Ground and neutral

As the neutral point of an electrical supply system is often connected to earth ground, ground and neutral are closely related. Under certain conditions, a conductor used to connect to a system neutral is also used for grounding (earthing) of equipment and structures. Current carried on a grounding conductor can result in objectionable or dangerous voltages appearing on equipment enclosures, so the installation of grounding conductors and neutral conductors is carefully defined in electrical regulations. Where a neutral conductor is used also to connect equipment enclosures to earth, care must be taken that the neutral conductor never rises to a high voltage with respect to local ground.

Ground or earth in a mains (AC power) electrical wiring system is a conductor that provides a low-impedance path to the earth to prevent hazardous voltages from appearing on equipment (high voltage spikes). (The terms "ground" and "earth" are used synonymously here. "Ground" is more common in North American English, and "earth" is more common in British English.) Under normal conditions, a grounding conductor does not carry current. Grounding is an integral path for home wiring also because it causes circuit breakers to trip more quickly (ie, GFI), which is safer. Adding new grounds requires a qualified electrician with information particular to a power company distribution region.

Neutral is a circuit conductor that normally carries current back to the source. Neutral is usually connected to ground (earth) at the main electrical panel, street drop, or meter, and also at the final step-down transformer of the supply. That is for simple single panel installations, for multiple panels the situation is more complex.

In the electrical trade, the conductor of a 2-wire circuit connected to the supply neutral point and earth ground is referred to as the "neutral".

In a polyphase (usually three-phase) AC system, the neutral conductor is intended to have similar voltages to each of the other circuit conductors, but may carry very little current if the phases are balanced.

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