Final answer:
Grounding connects a conductor to the earth with a good conductor to fix it at zero volts, aiding electrical safety. In the event of a short circuit, grounding provides a safe path for current and helps prevent electric shocks. Circuit breakers protect against excessive current from short circuits.
Step-by-step explanation:
Grounding in electrical systems is the process of connecting a conductor to the earth with a good conductor to fix it at zero volts, thereby ensuring safety in case of faults. When a short circuit to the grounded metal case of an appliance occurs, such as illustrated in Figure 23.57, if someone touches the case while wet, the person's body provides a resistance to the earth/ground. Given that the individual has only a 3.00 kΩ resistance and there is a current of 5.00 mA flowing through them, we can calculate the voltage on the case using Ohm's law (V = IR).
Grounding is essential because it ensures that the neutral wire is at zero volts relative to the earth/ground, making it safe to touch, and provides an alternative path for electricity to complete the circuit. The three connections to earth/ground in a standard three-wire system include the neutral wire, the case of the appliance through the green earth/ground wire, and possibly an earth/ground at the generating plant and the user's location.
To protect against thermal overload, circuit breakers or fuses are included in series on the live/hot wire. If there is a short circuit and the resistance of the earth/ground wire is 0.200 Ω, we can calculate the current in the short circuit. If the flow is greater than the rating of the circuit breaker, in this case, 20.0 A, it would trigger and cut off the electricity supply to prevent damage or fire.