ASP Electrical Safety 5

Question 1

What is 'step potential' and why is it hazardous near a downed power line?

Accepted Answer

The voltage difference between two points on the ground surface that can drive current through a person's legs and body

Answer

Step potential is the voltage gradient across the ground near a fault or downed conductor; a person standing with feet at different distances from the source completes a circuit through their legs.

Question 2

What does the term 'flash protection boundary' mean in NFPA 70E arc flash analysis?

Accepted Answer

The distance beyond which arc flash PPE is no longer required because incident energy is below 1.2 cal/cm²

Answer

The flash protection boundary is the distance at which incident energy equals 1.2 cal/cm², the threshold for a second-degree burn, and marks where arc flash PPE is required.

Question 3

Which class of fire extinguisher is appropriate for energized electrical equipment fires?

Accepted Answer

Class C

Answer

Class C extinguishers use non-conductive agents (such as CO₂ or dry chemical) suitable for fires involving energized electrical equipment.

Question 4

An arc flash hazard analysis identifies an incident energy level of 25 cal/cm² at the worker's position. What arc flash PPE category (per NFPA 70E) is required at minimum?

Accepted Answer

Category 3 (25 cal/cm² min rating)

Answer

NFPA 70E PPE Category 3 covers incident energies up to 25 cal/cm²; the worker's PPE must be rated at or above the calculated incident energy.

Question 5

What distinguishes a 'qualified person' from an 'unqualified person' under OSHA electrical standards?

Accepted Answer

A qualified person has been trained and demonstrated skills and knowledge related to electrical equipment construction and hazards

Answer

OSHA defines a qualified person as one who has received training in and demonstrated skills and knowledge of electrical equipment, including hazard recognition and safe work practices.

(ASP) Associate Safety Professional Practice Test

(ASP) Associate Safety Professional Practice Test

ASP Electrical Safety 5