Final answer:
The most effective method for protecting against electrical current damage is service and equipment grounding, as it prevents thermal and shock hazards. Circuit breakers and GFCIs also contribute to safety by interrupting excessive currents and detecting current leaks, respectively.
Step-by-step explanation:
Among the methods listed for protecting machines, tools, and operators against damage from electrical current, service and equipment grounding is the most effective. Grounding helps to prevent both thermal and shock hazards. The three-wire system, which includes live/hot, neutral, and earth/ground wires, ensures that the neutral wire and case of the appliance are grounded. A significant function of the grounding system is to provide a safe path for the dissipation of fault currents, electrical surges, and static discharges.
Circuit breakers and fuses protect against thermal hazards by interrupting excessive current flow. They are designed to trip and open the circuit when current exceeds a certain threshold, preventing overheating and potential fires. Circuit breakers react quickly and can be reset after tripping, which also makes maintenance simpler.
Ground fault circuit interrupters (GFCIs) offer added protection by detecting differences in current that may indicate a leakage to unintended paths, which could result in electric shocks. They are especially useful in wet areas of a home, such as bathrooms and kitchens, where the risk of shock is higher.
While insulation, surge protection devices, and circuit breakers are vital safety components, grounding is fundamental to a comprehensive safety system and thus is the most effective overall.