E2 Safety Standards and Practices 2 — Questions and Answers
Question 1: What is the minimum approach distance for qualified workers near energized 480V conductors without PPE barriers?
- Restricted approach boundary (Correct answer)
- Limited approach boundary
- Prohibited approach boundary
- Arc flash boundary
Correct answer: Restricted approach boundary
The restricted approach boundary defines the closest distance a qualified worker may approach energized conductors without additional protection measures.
Question 2: Under OSHA 29 CFR 1910.333, de-energized electrical equipment must be locked out before work begins unless the employer can demonstrate that de-energizing would:
- Cause a greater hazard or is infeasible due to equipment design (Correct answer)
- Save less than 30 minutes of downtime
- Require more than two workers to accomplish
- Require special tools not on site
Correct answer: Cause a greater hazard or is infeasible due to equipment design
OSHA allows energized work only when de-energizing creates a greater hazard or is infeasible due to equipment design or operational limitations.
Question 3: Which NFPA 70E hazard/risk category requires an arc flash suit with a minimum arc rating of 40 cal/cm²?
- Category 3
- Category 1
- Category 2
- Category 4 (Correct answer)
Correct answer: Category 4
NFPA 70E Category 4 (now referred to in the PPE table) requires a minimum arc rating of 40 cal/cm² for protection against higher-energy arc flash incidents.
Question 4: When inspecting a commercial switchboard, an inspector notices an arc flash label that is over 5 years old. According to NFPA 70E, this label should be:
- Updated through a new arc flash hazard analysis (Correct answer)
- Replaced with a generic 4 cal/cm² label
- Covered with a warning sticker only
- Left in place if no equipment changes occurred
Correct answer: Updated through a new arc flash hazard analysis
NFPA 70E requires arc flash hazard analyses to be reviewed at intervals not to exceed 5 years, necessitating an updated label.
Question 5: A commercial building's electrical panel room has a working space depth of 2.5 feet in front of a 480V switchboard. According to NEC 110.26, this is:
- A violation; minimum depth is 3 feet for voltages 151–600V (Correct answer)
- Compliant for any voltage up to 600V
- Compliant only if rear access is available
- A violation; minimum depth is 4 feet for voltages above 240V
Correct answer: A violation; minimum depth is 3 feet for voltages 151–600V
NEC 110.26(A)(1) requires a minimum working space depth of 3 feet for systems 151–600V (Condition 1).
Question 6: An E2 inspector observes that a 277V fluorescent lighting circuit has no GFCI protection in a commercial kitchen wet location. Which code section applies?
- NEC 210.8(B) requires GFCI for 277V circuits in commercial wet locations (Correct answer)
- NEC 210.8(B) only covers 120V receptacles in commercial kitchens
- NEC 215.9 mandates AFCI for all lighting circuits
- NEC 230.95 requires GFPE for services over 150V
Correct answer: NEC 210.8(B) requires GFCI for 277V circuits in commercial wet locations
NEC 210.8(B) requires GFCI protection for personnel in commercial kitchens, including 277V circuits used in wet locations.
Question 7: During a commercial inspection, an inspector finds that a contractor used aluminum conductors for branch circuits in a multi-family dwelling. What is the primary safety concern?
- Aluminum can cause loose connections leading to overheating at terminals rated for copper only (Correct answer)
- Aluminum has lower resistance than copper causing nuisance tripping
- Aluminum conductors are prohibited for any use above 120V
- Aluminum is only prohibited in wet locations
Correct answer: Aluminum can cause loose connections leading to overheating at terminals rated for copper only
Aluminum conductors connected to terminals rated only for copper (CU) can loosen over time due to thermal expansion differences, creating a fire hazard.
E2 Safety Standards and Practices 2
What is the minimum approach distance for qualified workers near energized 480V conductors without PPE barriers?