Final answer:
The question pertains to electrical safety, specifically the grounding of electrical equipment to prevent shock and thermal hazards. Grounding allows excess electrical charge to safely dissipate into the earth, which is crucial for safety when a person comes into contact with a potentially electrified appliance case. Calculations such as voltage on the case due to body resistance and effects on circuit breakers may be needed for complete analysis.
Step-by-step explanation:
The question refers to grounding electrical equipment in ungrounded systems, which is a critical aspect of electrical safety. Grounding is the process by which a conductor is fixed at zero volts by connecting it to the earth with a good conductor. This connection ensures that any excess electrical charge can safely dissipate into the earth rather than building up and posing a risk. In the scenario described, where a short circuit to the grounded metal case of an appliance occurs, a person who comes into contact with this case can become part of the electrical path. If the person is wet and has a resistance of just 3.00 kΩ to earth, this can have serious consequences for their safety.
Addressing the integrated concepts mentioned, let's calculate the potential hazards:
- (a) The voltage on the case can be found using Ohm's law (V = I x R). For a current (I) of 5.00 mA through a resistance (R) of 3.00 kΩ, the voltage (V) on the case would be 15 volts.
- (b) To find the current in the short circuit given the resistance of the earth/ground wire at 0.200 Ω, we would apply Ohm's law again. However, additional information such as the voltage source is needed to accurately calculate this.
- (c) Whether or not the 20.0 A circuit breaker will be triggered depends on the total current flowing through the circuit including the short circuit and any loads connected to it.
Circuit breakers and fuses are systems in place to interrupt excessive current and protect against thermal hazards, while the three-wire system also helps in mitigating both thermal and shock hazards by using live/hot, neutral, and ground wires. Proper grounding of the neutral wire and the appliance's case is essential to ensure safety and prevent hazardous situations.