Final answer:
Grounding is the process of connecting a conductor to the earth to fix it at zero volts, ensuring safety and proper circuit operation. In a three-wire system, grounding involves three connections to earth, and a properly grounded system can prevent electric shock and trigger safety mechanisms like circuit breakers.
Step-by-step explanation:
Understanding Equipment Grounding Conductor Connections
The connection between two or more portions of the equipment grounding conductor is crucial for electrical safety and proper circuit operation. The process by which a conductor is fixed at zero volts by connecting it to the earth with a good conductor is known as grounding. Grounding provides a low-resistance path directly to the earth, ensuring that the neutral wire remains at zero volts relative to the earth, which makes it safe to touch even without insulation.
Furthermore, in a three-wire system, grounding supplies an alternative path for electric current to complete the circuit, in case of a fault. This system usually includes three connections to ground: one near the power source, typically at the generating plant, another at the user's location, and the third connection is to the case of the appliance via a green ground wire. This ensures that the case is also at zero volts and safe to touch, preventing electric shock. An example of proper grounding is shown when a three-prong plug connects appliances to the three-wire system, providing a clear path to ground and safety mechanisms such as the activation of a circuit breaker in case of a fault.
When the insulation of a live/hot wire is compromised, direct contact with an appliance's metal case can lead to electric shock. However, with a proper ground connection, a circuit breaker will trip, indicating the need for appliance repair and preventing potential hazards. Figure 10.45 illustrates scenarios of both a broken ground leading to electric shock and a functional grounding system that triggers a circuit breaker for safety.