Modern 240V appliances typically have a neutral connection for several reasons related to safety and functionality. Let's explore them in detail:
Safety and electrical code compliance: In many countries, electrical codes require appliances to be designed with a neutral connection for safety purposes. The neutral wire provides a return path for current in normal operation, allowing for a balanced flow of electricity. This helps prevent potential hazards like electric shock and electrical fires.
Compatibility with 120V loads: While 240V appliances primarily operate using two hot wires (line and phase), many appliances also include components that require 120V power. By including a neutral connection, these appliances can accommodate both 240V and 120V loads, allowing for greater versatility.
Ground fault protection: The option to bond the neutral to ground in three-wire installations serves as a safety measure known as "ground fault protection." In such installations, a ground fault circuit interrupter (GFCI) is typically used to monitor the flow of current between the hot wires and the neutral wire. If an imbalance is detected, indicating a ground fault (e.g., current flowing through unintended paths, like a person), the GFCI quickly interrupts the circuit, preventing potential injury or damage.
Regarding your concern about passing current through the ground wire, it's important to note that under normal conditions, the ground wire should not carry any current. The ground wire is primarily intended to provide a safe path for electrical faults, such as a short circuit or ground fault, allowing excess current to flow to the ground and trip the circuit breaker or blow a fuse. It acts as a backup safety measure and should not be relied upon to carry normal operating currents.
However, it's crucial to follow the electrical codes and consult with a qualified electrician when installing or modifying electrical systems to ensure compliance and safety. Electrical requirements can vary depending on your location, so local regulations should always be considered.