OSHA 10-Hour Construction ReviewTools - Hand and PowerEasy
A worker is operating a portable electric drill on a construction site. To protect against electric shock, which of the following protection methods is required by OSHA?
- AUse of a two-prong adapter for all outlets.
- BWearing rubber gloves and boots at all times.
- CDouble insulation or grounding.
- DEnsuring the tool is powered by a 12-volt battery.
Show answer & explanationAnswer & explanation
Correct answer: C. Double insulation or grounding.
OSHA requires that portable electric tools either be equipped with a three-wire cord and be grounded, or be approved as double-insulated. Both methods provide protection against electric shock.
Why the other options are wrong
- A. Using a two-prong adapter removes the grounding path and increases the risk of electric shock.
- B. While PPE like rubber gloves and boots can add protection, they are not a substitute for proper tool grounding or double insulation as the primary method.
- D. While low voltage tools are safer, 12-volt battery power is not a universal requirement for all portable electric drills, and corded tools still need grounding/double insulation.
Portable Electric Tool Shock Protection
Portable electric tools must be protected against electric shock either by having an equipment grounding conductor (three-prong plug) or by being double-insulated, as required by OSHA.
- Grounding provides a path for fault current.
- Double insulation uses two layers of insulating material.
- Both methods prevent electric shock.
Memory trick: Ground or double, no shock trouble.