Final answer:
Power tools not marked as double insulated should have a three-prong plug to ensure safety through grounding, as the third prong is essential for preventing electrical shock, especially in wet conditions. A. have a two-prong plug.
Step-by-step explanation:
Any power tool not marked as double insulated should have a three-prong plug. This is to ensure a proper function of the three-wire system, which includes live/hot, neutral, and ground wires to guard against electrical shock hazards. Tools without double insulation require grounding, and the third prong in a plug provides a low-resistance path to earth/ground. The earth/ground wire is crucial for safety, as it helps to maintain the case of the appliance at zero volts, minimizing the risk of electric shock. This is particularly important in environments where good grounding can contribute to safety, such as in the presence of water.
In the event of a fault, such as worn insulation on the live/hot wire, a tool without proper grounding might not cause a circuit breaker to trip, posing a severe electic shock risk. Therefore, if a power tool is not double insulated and lacks the third prong, severe shock is possible, especially in a wet environment. Consequently, double insulation or a three-prong plug is essential for electrical safety.