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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.
An earth-leakage circuit breaker (ELCB) is a safety device used in electrical installations with high Earth impedance to prevent shock. It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected.
Since the earth leakage is restricted, leakage protection devices can be set to less than 750 mA. By comparison, in a solidly earthed system, earth fault current can be as much as the available short-circuit current. The neutral earthing resistor is monitored to detect an interrupted ground connection and to shut off power if a fault is detected.
Earth fault protection also requires current transformers and senses an imbalance in a three-phase circuit. Normally the three phase currents are in balance, i.e. roughly equal in magnitude. If one or two phases become connected to earth via a low impedance path, their magnitudes will increase dramatically, as will current imbalance.
How is the difference in the currents calculated. If we have a resistor and some simple electrical circuit the current is maximum in the input (something like 220 volts / 16 ampers) but when it gets to the circuit it is lowered to lets say 1 amper (16 ohms resistance) and on the neutral wire we get a maximum of 1 amper current.
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.
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To meet to these standards, electrical products and installations must pass electrical safety tests. Some types of electrical safety tests include: dielectric withstand test (also called a hipot test) insulation resistance test (IR test) earth continuity test; leakage current test