Which of the following is one of the three basic measures to avoid electric shock?

• A. Insulation and grounding only
• B. Isolation, insulation, grounding
• C. Grounding and shielding
• D. Insulation, isolation, bonding

Answer: (B)

Protecting people from electric shock relies on three protective approaches: isolation, insulation, and grounding. Isolation means keeping live parts separated from people and placing barriers or distance between them so contact isn’t possible. Insulation uses non-conductive materials to block current from reaching a person, such as insulated gloves, insulating mats, or coated conductors. Grounding provides a low-resistance path for fault current to the earth, so any fault raises exposed parts to earth potential and triggers protective devices to shut the system down.

Among common answer choices, the one that includes all three of these measures—isolation, insulation, and grounding—fits best. Shielding isn’t typically listed as one of the core three measures, and bonding, while related to ensuring a common potential, is not counted in this trio in many safety contexts. Remember these three work together: isolation keeps you away from danger, insulation blocks current, and grounding ensures faults are safely diverted and quickly detected.