is a circuit fault that would otherwise energize exposed conductive parts and present a shock hazard. In that case, circuit protection devices may detect a fault to a grounded metal enclosure and automatically de-energize the circuit, or may provide a warning of a ground fault.
Incorrectly configured or old model reclosers have been implicated in the starting or spread of wildfires. Research into the Australian 2009 Black Saturday Bushfires indicated that reclosers operating as single shot circuit breakers with Sensitive Ground Fault protection configured at 500mA would reduce fire start risk by 80%.
When a fault occurs, a small current will flow to the ground also. This makes an imbalance between line and neutral current creating an unbalanced magnetic field. This induces a current through the secondary winding, which is connected to the sensing circuit. This will sense the leakage and send signal to tripping system.
A distribution board (also known as panelboard, circuit breaker panel, breaker panel, electric panel, fuse box or DB box) is a component of an electricity supply system that divides an electrical power feed into subsidiary circuits while providing a protective fuse or circuit breaker for each circuit in a common enclosure.
Hot is any line or neutral conductor (wire or otherwise) connected with an electrical system that has electric potential relative to electrical ground or line to neutral. Ground is a safety conductor with a low impedance path to earth. It is often called the "ground wire," or safety ground. It is either bare or has green insulation. [1]
In transmission line faults, roughly 5% - 10% are asymmetric line-to-line faults. [2] line-to-ground fault - a short circuit between one line and ground, very often caused by physical contact, for example due to lightning or other storm damage. In transmission line faults, roughly 65% - 70% are asymmetric line-to-ground faults. [2]