Fuses are typically not used in the neutral wire of electrical circuits due to safety and operational considerations. The primary purpose of a fuse or circuit breaker is to protect against overcurrent conditions that could lead to overheating, fire hazards, or damage to electrical equipment. In a typical single-phase AC electrical system, the live wire (also known as the hot wire or phase wire) carries the current to the load, while the neutral wire provides a return path back to the source. The fuse is placed in the live wire rather than the neutral wire because it is designed to interrupt the circuit when excessive current flows through it. Placing the fuse in the live wire ensures that the circuit is immediately disconnected in case of an overcurrent situation, thereby preventing potential hazards and protecting the electrical system.
The neutral wire itself does not normally require a fuse for protection because it carries the current back to the source and is typically at or near ground potential. Unlike the live wire, which alternates between positive and negative voltages relative to ground, the neutral wire generally remains close to ground potential throughout normal operation. Therefore, the risk of an overcurrent condition causing damage or hazards in the neutral wire is minimal compared to the live wire, where the full voltage potential is present. This is why fuses and circuit breakers are installed in the live wire to provide effective protection against overcurrent situations that could pose safety risks or cause equipment damage.
In electrical installations, fuses and switches are typically installed on the phase (live) wire rather than the neutral wire for several reasons related to safety and operational principles. The phase wire carries the active current from the source to the load, while the neutral wire provides the return path back to the source. By placing switches and fuses on the phase wire, electrical circuits can be effectively controlled and protected against overcurrent conditions. Switches allow users to manually open and close the circuit, controlling the flow of electricity to devices and ensuring safe operation. Fuses or circuit breakers, on the other hand, provide automatic protection by interrupting the circuit if excessive current flows, thereby preventing overheating, fires, and equipment damage.
Installing switches and fuses on the phase wire also ensures that the circuit can be safely disconnected from the power source during maintenance or emergencies. This practice follows electrical safety standards and regulations to minimize the risk of electric shock and ensure reliable operation of electrical systems. By focusing protective devices on the phase wire, electrical installations maintain effective control and safety measures, enhancing overall system reliability and performance while adhering to established electrical codes and guidelines.