OHST Practice Exam

In which situation could a double-insulated, two-wire portable drill create a shock hazard?

1. All cases, it requires a third ground wire

2. Short between white and black wire

3. Short between case and black wire

4. If the energized drill was dropped in water

The correct answer is: If the energized drill was dropped in water

A double-insulated, two-wire portable drill is designed to reduce the risk of electric shock by providing two layers of insulation between the electrical components and the user. This design typically eliminates the need for a ground wire. In the situation where the energized drill is dropped in water, the water can provide a conductive path that allows electricity to move from the drill into the water. If the drill's insulation fails or if there is a fault within the tool that causes live parts to contact the exterior casing, the case can become energized. If someone comes in contact with the energized casing while standing in water, this creates a significant shock hazard. The combination of the conductive water and the energized drill increases the risk of electric shock to anyone nearby. Other scenarios, while theoretically possible, do not necessarily result in an immediate shock hazard as described in the correct answer. For example, a short between wires may not independently create a shock hazard if proper insulation is maintained, while the requirement of a third ground wire does not apply to double-insulated tools unless additional external factors introduce risks.