Nollajohdin

Nollajohdin, also known as the neutral wire or the ground wire in some contexts, is a fundamental component in electrical wiring systems. Its primary function is to provide a return path for electrical current in alternating current (AC) circuits. Unlike the live or hot wire, which carries the electrical potential from the power source, the neutral wire is typically maintained at or near ground potential. This is achieved through a connection to earth at the service entrance of a building or at the power substation.

In a typical household wiring setup, a two-conductor system often uses a live wire and a neutral wire to complete the circuit for appliances and lights. A three-conductor system adds a ground wire, which is a separate safety conductor that is not part of the normal current path but is connected to the metal casing of appliances and to the earth. This ground wire serves as a safety measure, providing a low-resistance path for fault current to flow to the ground in case of a short circuit, thereby preventing electric shock.

The distinction between neutral and ground wires is important for safety and proper system operation. While the neutral wire is intentionally kept at ground potential, the ground wire is a protective measure. In some older wiring systems, the neutral and ground wires might have been combined, but modern electrical codes mandate separate conductors for safety reasons. The correct identification and connection of these wires are crucial for the safe and efficient functioning of any electrical installation.