ESC Arc Flash & PPE Selection Flashcards
6 cards from real ESC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 ESC Arc Flash & PPE Selection flashcards as text
What causes an arc flash event?
Answer: An electrical arc traveling through ionized air between conductors or to ground
An arc flash occurs when an electrical arc travels through ionized air between conductors or from a conductor to ground, releasing tremendous thermal and blast energy.
Which NFPA standard provides the requirements for arc flash hazard analysis and electrical safety in the workplace?
Answer: NFPA 70E
NFPA 70E, Standard for Electrical Safety in the Workplace, establishes the requirements for arc flash hazard analysis and safe work practices.
In what units is incident energy from an arc flash measured?
Answer: Calories per square centimeter (cal/cm²)
Incident energy from arc flash is measured in calories per square centimeter (cal/cm²), representing the thermal energy density at a given distance from the arc.
The arc flash boundary is defined as the distance at which incident energy equals:
Answer: 1.2 cal/cm²
The arc flash boundary is the distance from the arc source at which incident energy equals 1.2 cal/cm², representing the onset of a second-degree burn on unprotected skin.
What minimum arc rating is required for PPE Category 1 per NFPA 70E?
Answer: 4 cal/cm²
NFPA 70E Table 130.5(G) specifies that PPE Category 1 requires a minimum arc rating of 4 cal/cm².
What does it mean for clothing to be 'arc-rated'?
Answer: The clothing has been tested and assigned an ATPV or energy breakopen threshold (Ebt) rating
Arc-rated clothing has been tested per ASTM F1506 and assigned an ATPV or Ebt rating indicating the level of arc flash protection provided.