Neutralijohdin

Neutralijohdin, or neutral conductor, is the conductor that completes the electrical circuit by carrying current back to the source in alternating-current power systems. It is connected to the neutral point of the transformer or generator and provides a return path for current, as well as a reference voltage near earth potential in normal operation.

In single-phase systems the neutral carries the current opposite to the live conductor. In three-phase systems the neutral carries the unbalanced portion of the currents from the three phases and may carry little or no current when the loads are perfectly balanced.

The neutral is typically insulated and made of copper or aluminum. In many electrical codes its color is blue (in the EU) or black/white in older installations, and it is intended to be separated from exposed metal parts and from the live conductors.

Safety and grounding: The neutral point is usually bonded to earth at the building inlet to establish a stable reference voltage, but the neutral itself is not a protective earth. Protective devices monitor current in live and neutral to detect leakage and protect against shock and fire. Improper bonding or damage to the neutral can create hazardous situations, including shock risk or equipment malfunction.

Maintenance and cautions: Work on neutral conductors should be performed by qualified electricians with the circuit de-energized; damaged insulation or loose connections can cause shock, fire, or equipment failure. Standards and installation practices vary by country.