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An earthing system (UK and IEC) or grounding system (US) connects specific parts of an electric power system with the ground, typically the equipment's conductive surface, for safety and functional purposes. [1] The choice of earthing system can affect the safety and electromagnetic compatibility of the installation.
The primary reason for the use of isolated grounds (IG) is to provide a noise-free ground return, separate from the equipment grounding (EG) return. The EG circuit includes all of the metal conduit, outlet boxes, and metal enclosures that contain the wiring and must be grounded to provide a safe return path in case of fault currents.
A shorting bar connecting ground and neutral in Swiss industrial building (outlined in red). A hunk of copper is visible that is designed to be easily connected or disconnected from its place between two screws, rated for 600 A (as stamped on it).
Most circuits have the metallic components interconnected with a grounding wire connected to the third, round prong of a plug, and to metal boxes and appliance chassis. Furnaces , electric water heaters , heat pumps , central air conditioning units, electric dryers , electric stoves or cooktops , and built-in microwave ovens must be on ...
A ground fault protection relay must trip the breaker to protect the circuit before overheating of the resistor occurs. High-resistance grounding (HRG) systems use an NGR to limit the fault current to 25 A or less. They have a continuous rating, and are designed to operate with a single-ground fault.
Such devices may be found in the form of either a circuit breaker, known as an earth-leakage circuit breaker (ELCB), or built into a socket (aka receptacle). Voltage-operated ELCBs can still be found in the wild, though these largely fell out of favour after the invention of the current-sensing based RCD (aka GFCI) technology.
The ground tab is designed to be attached to the outlet faceplate screw, which is supposed to be connected to the building electrical ground. A cheater plug, AC ground lifter or three-prong/two-prong adapter is an adapter that allows a NEMA 5-15P grounding-type plug (three prongs) to connect to a NEMA 1-15R non-grounding receptacle (two slots).
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.