NSC NSC Electrical Safety 2 — Questions and Answers
Question 1: At what current level (in milliamps) can electrical shock cause ventricular fibrillation in the human heart?
- 100 mA (Correct answer)
- 10 mA
- 500 mA
- 1 mA
Correct answer: 100 mA
Currents as low as 100 milliamps (0.1 ampere) passing through the chest region can cause ventricular fibrillation and death.
Question 2: What color is the ground wire in a standard US three-prong electrical cord?
- Green or bare copper (Correct answer)
- White or gray
- Black
- Red
Correct answer: Green or bare copper
In US wiring, the ground wire is green or bare copper, the neutral is white, and the hot wire is black.
Question 3: What is the primary purpose of a lockout/tagout (LOTO) procedure related to electrical safety?
- To de-energize electrical equipment and prevent accidental re-energization during maintenance (Correct answer)
- To lock electrical panels so only supervisors can access them
- To tag electrical cords that need replacement
- To comply with arc flash labeling requirements
Correct answer: To de-energize electrical equipment and prevent accidental re-energization during maintenance
LOTO procedures isolate energy sources and lock them out so equipment cannot be accidentally re-energized while workers perform maintenance.
Question 4: Which type of PPE is classified as 'dielectric' and protects workers from electrical shock?
- Rubber insulating gloves rated for the voltage class (Correct answer)
- Hard hat with a chin strap
- Leather work gloves
- Anti-static wrist strap
Correct answer: Rubber insulating gloves rated for the voltage class
Rubber insulating gloves with an appropriate voltage class rating are classified as dielectric PPE and protect against electrical shock.
Question 5: According to NSC guidelines, what should workers do before using portable electric tools?
- Inspect the tool and cord for visible damage, fraying, or missing ground prongs (Correct answer)
- Check the tool's wattage rating only
- Plug in and test briefly before inspection
- Verify the tool is less than five years old
Correct answer: Inspect the tool and cord for visible damage, fraying, or missing ground prongs
Workers must visually inspect portable tools and their cords for damage, fraying, or missing grounding prongs before each use.
Question 6: What does an electrical panel's 'arc flash label' required by NFPA 70E indicate?
- The incident energy level, PPE category, and working distance for safe maintenance (Correct answer)
- The panel's installation date and installer name
- The maximum amperage the panel can carry
- The color code for each circuit breaker
Correct answer: The incident energy level, PPE category, and working distance for safe maintenance
NFPA 70E arc flash labels provide workers with the incident energy, PPE category, and safe working distance for each piece of equipment.
NSC NSC Electrical Safety 2
At what current level (in milliamps) can electrical shock cause ventricular fibrillation in the human heart?