Ground and neutral
In electrical engineering, ground (or earth) and neutral are circuit conductors used in alternating current (AC) electrical systems. The neutral conductor carries alternating current (in tandem with one or more phase line conductors) during normal operation of the circuit. By contrast, a ground conductor is not intended to carry current for normal operation, but instead connects exposed conductive parts (such as equipment enclosures or conduits enclosing wiring) to Earth (the ground), and only carries significant current in the event of a circuit fault that would otherwise energize exposed conductive parts and present a shock hazard. In such case the intention is for the fault current to be large enough to trigger a circuit protective device that will either de-energize the circuit, or provide a warning. To limit the effects of leakage current from higher-voltage systems, the neutral conductor is often connected to earth ground at the point of supply.
Significant voltage unintentionally appearing on exposed conductive parts of an electrical installation can present danger, so the installation of ground and neutral conductors is carefully regulated in electrical safety standards. Under certain strict conditions the same conductor may be used for providing both ground and neutral functions together.