OSHA 10-Hour Construction ReviewTools - Hand and PowerEasy
An electrician is using a portable electric drill on a construction site. To protect against electric shock, which of the following is the most effective safety practice?
- AKeeping a fire extinguisher readily available near the work area.
- BEnsuring the drill has a double-insulated mark or is properly grounded.
- CWearing rubber-soled boots while operating the drill.
- DOperating the drill only when the area is dry and free of moisture.
Show answer & explanationAnswer & explanation
Correct answer: B. Ensuring the drill has a double-insulated mark or is properly grounded.
OSHA requires portable electric tools to be either double-insulated or grounded, providing the primary protection against electric shock. This design feature or connection directly prevents current from passing through the user in case of an internal fault.
Why the other options are wrong
- A. A fire extinguisher is for fire hazards, not directly for preventing electric shock during tool operation.
- C. While rubber-soled boots offer some insulation, they are secondary protection and not the primary method required for tool safety.
- D. Avoiding moisture is good practice, but the tool itself must have inherent shock protection, as dry conditions cannot always be guaranteed.
Portable Electric Tool Protection
Portable electric tools must be protected against electric shock through either double insulation or a functional grounding system.
- Look for the 'double-insulated' mark (square within a square).
- If not double-insulated, the tool must have a three-prong plug and be connected to a grounded outlet.
- Never remove the grounding prong from a plug.
Memory trick: Double up on insulation or ground it down!