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. 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 in this section; 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. The United States' National Electrical Code and Canadian electrical code only define neutral as the grounded, not the polyphase common connection. In North American use, the polyphase definition is used in less formal language but not in official specifications. In the United Kingdom the Institution of Engineering and Technology defines a neutral conductor as one connected to the supply system neutral point, which includes both these uses. As per Indian CEAR neutral conductor means that conductor of a multi-wire system, the voltage of which is normally intermediate between the voltages of the other conductors of the system and shall also include return wire of the single phase system. All neutral wires of the same earthed (grounded) electrical system should have the same electrical potential, because they are all connected through the system ground. Neutral conductors are usually insulated for the same voltage as the line conductors, with interesting exceptions. Neutral wires are usually connected at a neutral bus within panelboards or switchboards, and are 'bonded' to earth ground at either the electrical service entrance, or at transformers within the system. For electrical installations with split-phase (three-wire single-phase service), the neutral point of the system is at the center-tap on the secondary side of the service transformer. For larger electrical installations, such as those with polyphase service, the neutral point is usually at the common connection on the secondary side of delta/wye connected transformers. Other arrangements of polyphase transformers may result in no neutral point, and no neutral conductors.